39 Replies Latest reply: Aug 19, 2015 2:48 AM by HarleyTDavis RSS

    Export HD to NTSC Widescreen -- not truly 16:9

    Sengstack Community Member

      If you export HD footage, 1080x1920 for example, to NTSC Widescreen, you end up with 720x480 with rectangular pixels that have a 1.2121 pixel aspect ratio. That means, the display is effectively 873x480 pixels, which is a a screen aspect ratio of about 16.4:9 instead of 16:9. What you end up with is the original video image squashed between thin, vertical black bars on the right and left sides (not the thick black bars you get when you display a 4:3 video in a 16:9 display).

       

      If you open the video in an NTSC Widescreen Sequence, you'll see those black bars. The video image does not fill the screen.

       

      This is easily fixed: change the Scale Width value to 102.3 (uncheck Uniform Scale). That puts the image portion of the clip into the proper aspect ratio (and shoves the black bars off the left and right sides of the screen). But I'd rather change the scale of all the clips in a project.

       

      Since NTSC has to be 720x480 pixels, if you want to display something at a 16:9 ratio, the pixel aspect ratio should be 1.185 instead of 1.2121.

       

      Perhaps an Adobe engineer can explain why exporting HD to NTSC Widescreen creates a video with black vertical bars and how a 720x480 (with rectangular pixels with a 1.2121 aspect ratio) clip can be considered as having a 16:9 aspect ratio.

       

      Thanks,

       

      Jeff Sengstack

        • 1. Re: Export HD to NTSC Widescreen -- not truly 16:9
          J. Simon Community Member

          Since NTSC has to be 720x480 pixels, if you want to display something at a 16:9 ratio, the pixel aspect ratio should be 1.185 instead of 1.2121.

           

          Dude, I came up with the same answer.  Despite some offered explanations, I find it hard to ignore the math here.  16 divided by 9 = 1.777.  Multiply that by 480 and you get a square pixel "widescreen" resolution of of 853.333.  Divide that by the 720 you're limited to and we end up with the correct PAR of 1.185.

           

          I don't get why that's not recognized.

          • 2. Re: Export HD to NTSC Widescreen -- not truly 16:9
            Bill Engeler Community Member

            Adobe does it the right way. A PAR of 1.185 will give a slightly distorted image in DV widescreen. This was fixed in CS4.  It can be very confusing, but the root of the matter is that a DV frame is not really 4:3 or 16:9 - there is some padding at the sides (18 pixels) that wasn't intended to be part of the visible frame. HD footage doesn't have these extra pixels, so when you go from HD to SD, you see these little pillars on the side. You can change the PAR is you want, but the result is slighly distorted - fatter - than reality. These links can explain it much better than I can:

             

             

            http://www.bbc.co.uk/commissioning/tvbranding/picturesize.shtml

             

            http://help.adobe.com/en_US/AfterEffects/9.0/WS3878526689cb91655866c1103906c6dea-7f3aa.htm l

             

            http://www.lynda.com/home/Player.aspx?lpk4=40550

            • 3. Re: Export HD to NTSC Widescreen -- not truly 16:9
              Ann Bens ACP/MVPs

              These black vertical bars are easily fixed in the export settings.

              On the top left hand side you will find CROP.

              Crop a few pixels of the top and bottom to make it fit.

              For PAL its 13 by 13.

              After cropping you can check it in the output window.

               

              crop on export.png

              • 4. Re: Export HD to NTSC Widescreen -- not truly 16:9
                Powered by Design Community Member

                I really like that Lynda video.

                 

                http://www.lynda.com/home/Player.aspx?lpk4=40550

                 

                They really have some good videos.

                 

                 

                Thanks Bill :  GLenn

                • 5. Re: Export HD to NTSC Widescreen -- not truly 16:9
                  J. Simon Community Member

                  Adobe does it the right way.

                   

                  I'm still not seeing that myself.

                   

                   

                  A PAR of 1.185 will give a slightly distorted image in DV widescreen.

                   

                  According to the math, it provides a prefect, properly sized image. In fact, in order to crop a 16:9 image into a proper 1.85 film aspect*, you need to use the proper math listed earlier.  Using the current PAR, you'll end up cropping too little.

                   

                   

                   

                   

                  *(Another technocrat error, if you ask me, was making HD such a weird aspect ratio.  All they needed was to lose 20 extra pixels (1920 x 1040) to get the proper 1.85:1 aspect ratio of film.)

                  • 6. Re: Export HD to NTSC Widescreen -- not truly 16:9
                    Sengstack Community Member

                    Bill,

                     

                    I checked out the three sites you listed and none explained this issue clearly. They touch on PARs and resolution, but don't explain P Pro's export behavior (two are on After Effects and they don't discuss exporting to other formats). Perhaps you can clarify some points:

                     

                    1) The DV frame. When working in NTSC DV (widescreen or standard definition), the pixels we see in the Program Monitor in P Pro or any NLE are 720x480. The easy way to note that is to look at the Motion effect, Position parameter. The center point is 360/240. So, are you saying that P Pro truncates two 9 pixel wide vertical rectangles from each side when it displays the video in the Program and Source Monitors? Are you saying that the actual DV frame is 738x480?

                     

                    2) HD to NTSC Widescreen export. If P Pro is able to truncate those 9-pixel wide vertical lines to create a clearn display, why doesn't it truncate them when displaying HD footage that has been exported to NTSC Widescreen? Or, conversely, why doesn't P Pro have an option to export HD to NTSC such that the 720x480 image area is all that ends up in the AVI file (and not include the two vertical, 9-pixel wide bars)?

