30 Replies Latest reply on Nov 7, 2008 1:47 PM by joshtownsend

    Exporting 24 fps avi to MPEG2 makes it 29.970 fps?

    Level 1
      I just exported a 23,976 fps avi to MPEG2 choosing MPEG2-DVD 23,976 fps progressive and now when i check the new m2v-file in MediaInfo it says 29,970 fps. How could that be? I know i chose 23,976 fps in the media encoder so that's not it. Anyone have a clue?
      • 0. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
        Jim_Simon Level 8
        The MPEG2-DVD export option adds the necessary pulldown flags required for NTSC viewing. This is normal and nothing to be concerned about.
        • 2. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
          Level 1
          Ok, good to know, thanks Jim!
          • 3. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
            joshtownsend Level 2
            This not right. Every major movie released on DVD is 23.976 and the dvd player adds the extra frames to comply with 29.97 NTSC. http://www.dvdfile.com/news/special_report/production_a_z/3_2_pulldown.htm

            Media encoder gives the option make the dvd 23.97, 29.97 or 29.97 drop frame. If all dvd's had to be 29.97 then there wouldn't be this option. It saves you 20% space on the dvd. I've been making 23.97 dvd for years.

            Premiere cs4 has big problems with 24pa and it sees it as 29.97. This most likely why it shows up like that. Of course cs3 can't read m2v files so you have to check the footage in another program.

            It's a pain and I wish adobe would fix it. Worked fine in cs3.
            • 4. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
              Level 1
              Man, i just upgraded to CS4! Is this really correct, what Josh is saying? So i should just go back to CS3?
              • 5. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                Jeff Bellune Adobe Community Professional
                >Every major movie released on DVD is 23.976 and the dvd player adds the extra frames to comply with 29.97 NTSC

                That is exactly backwards. Newer progressive DVD players read the flags in the file and can perfectly reconstruct the progressive frames from the field-based storage on the disc. The flags also tell the DVD player which fields to repeat to display properly on interlaced NTSC televisions. The DVD player doesn't add any extra frames for 29.97 fps interlaced display.

                Don't believe me? Read the DVD FAQ or pick up a copy of Jim Taylor's DVD Demystified and read Chapter 3.
                • 6. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                  joshtownsend Level 2
                  Well your DVD will play like it should. It's not the that it is encoding the DVD wrong.

                  Think about it. There is are three frame rate options 23.976, 29.97 and 29.97 with drop code. If all DVD's had to be 29.97 why would there be a 23.976 option?

                  I just encoded a 23.976 DVD m2v file then dropped it into my timeline and it showed up as 23.976 like it should. I also burned it and it plays fine on my cheap dvd player.

                  Go into the encoding menu and make sure it's set to 23.976 and not 29.97(drop frame.

                  If you don't believe me that dvd's can be 23.976 and work fine on dvd players just google it. They can it's a fact.

                  The only think I said that was in incorrect was me thinking that the 24pa issue was related to your problem. I tested it and Adobe encodes the dvd to 23.976 and it shows up in the timeline like that.

                  If you use the dvd presets that says progressive it defaults to 29.97. The only preset that defaults to true 23.976 is the 'high quality widescreen 23.976'.
                  • 7. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                    Jeff Bellune Adobe Community Professional
                    >If you don't believe me that dvd's can be 23.976 and work fine on dvd players just google it. They can it's a fact.

                    josh,

                    I didn't say that DVDs couldn't be 23.976. Almost all Hollywood DVDs are. What I am saying is that the video is stored as interlaced 29.97 on disc. Even properly encoded 23.976 footage is stored that way.

                    It is the deinterlacing chip in the player that monkeys with the flags and the fields to produce true progressive output. Sending output to an interlaced display only requires that the player knows which fields to repeat to properly display the 23.976 footage on a 29.97 interlaced TV.

                    IMHO you were implying that it was the player that added frames to the mix to get the footage to display properly on an interlaced television. Maybe I misinterpreted what you were saying?

                    -Jeff
                    • 8. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                      joshtownsend Level 2
                      Wrong man
                      I have links to prove it. From wiki http://en.wikipedia.org/wiki/24p

                      24p on DVD

                      DVDs, however, are capable of storing the native 24p frames. Every Hollywood movie is laid to disc as a 24p (actually 23.976p see below) stream. With a progressive-scan DVD player and a progressive display, such as an HDTV, only the progressive frames are displayed and there is no conversion to an interlaced format eliminating the appearance of any interlace or de-interlacing artifacts. When displayed on a standard NTSC TV (which only display 60i) the DVD player will add 3:2 pulldown to the signal.

                      In traditional television broadcast and VHS, the video stream has 3:2 pulldown added. This material cannot be displayed progressively without the resolution loss of de-interlacing, unless the de-interlacer has accurate cadence detection
                      • 9. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                        joshtownsend Level 2
                        Then answer my question why are there 3 presets? If dvd's had to be 29.97 then why is there a 23.976 preset? How come I can and have been for years encoding the mpeg at 23.976 gaining 20% more space over 29.97 and it works fine on every dvd player I and my clients have tried it on? It says it plain as day on wiki as well as a ton other places the dvd player will ADD 3:2 pulldown to the signal.

                        Try it man. Encode a 23.97 MPEG then put it on a DVD with out going through any other program. It will play fine.