                     

                    3) P Pro displays those 720x480 pixels with a .91 pixel aspect ratio in standard definition and 1.2121 in widescreen. Effectively NTSC SD has a resolution of 655.2 x 480 and NTSC widescreen is 827.7x480. So the SD screen aspect ratio is not 4:3, it is 4.095 to 3. And NTSC widescreen is not truly 16:9, it is 16.36 to 9. Can you clarify that?

                     

                    4) You said you can change the PAR in the export settings. I tried that and it did not work. I used the Uncompressed Microsoft AVI format with Video set to 720x480, Progressive, and with an Aspect of 1.185 to 1 (I chose 1.185 but the display in the Video tab of the Export Settings dialog box shows only whole numbers). The resulting video had a pixel aspect ratio of 1.0 and an data rate of 26.6 MB/sec -- about 7 times the data rate for standard MS AVI. In my NTSC Widescreen Sequence, the clip did not fill the screen and had black bars at the top and bottom. So...How do you export with a PAR of something other than the standard PARs in the Export presets?

                     

                    Thanks,

                     

                    Jeff Sengstack

                    • 7. Re: Export HD to NTSC Widescreen -- not truly 16:9
                      Sengstack Community Member

                      Ann,

                       

                      I do not think cropping leads to the desired result.

                       

                      When you crop in the Export Settings dialog box, you are cropping the image area. So, when you export HD to NTSC Widescreen, you still end up with video that has those two vertical black bars. And if you cropped the left and right sides, that will simply expand the width of the vertical black bars. If you crop only the top and bottom, you still get those vertical black bars plus end up cutting off image area at the top and bottom.

                       

                      The goal is to not have those vertical black bars that P Pro adds to HD footage when exporting to NTSC Widescreen.

                       

                      Jeff

                      • 8. Re: Export HD to NTSC Widescreen -- not truly 16:9
                        Bill Engeler Community Member

                        As I said, it gets confusing, and I'm not an expert - that's why I provided links.  I can perhaps try to answer some of the points you brought up however;

                         

                        1) The DV frame is always 720 x 576 (PAL). It's just not exactly 4;3 or 16;9. 702x576 will give those exact aspect ratios, and is in the same proportion as HD frames. HD reduced to DV will only use 702 pixels across. to not distort the image. 720x 576 is a little wider than 4;3 or 16;9.

                         

                        2) There's no truncating. It's just that HD 1920x1080 is a slightly narrower rectangle than DV widescreen, so it doesn't quite fit right when reduced proportionaly.

                         

                        3) It's Sunday night and I'm on holiday. No math tonight.

                         

                        4) Ann Bens provided an easy way to avoid the bars.  It does distort the image a little, but it's barely noticeable. The other way is to enlarge the image a few percent when transcoding in AME. (I'm not at my editing PC right now, and I forget the details). This might increase rendering time, but I can't say for sure. That doesn't quite answer your last question, I know.

                         

                         

                        • 9. Re: Export HD to NTSC Widescreen -- not truly 16:9
                          Ann Bens ACP/MVPs
                          function(){return A.apply(null,[this].concat($A(arguments)))}

                          Sengstack wrote:

                           

                          Ann,

                           

                          I do not think cropping leads to the desired result.

                           

                          When you crop in the Export Settings dialog box, you are cropping the image area. So, when you export HD to NTSC Widescreen, you still end up with video that has those two vertical black bars. And if you cropped the left and right sides, that will simply expand the width of the vertical black bars. If you crop only the top and bottom, you still get those vertical black bars plus end up cutting off image area at the top and bottom.

                           

                          The goal is to not have those vertical black bars that P Pro adds to HD footage when exporting to NTSC Widescreen.

                           

                          Jeff

                           

                          Just try it, it works. Those few pixels you will hardly miss.

                          • 10. Re: Export HD to NTSC Widescreen -- not truly 16:9
                            Sengstack Community Member

                            Ann,

                             

                            I tried it before sending you my response.

                             

                            If  you trim 25 lines (as you did) then you end up with an image that fits  in the NTSC widescreen 16:9 format. So, I can't disagree with your  approach in terms of avoiding the black, vertical rectangles.

                             

                            On  the other hand, I don't want to slice 2.3% (25 lines / 1080) of my image away. Your  approach, in effect, equals the Motion effect, Scale Width 102.3 (2.3% increase in width) approach I  mentioned in my initial email.

                             

                            Both instances are work-arounds but neither answers the larger question of why those black bars appear in the first place.

                             

                            Jeff

                            • 11. Re: Export HD to NTSC Widescreen -- not truly 16:9
                              Sengstack Community Member

                              Hi Bill,

                               

                              I appreciate that you're maxed out on this. Couple that with the fact that you are the only one who has tried to explain the inner workings of P Pro. So my hat's off to you on that.

                               

                              I'm thinking I'll post this query on a prerelease forum and we'll see if any Adobe engineers weigh in on it.

                               

                              I'll toss out a couple follow-up points in case anyone wants to respond:

                               

                              1) I'm talking only about NTSC here. Perhaps PAL behaves similarly, but I have not examined that format.

                               

                              2) HD 1920x1080 is exactly a 16:9 format.NTSC Widescreen is supposed to be 16:9. So why doesn't P Pro export HD such that it exactly fits into the NTSC 16:9 format. Neither the export cropping work-around described by Ann or the Motion effect Scale Width approach I described should be necessary.

                               

                              3) You talked about NTSC's frame being 18 pixels wider than the image area as a cause of this discrepancy. I think that might be backwards logic. We are exporting from HD to NTSC. If we were going from NTSC to HD, then I suppose those extra 9 pixels per side would have to be dealt with. But that's not the workflow here.

                               

                              Jeff

                              • 12. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                Todd_Kopriva Adobe Employee

                                I'm sorry that I can't get into this thread in depth right now. It's Sunday evening, and I've got three minutes before my wife and I need to leave to meet friends for dinner. But I can at least point to the page that I wrote to deal with these questions for After Effects CS4:

                                http://blogs.adobe.com/toddkopriva/2009/07/pixel-aspect-ratios-in-after-e.html

                                 

                                Premiere Pro CS4 had the same PARs as After Effects CS4, so it seems odd that this is only coming up in the Premiere Pro context now.

                                 

                                The one thing that I'll say before running off is that you have to do your frame aspect ratio calculations based on the image area (clean aperture) not the production aperture. It's the failure to make that distinction that caused all of this confusion in the first place.

                                 

                                Oh, and note that the Foundry and Apple are using the corrected PARs now, too.

                                 

                                If this conversation is still going on tomorrow afternoon (when I emerge from a day of meetings) I'll see if I can help clear up any remaining questions.

                                • 13. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                  Sengstack Community Member

                                  Todd,

                                   

                                  Thanks for checking in on this. I read your blog and visited the links. Most linked articles focused on converting square pixel graphics or image files to non-square pixels. None, that I could see, answered the question that I raised at the outset. So, I'll rephrase it: When I export HD to Microsoft AVI -- NTSC Widescreen, why are there 16 columns of black pixels (eight on a side) in the visible area of the AVI file as I view it in P Pro's Source and Program monitors?

                                   

                                  I think I understand the discussion about clean aperture versus production aperture, such that the actual image information is stored within 704 vertical lines within the 720 vertical lines of the entire frame. But if I look at SD DV AVI files captured straight from the camcorder, P Pro displays color information in all 720 vertical lines visible in the Source and Program monitors. There are no black columns. This despite the explanations stating that the actual image area is 704 vertical lines. So, when P Pro displays DV, does it take those 704 vertical lines and interpolate them into 720?

                                   

                                  Since NTSC Widescreen AVI clips captured straight from a camcorder are also 720x480 pixels, aren't they displayed the same way...with no black bars along the sides?

                                   

                                  So...why is it that when exporting HD to Microsoft AVI -- NTSC Widescreen, P Pro squashes the image area, such that when it plays in P Pro, the video image area in the Program monitor is limited to 704 vertical lines and we see the the remaining 16 black vertical lines. Is P Pro creating a different kind of AVI file than I would get if I shot widescreen DV and captured that as an AVI file?

                                   

                                  I would prefer that P Pro export HD to MS AVI -- NTSC Widescreen and fill all 720 visible vertical lines with color information rather then toss in 16 black vertical columns.

                                   

                                  Jeff

                                  • 14. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                    Bill Engeler Community Member

                                    >>>2) HD 1920x1080 is exactly a 16:9 format.NTSC Widescreen is supposed to be 16:9.

                                     

                                    This is the heart of the matter - NTSC Widescreen (and PAL widescreen) is not 16:9 - it is 16:9 plus a few pixels on the sides.  Thus it is not the same shape as an HD frame. Imagine the slightly skinnier HD frame zooming down into the NTSC (or PAL) widescreen frame. At some point the top and bottom of both frames will exactly align, but the shrunken HD frame, being a little skinnier, will not fill the smaller frame at the sides.

                                     

                                    Now in order to avoid the gap at the sides, you could not shrink the HD frame as much, but this will cause the loss of some of the image at the top and the bottom.  (I wish I could draw a picture right now).  Adobe, and others, have decided that the black pillars at the side are preferable to chopping the image.

                                    • 15. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                      Sengstack Community Member

                                      So, why then do those extra frames on the sides not show up when you capture widescreen DV from a camcorder but show up when you export HD to Microsoft AVI NTSC Widescreen?

                                      • 16. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                        Bill Engeler Community Member

                                        It's because thay are not extra frames - it's just that since the HD frame is not the same shape as the DV frame, it doesn't fill it all the way; it leaves a little on the side when it is reduced.  Since widescreen DV footage is recorded in the camera as 720 x 576 (or whatever for NTSC), there's no reduction, and of course it fills all 720 pixels across.

                                        • 17. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                          tjbonjour Community Member

                                          This thread came up when researching the problem I am attempting to deal with. I have read all the linked articles and have a basic understanding of PAR and the related issues. I am attempting to convert 1920x1880 (PAR 1.0) footage to DV PAL Widescreen and also get the left and right vertical black bars. Of more concern to me is this: I did a test where I carefully superimposed the Safe Margins on the orginal HD footage before the conversion. After the conversion to PAL Widescreen I noticed that the horizontal Safe Margins were perfect, but the vertical (left right) margins had shrunk by about the same width as the black bars, showing that the DV picture was now squished horizontally from the original.

                                          My product is educational and the adherance to correct Safe Margins, particularly Safe Title, is critical. This also means that additional materials (like menus) created for the DV in DVD frame sizes do not line up with converted footage.

                                          • 18. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                            Community Member

                                            I had a project that was shot 16:9 dv ntsc. At some point it was worth my trying to export this project as 16:9 using a 4:3 space...and  FORCE a letterbox type of frame space in the final product. Which did leave black on top and bottom, but didn't distort the video or have black bars on left and right.

                                            To do this I made a new project at 4:3, and put the 16:9 footage in that project and scaled the 16:9 down to fit the frame left and right. ( leaving the black bars on top and bottom). exporting THAT got me what I wanted in the final product for that particular situation.

                                             

                                            Weird, but it worked. Not sure if this clicks with anyone dealing with this problem here, but worth mentioning

                                            • 19. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                              J. Simon Community Member
                                              you have to do your frame aspect ratio calculations based on the image area (clean aperture) not the production aperture.

                                               

                                              That is a question I still have.  Unless I misunderstand those terms, it seems that with digital video, there is no need to distinguish between the two.  With DV, you get the whole image, visible and "clean".  Seems like the distinction is only really necessary for older analog systems.  So why is that applied to digital video where it isn't necessary, and thus provides incorrect aspect?

                                              • 20. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                J. Simon Community Member
                                                NTSC Widescreen (and PAL widescreen) is not 16:9 - it is 16:9 plus a few pixels on the sides.

                                                 

                                                It would seem that may be so only because an incorrect PAR is used.  Were it the proper 1.185, I can't see where extra pixels would be required.  (Well, maybe part of one to get it up to the full 854.)

                                                • 21. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                  Jeff Bellune ACP

                                                  Seems like the distinction is only really necessary for older analog systems.  So why is that applied to digital video where it isn't necessary

                                                  Unless I'm mistaken, it's all about broadcast, broadcast, broadcast per the BBC standard.

                                                   

                                                  -Jeff

                                                  • 22. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                    Colin Brougham Community Member

                                                    Seems like the distinction is only really necessary for older analog systems.  So why is that applied to digital video where it isn't necessary

                                                    Unless I'm mistaken, it's all about broadcast, broadcast, broadcast per the BBC standard.

                                                    Additional to that, remember that digital video recording predates digital broadcasting and digital displays. In other words, digital video (DV) was originally destined for analog broadcasting to analog TV sets; to compensate for that, the whole production vs. clean aperture thing got swirled into the mix.

                                                    • 23. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                      Community Member

                                                      -----------------

                                                       

                                                      you have to do your frame aspect ratio calculations based on the image  area (clean aperture) not the production aperture.

                                                       

                                                      ---------------------

                                                       

                                                      page 4...this link

                                                      http://www.panavision.com/publish/2007/12/10/GenesisFAQs20071207.pdf

                                                       

                                                      -----------

                                                      My take on this is that CCD's that are full size for 35mm film ( beginning of aspect ratios for a lot of stuff ) there is less fudging re: transforming a smaller chip size to the correct exact image size, that the image size derrived from the real camera recording may not be exactly the "production" aspect ratio sizes...or something like that... It is confusing to me also, as I have no video cameras, digital or otherwise, and don't shoot anything but still film.

                                                       

                                                      I think ( not sure but think I read ) that the red camera actually has a CCD "larger" than the genesis, so it actually is capable of recording higher resolutions than typical 4.4.4 production dimensions....but how that works into "clean" image area and aspect ratio is confusing to me also...

                                                       

                                                       

                                                      To further confuse me, this article has info on exact number of lines broadcast for pal and ntsc...

                                                       

                                                      note THIS in the article ===------------------------------------------------------

                                                      NTSC Video

                                                       

                                                      • 525 scan lines per frame,  30      frames per second (or be exact, 29.97 fps, 33.37 msec/frame)
                                                      • Interlaced, each frame is      divided into 2 fields, 262.5 lines/field
                                                      • 20 lines reserved for control      information at the beginning of each field
                                                        • So a maximum of 485       lines of visible data

                                                      ---------------------------------------------------------------------------------------

                                                       

                                                       

                                                       

                                                      Basics of Video

                                                      • Analog video is represented      as a continuous (time varying) signal.
                                                      • Digital video is represented      as a sequence of digital images.
                                                       

                                                          Types of Color Video Signals


                                                      • Component video --      each primary is sent as a separate video signal.
                                                        • The primaries can       either be RGB or a luminance-chrominance transformation of them (e.g.,       YIQ, YUV).
                                                        • Best color       reproduction
                                                        • Requires more       bandwidth and good synchronization of the three components
                                                      • Composite video --      color (chrominance) and luminance signals are mixed into a single carrier      wave. Some interference between the two signals is inevitable.
                                                      • S-Video (Separated      video, e.g., in S-VHS) -- a compromise between component analog video and      the composite video. It uses two lines, one for luminance and another for      composite chrominance signal.

                                                       

                                                          Analog Video


                                                      The following figures are from A.M. Tekalp, "Digital video processing", Prentice Hall PTR, 1995, NTSC.

                                                      NTSC Video

                                                      • 525 scan lines per frame, 30      frames per second (or be exact, 29.97 fps, 33.37 msec/frame)
                                                      • Interlaced, each frame is      divided into 2 fields, 262.5 lines/field
                                                      • 20 lines reserved for control      information at the beginning of each field
                                                        • So a maximum of 485       lines of visible data
                                                        • Laserdisc and S-VHS       have actual resolution of ~420 lines
                                                        • Ordinary TV -- ~320       lines
                                                      • Each line takes 63.5      microseconds to scan. Horizontal retrace takes 10 microseconds (with 5      microseconds horizontal synch pulse embedded), so the active line time is      53.5 microseconds.


                                                      Digital Video Rasters

                                                      • Color representation:
                                                        • NTSC uses YIQ color       model.
                                                        • composite = Y + I cos(Fsc       t) + Q sin(Fsc t), where Fsc is the frequency of color subcarrier

                                                      PAL Video

                                                      • 625 scan lines per frame, 25      frames per second (40 msec/frame)
                                                      • Interlaced, each frame is      divided into 2 fields, 312.5 lines/field
                                                      • Uses YUV color model

                                                       

                                                       

                                                       

                                                          Digital Video


                                                      • Advantages:
                                                        • Direct random access       --> good for nonlinear video editing
                                                        • No problem for       repeated recording
                                                        • No need for blanking       and sync pulse
                                                      • Almost all digital video uses      component video

                                                       

                                                       

                                                      Chroma Subsampling

                                                      • How to decimate for      chrominance?

                                                      • 4:4:4 --> No chroma      subsampling, each pixel has Y, Cr and Cb values.


                                                      4:2:2 --> Horizontally subsample Cr, Cb signals by a factor of 2.

                                                      4:1:1 --> Horizontally subsampled by a factor of 4.

                                                      4:2:0 --> Subsampled in both the horizontal and vertical dimensions by a factor of 2. Theoretically, the chroma pixel is positioned between the rows and columns as shown in the figure.

                                                      • 4:1:1 and 4:2:0 are mostly      used in JPEG and MPEG (see Chapter 4).
                                                       

                                                      CCIR Standards for Digital Video

                                                      (CCIR -- Consultative Committee for International Radio)

                                                                             CCIR 601       CCIR 601         CIF         QCIF
                                                                              525/60         625/50   
                                                                               NTSC         PAL/SECAM       
                                                      --------------------  -----------    -----------   -----------  -----------
                                                       
                                                      Luminance resolution   720 x 485      720 x 576     352 x 288    176 x 144
                                                       
                                                      Chrominance resolut.   360 x 485      360 x 576     176 x 144     88 x 72
                                                       
                                                      Color Subsampling        4:2:2          4:2:2         4:2:0        4:2:0
                                                       
                                                      Fields/sec                60             50            30           30
                                                       
                                                      Interlacing               Yes            Yes           No           No 
                                                       
                                                      • CCIR 601 uses interlaced      scan, so each field only has half as much vertical resolution (e.g., 243      lines in NTSC). The CCIR 601 (NTSC) data rate is ~165 Mbps.
                                                      • CIF (Common Intermediate      Format) -- an acceptable temporary standard
                                                        • Approximately the VHS       quality
                                                        • Uses progressive       (non-interlaced) scan
                                                        • Uses NTSC frame rate,       and half the active lines of PAL signals --> To play on existing TVs,       PAL systems need to do frame rate conversion, and NTSC systems need to do       line-number conversion.
                                                      • QCIF -- Quarter-CIF
                                                       

                                                      ATSC Digital Television Standard

                                                      (ATSC -- Advanced Television Systems Committee) The ATSC Digital Television Standard was recommended to be adopted as the Advanced TV broadcasting standard by the FCC Advisory Committee on Advanced Television Service on November 28, 1995. It covers the standard for HDTV (High Definition TV).

                                                      Video Format

                                                      The video scanning formats supported by the ATSC Digital Television Standard are shown in the following table.

                                                      Vertical Lines

                                                      Horizontal   Pixels

                                                      Aspect Ratio

                                                      Picture Rate

                                                      1080

                                                      1920

                                                      16:9

                                                      60I 30P 24P

                                                      720

                                                      1280

                                                      16:9

                                                      60P 30P 24P

                                                      480

                                                      704

                                                      16:9 &   4:3

                                                      60I 60P 30P   24P

                                                      480

                                                      640

                                                      4:3

                                                      60I 60P 30P   24P

                                                      • The aspect ratio for HDTV is      16:9 as opposed to 4:3 in NTSC, PAL, and SECAM. (A 33% increase in      horizontal dimension.)
                                                      • In the picture rate column,      the "I" means interlaced scan, and the "P" means      progressive (non-interlaced) scan.
                                                      • Both NTSC rates and integer      rates are supported (i.e., 60.00, 59.94, 30.00, 29.97, 24.00, and 23.98).
                                                      • At 1920 x 1080, 60I (which      CBS and NBC have selected), there will be 1920 x 1080 x 30 = 62.2 millions      pixels per second. Considering 4:2:2 chroma subsampling, each pixel needs      16 bits to represent, the bit rate is 62.2 x 16 = 995 Mb/sec.

                                                      Homepage of the Advanced Television Systems Committee (ATSC)

                                                      • 24. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                        Wil Renczes Adobe Employee

                                                        Long thread.  If I can distill it down correctly, the OP question is essentially asking 'why do I get letter boxing?'

                                                         

                                                        Essentially, the problem comes down to the fact that your source doesn't match the destination PAR.  Currently, if the source & destination PARs don't match, you get letter boxing.  Why? From a technical standpoint of 'do no harm', it's bad practice to drop pixels, and the render pipeline is trying to preserve the aspect ratio of your footage.  What you're effectively asking for is a option in AME to 'fit to fill (distort)'.

                                                         

                                                        Currently, as a workaround, if you plan to export to a DV preset, if you nest your HD sequence into a DV sequence, then export the nested version, now your source sequence will match the destination, and that will circumvent the need to letterbox.

                                                         

                                                        Cheers

                                                        • 25. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                          Community Member

                                                          Wil,  which is basically putting the HD into DV and scaling it down to fit the 16:9 DV..correct ?

                                                          • 26. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                            Sengstack Community Member

                                                            With all the back and forth on this, I still don't understand what's going on in P Pro, "under-the-hood," such that when converting from HD to NTSC Widesreen, vertical black bars show up on the left and right edges of the visible area of the AVI clip. No one has yet addressed this transcoding process. If we see 720 columns (I'll use "columns" to avoid confusion with horizontal "lines") of image information in DV whether SD or Widescreen (we don't see any vertical black bars even though they are part of the clip), how come we don't see 720 columns of image information in a clip after converting it from HD to NTSC Widescreen? Why do we see only 704 columns of image information plus two visible, 8-pixel wide, vertical black bars on each side? I follow-up on this question at the end of this note.

                                                             

                                                            But first:

                                                             

                                                            As for displaying DV NTSC SD or Widescreen, I think the following sums up what's been posted here:

                                                             

                                                            DV (SD or Widescreen, NTSC or PAL) has only 704 vertical columns of image area (plus 8 columns off each of the right and left edges that are not supposed to be visible -- 720 columns total).

                                                             

                                                            To display those columns in a standard definition, 4:3 frame aspect ratio, P Pro shrinks the width of the columns by multiplying them by 10/11: 704 * 10/11 = 640). The excess 8 vertical columns on a each side (now slightly narrower as a result of the width reduction) are out of sight and out of mind (even if you scale the clip to less than 100%, P Pro truncates those black bars from the visible area of the clip). So what we see on TV or in our P Pro monitors is an image that is 640 units wide and 480 units tall (a 4:3 frame aspect ratio). P Pro still considers the visible area of the clip as being 720 pixels wide (as evidenced in the Motion effect). And on NTSC or PAL TV sets, it's still 720 pixels wide, because TV set pixels are non-square (and again, the 8 extra vertical columns on the left and right sides are not visible on TVs sets or computer monitors).

                                                             

                                                            When displaying those 704 columns in widescreen (16:9 frame aspect ratio), P Pro expands the width of the columns by multiplying them by 40/33 (1.212.....) as in: 704 * 40/33 = 853.3. So the resulting visible area of the clip is 853.3 units by 480 units (a 16:9 frame aspect ratio). And again, those 8 columns on each side (now a bit wider due to the width expansion) are not visible.


                                                            So, back to the question at the top of this note: Why doesn't P Pro take HD clips, which start their lives in a 16:9 frame aspect ratio, and convert them to NTSC Widescreen such that the resulting clip has 704 columns of visible image information (and 16 non-visible black columns)? In that way, 1920 vertical columns would be interpolated to 704 vertical columns and those columns would be 480 pixels tall. And as part of the conversion process, 8 extra, non-visible vertical columns would be added to each side of the resulting clip.

                                                             

                                                            That, to me, is the crux of this discussion. Since P Pro, other NLEs, video playback software like Media Player, and TV sets all "hide" the two sets of 8 pixel-wide vertical columns (black bars) when displaying NTSC SD or Widescreen, why doesn't P Pro transcode HD to NTSC Widescreen such that those 8 extra lines are not visible in the resulting file?

                                                             

                                                            Jeff

                                                            • 27. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                              J. Simon Community Member

                                                              digital video (DV) was originally destined for analog broadcasting to analog TV sets; to compensate for that, the whole production vs. clean aperture thing got swirled into the mix.

                                                               

                                                              It may have gotten swirled in previous to digital broadcast and displays, but Adobe added it after the fact.  Now that the entire pipeline is digital, that seems as good a time as any to drop some of the old analog ways and develop new standards that are more appropriate to the digital pipeline.

                                                               

                                                              I'm not sure Adobe did the right thing here by conforming DV to old, analog standards.  To wit:

                                                               

                                                              "Although the ATSC A/53 standard limits MPEG-2 transmission to these 18 formats (and their 1000/1001-rate slowed-down versions), the U.S. Federal Communications Commission declined to mandate that television stations obey this part of the ATSC's standard. In theory, television stations in the U.S. are free to choose any resolution, aspect ratio, and frame/field rate, within the limits of Main Profile @ High Level. Many stations do go outside the bounds of the ATSC specification by using other resolutions – for example, 720 × 480."

                                                              • 28. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                                Ann Bens ACP/MVPs

                                                                Actually the black bars is empty space. The background shows as black.

                                                                • 29. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                                  Community Member

                                                                  I guess you're exporting frames and opening in photoshop to measure exactly how many pixels are left and right of frame? which is square pixels..psd...

                                                                  I think the bottom line is that what you see is the result of un-exact measurements...relating to par, dar etc.

                                                                   

                                                                  And a lot of different cameras, who basically translated the japaneese company "standards" of HD ( blue ray etc) according to their not exact language translation...meaning there's a lot of leeway about application of the standard...You would think that translation of science would be more exact but it isn't.

                                                                   

                                                                  If I go from metric to feet and inches, or nautical miles to statute miles, there are discrepancies ...as the math just isnt perfect.  There is some slop in the math, no matter what you do, and the accuracy of math is sometimes in the translation of the different "systems".

                                                                   

                                                                  and this is made more obvious as you translate more than 2 things....like maybe now you are dealing with 3 things..

                                                                   

                                                                  Its a fascinating subject though...thanks for sticking it out and trying to get a definitive answer !

                                                                  • 30. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                                    Sengstack Community Member

                                                                    Perhaps there's one other part of the equation that has not been factored into this conversation:

                                                                     

                                                                    Do P Pro, other NLEs, and software video players treat captured DV AVI files differently than transcoded DV AVI files?

                                                                     

                                                                    What I'm saying is:

                                                                     

                                                                    1) When P Pro or other NLEs capture DV they put the unchanged DV in an AVI wrapper (presumably this applies to MOV wrapped files as well). So, when P Pro, other NLEs, and software video players "see" that captured DV AVI file, they "know" it started it's life as DV captured from a tape, so they do not display the right and left 8-pixel wide columns and use an appropriate pixel aspect ratio value to shrink or expand the width of the remaining 704 columns to display that visible area properly as SD or Widescreen.

                                                                     

                                                                    2) On the other hand, how do P Pro or other NLEs display AVI (and presumably MOV) files that were transcoded rather than captured? I'm reasonably certain that transcoded DV AVI files have image information in all 720 columns. That is, I believe they do not have two black, 8-pixel wide columns on each side that are not supposed to appear in the display. If that's the case, do P Pro, other NLEs, and software video players treat those transcoded DV AVI files differently? That is, do they display all 720 columns?

                                                                     

                                                                    If it is correct to say that there are two types of DV AVI files and P Pro and other software products display them differently, then there are two follow-on comments/questions:

                                                                     

                                                                    1) It appears that when P Pro  (Adobe Media Encoder) exports HD to NTSC DV Widescreen, it "assumes" P Pro will treat that DV AVI file as if it were a captured DV video clip. So it adds 8-pixel wide black columns on each side of the visible image that, presumably, P Pro will not display (Note: P Pro does not add black-bars to NTSC DV SD files, only to Widescreen).

                                                                     

                                                                    So, perhaps the HD to NTSC DV Widescreen Media Encoder transcoding algorithm is not working properly.

                                                                     

                                                                    2) If it is correct to say that there are two types of DV AVI files, then as an update to my previous note...I'm thinking P Pro should interpolate 1920 columns down to 720 (not 704 as I originally wrote before coming to the conclusion that there might be two flavors of AVI files).

                                                                     

                                                                    From my perspective, it would be good if an Adobe P Pro software engineer, who worked on the Media Encoder and who knows how P Pro displays captured DV AVI files and transcoded DV AVI files, would weigh-in on this.

                                                                     

                                                                    Jeff

                                                                    • 31. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                                      Sengstack Community Member

                                                                      Ann wrote: Actually the black bars is empty space. The background shows as black.

                                                                       

                                                                      ==========

                                                                       

                                                                      Not so in my experience. I just exported an AVCCAM (AVCHD) 1920x1080 30p clip to NTSC DV Widescreen and the bars along the left and right sides are black, not transparent.

                                                                      Jeff

                                                                      • 32. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                                        Wil Renczes Adobe Employee

                                                                        Jeff, I already answered your question above (not sure if you skipped over my post).  You're getting tripped up on the notion that the black bars equates to the area outside the production aperture of dv footage, and that's not the case.  This problem has nothing to do with production versus clean aperture of dv.

                                                                         

                                                                        (Tangentially, since you were asking on what you're getting during onscreen dv playback , PPro doesn't expand out production aperture to clean on playback - that would be effectively be a horizontal stretch distortion.  You're getting full 720 width in the program monitor.  If you're wondering why you're not seeing black bars on your DV  footage, it's probably because there isn't any.  Keep in mind that the 'production' aperture might not be visible on a dv camera - you'd have to be capturing from an analog signal to see production aperture.  If you're shooting on a DV device, it's likely to fill the entire width of the available image.)

                                                                         

                                                                        To repeat, the black bars are the difference between your HD aspect ratio (usually 1.5 or 1.33) and the NTSC 16:9 aspect (1.2).  To maintain the 1:1 relationship of the height & width of your HD material, letterboxing is being applied.

                                                                         

                                                                        • 33. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                                          Wil Renczes Adobe Employee

                                                                          robodog2 wrote:

                                                                           

                                                                          Wil,  which is basically putting the HD into DV and scaling it down to fit the 16:9 DV..correct ?

                                                                          Yep, exactly. Minor nuisance, I know, but at least you know exactly what you're getting for output, since you now control the panning. 

                                                                          • 34. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                                            Sengstack Community Member

                                                                            Hi Will, et al,

                                                                             

                                                                            I'm throwing in the towel. It's making less sense now than after the first couple responses.

                                                                             

                                                                            Back then, as I understood it, the issue was that clean aperture was the visible portion of the larger production aperture. And the area outside the clean aperture but inside the production aperture was not displayed in P Pro. Now Will says "P Pro doesn't expand out production aperture to clean on playback." How could P Pro expand out production aperture to clean aperture, when clean aperture lives within the production aperture? At least, until now, I thought the clean aperture was within the production aperture. Now I don't know.

                                                                             

                                                                            Will also wrote in his earlier post about different PARs. He said the "OP question" (I don't know what OP question means) "is why do I get letterboxing?" I don't see what difference, different PARs make. Working with different PARs happens all the time. How about working with 1280x1080 with a 1.5 PAR? If that is output to 1920x1080 with a 1.0 PAR, do the PAR differences create an problem? And PARs for NTSC have been shifting around as engineers figured out that 10/11 is better than .9 and so on.

                                                                             

                                                                            Anyway...I had hoped to be able to figure this out. But now it's clear that short of sitting down with an Adobe Media Encoding software engineer with P Pro and AME open in front of us and a pocket calculator standing by, I don't think I'll be able to make heads or tails of this.

                                                                             

                                                                            Jeff

                                                                            • 35. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                                              Community Member

                                                                              hehe...When you do that...sit down and go through this with SMPTE and NASA and MIT and ADOBE engineers and programmers ----SHOOT VIDEO....document it and edit with graphics and screenshots and math forumulas etc....

                                                                               

                                                                              Then you can bet I will be on line to BUY IT   !

                                                                               

                                                                               

                                                                              • 36. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                                                Sengstack Community Member

                                                                                Will do. Thanks for the chortle.

                                                                                • 37. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                                                  Marcus Koch Community Member

                                                                                  Hi Jeff,

                                                                                   

                                                                                  I just run accross your post. It is old, but I recently was running in the same problems as you. It was hard to get things straight for me, but finally I found a German paper that explained everything just to the point.

                                                                                   

                                                                                  16:9 = 1,777...

                                                                                  HD uses square pixels (PAR=1.0) and if you check the two most common HD video sizes and take your calculator 1920:1080=1,777... and 1280:720=1,777.... So both of them are 16:9 formats. (Exactly we would calculate 1920 (pixel) x 1.0 (PAR) : 1280 (pixel) x 1.0 (PAR))

                                                                                   

                                                                                  Now in SD we have an analog NTSC/PAL an a DV NTSC/PAL. To make it easy first, lets look at DV. The default resolution for DV NTSC is defined as 720×480, but DV doesn't us square pixel. It uses rectangular pixel. The PAR for analog(!) 16:9(!) NTSC is about 1,2154. So to convert DV pixel into the square pixel world you need to calculate 720 (pixel) x 1,2154 (PAR) = 875 square pixel.

                                                                                   

                                                                                  Now we are ready for the surprise: 875:480 = 1,822916...!!! DV NTSC (as PAL) are just not exact 16:9!

                                                                                   

                                                                                  This means you can't transform an HD frame into an SD DV frame without cropping or padding with black bars.

                                                                                   

                                                                                  Old Premiere and AE actually stretched the frame a little to make the transform fit. In AME you really need to choose one of three options: you can have the HD frame cropped, the SD frame padded with black or the SD frame stretched, which would distort the picture a little bit, but not much. If you don't want to have the picuedistorted or have black bars you need to crop off 28 (27) pixels from your HD surce footage. This is why often 14 pixels are each cropped of the top and the bottom. You can do this in AME using the crop tool and set the output "scale to fit".

                                                                                   

                                                                                  So far this explains your problem and shows you the possible solutions. To understand why DV NTSC and PAL are not 16:9 you have to dig a little bit deeper into the analog world. This would take bit longer. For a rough and simple explanation consider that analog TV (NTSC/PAL) has no pixels. It's analog. So ITU-R BT.601 defines how to get analog video into the digital world. The defined sampling frequency results in a NTSC frame of 711×486. Considering the PAR of 1,2154 you get 864:486=1,777.... So analog (anamorphic 16:9) PAL is really 16:9. Analog NTSC video convertd to DV is padded with black bars to fill to 720.

                                                                                   

                                                                                  This all concerns analog to digital SD-TV. The black bars were not shown on CRT TVs due to the overscan area. Nowadays LCD TVs and computer monitors can show the full 720 pixel, but still use overscan. Also video that is recorded digitally is normally recorded with the full 720 pixel. So we have video that is not in 16:9. Therefore you need to handle the transforming either with bars, cropping or distorting.

                                                                                   

                                                                                  Hope this helped you Jeff.

                                                                                   

                                                                                  Marcus

                                                                                  • 38. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                                                    Sengstack Community Member

                                                                                    Hi Marcus,

                                                                                     

                                                                                    Thanks for the thorough and informative explanation.

                                                                                     

                                                                                    Jeff

                                                                                    • 39. Re: Export HD to NTSC Widescreen -- not truly 16:9
                                                                                      HarleyTDavis Community Member

                                                                                      I've seen the phenomena in broadcast.  The math works too.  Here's a little solution I came up with... ...PADD your SOURCE...  Let me explain.  If we have the black bars coming in anyway, as a matter of course, why not simply add that to the source and downscale it a bit before dropping it down to SD output?  This puts a Padding on it in the source area, and cropping afterward doesn't lose footage at the edge.  You may have actually solved a problem I'm dealing with right now with your explanations.  I may go ahead and do this tomorrow when I have time.  You've certainly given me much to think about.

                                                                                      My problem is this:

                                                                                      I am multi-cam editing a 1080 but I want to do so in a 480\486 format so I can output to dvd in a full 16;9(okay, not quite 16;9) format.  I can live with some overscan that gets scaled up when played on a blu-ray player or into a newer HDTV.  I'd like it to be able to play on a 4;3 screen as a panoramic format.  Like I said, I can live with the scaling and padding, no problem.  I prefer it actually.

                                                                                       

                                                                                      My solution for you:

                                                                                      set up your SD sequence, note the size by pixel...  Remember, approximately 2.3% of your image will be padding.  Why not downscale that first in an HD sequence (you know, drop 2.3% in HD instead of blowing up in SD)?  When you crop your image later, you'll lose a little bit of the quality in the image right?  Sure... ...But you introduced noise to begin with in downscale and it should be sharper, and when you crop to upscale it back, you should put even more noise into it without asking... ...What to do?!  Soo much noise...  How about adding a 0.5 or 1% gaussian blur in the output step to wash away the excess noise?  You could run a noise filter before, but that won't get you as accurate a result in the output.  Run the gaussian blur in output at less than 1% (this equates to a sharpening filter with a denoiser in photoshop; basically, blurring the image at less than 1% means that it will blur details that vary extremely little, while leaving larger variances intact.  The smaller the decimal value, the smaller the change in detail it will seek.  At 1, it will smooth out pixels where the change in color is a small, and at greater values than 1, it will seek out more of those greater changes;  Add a decimal to the whole number and it will do a color\luma pass like a standard decimal value, but it will find more of those small changes in the areas it has just smoothed over).  Set your Gauss canon, fire...  You should get a decent quality, better than normal SD, but not quite HD.  The motion might look more natural too.

                                                                                       

                                                                                      Screw it... ...I'm gonna give this a try when I finish my project.  I'll just make a separate set of sequences if you don't mind... ...It would make a great Special Full Frame Edition, but really wouldn't have a great purpose beyond that.

                                                                                       

                                                                                      Just one thing... ...Does anybody know how to get a decent copy of my Markers from one sequence to another, without simply Duping the sequence?  Me neither.  Should work nicely for this one.    All I really have to do is dupe the sequence, replace one video with another, and remake all my cuts.  I'll have to mark each one.