                        Here's another link and quote http://www.dvdfile.com/news/special_report/production_a_z/3_2_pulldown.htm

                        "On each DVD encoded from a film source, a flag is inserted within the MPEG-2 data stream that instructs the player to repeat certain fields to reconstruct the 29.97 frame per second interlaced video. The player obliges by performing the 3:2 pulldown in real-time, continually creating interlaced frame sequences just like the one shown in the above figure, "The Telecine 3:2 Pulldown Process for NTSC Video."This capability enables the player to produce video compatible with conventional displays that were designed based on the NTSC video standard.(As we shall see later, progressive scan DVD players take a different approach.)"

                        Another http://www.allformp3.com/dvd-faqs/140.htm

                        "1- reinterleaving (also called weave ). If the original video is from a progressive source, such as film, the two fields can be recombined into a single frame. "

                        Another http://dvfilm.com/maker/24Pdvd.htm
                        • 10. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                          Jeff Bellune Adobe Community Professional
                          <sigh><br /><br />josh,<br /><br />You have the right idea, you're just expressing it incorrectly.  Your  use of the terminology is smurfed.  I hope whoever reads this thread after today can get past what you're saying to what you really mean.<br /><br />-Jeff
                          • 11. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                            joshtownsend Level 2
                            My terminology is bad and your the one saying smurfed :)

                            How about this for simple
                            A dvd can be made at 23.97 native giving you 20% more room on the dvd than one encoded at 29.97. A dvd doesn't have to be encoded at 29.976 (drop frame or not) to work. If it did then there would be no need for 23.976 option when making a DVD.

                            In the other posts I quoting links and qualifying the above.

                            This one from Panasonic which is clear as day.

                            http://www.panasonic.com/business/provideo/app_dv_24qaboutdv1.asp

                            "At this point in time only a few specialized DVD authoring systems recognize 24p (i.e. 23.976 frames per second) as a valid input signal. Most authoring systems expect to receive an NTSC compatible 60i (i.e. 59.94 fields per second) signal. A 24p sensitive DVD encoder can work 25% more efficiently than with 60i, because it only has to encode 48 fields / 24 frames per second compared to 60 fields / 30 frames per second. For any given Megabit/per second budget, that offers the potential of higher quality DVD encoding. Motion pictures released on DVD are encoded at this lower (24p) frame rate, so a 24p native video DVD (DVD-R / DVD-RAM) should be compatible with the majority of DVD players."
                            • 12. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                              Level 1
                              Seems like something you guys should define is the word "stored". If i understand you both correctly the 24p video doesn't have to be CONVERTED to 30 fps to be burnt on a dvd, and according to josh you get the 20% extra space when burning 24p - but somehow when converted to MPEG2 the video looks like it's 30 fps but with a flag that tells the DVD player that it's not. But then why does it have to look like 30 fps? Why is the video stored AS IF it were 30 fps (even though it's 24p)?
                              • 13. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                joshtownsend Level 2
                                Because most consumer dvd-burning programs like Audition automatically add the extra frames to make it 29.97. Most likely they do this to avoid this type of confusion :)

                                Take the VOB file of a hollywood released dvd and you will see it is 23.976 not 29.97.

                                I'm not meaning to argumentative. Test it yourself encode a DVD MPEG 23.976 then burn the files to a dvd. You won't have a menu but if your dvd player is less than 5 years old it will play the movie. Just remember almost no commercially released DVD are made using encore or any other sub $500 dvd authoring program.

                                Did do like I originally suggested and make sure 23.97 is chosen when you render in AME. When drag the file back into premiere is will show it as being 23.97. This was your original question. DVD players can drop frames and add fields. It's easy to test.
                                • 14. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                  joshtownsend Level 2
                                  Another thing that might be confusing both 23.97 and 29.97 are considered progressive.

                                  Also if your exporting top Blu-ray progressive is not a problem in Encore.
                                  • 15. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                    Level 1
                                    Thanks for all your replies!
                                    It's very late where i'm at so i'll test dragging my movie back into premiere tomorrow back at my office, but in MediaInfo the video is considered 29.97 when it ought to be 23.976 and that's weird but maybe i'll just ignore it for now and live happily ever after. Ignorance is bliss! (for now)
                                    • 16. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                      Dan Isaacs Level 2
                                      I hate to disagree with you Jeff, but I must. Josh is correct here. 24p DVDs are, in fact, stored as progressive frames at 23.976 fps (and they are more efficient). Flags are placed on certain frames -- and these flags tell the DVD player to repeat fields when to allow interlaced display.

                                      An easy way to verify this is to look at a 24p MPEG2 file with G-spot: Pics/s vs. Frames/s vs. Fields/s. You can also see the total number of encoded frames, which should verify that it's encoded as 24p.

                                      Interlaced streams cannot contain pulldown flags. If you open a 24p MPEG-2 stream with G-spot, however, you can view the pulldown flags.

                                      It appears to me that there is some contradiction with the DVD "Demystified" FAQ... I'll quote this other passage that supports exactly what Josh is saying:

                                      For MPEG-2 encoding, repeated fields (B1 and D2) are not actually stored twice. Instead, a flag is set to tell the decoder to repeat the field ... MPEG-2 also has a flag to indicate when a frame is progressive (that the two fields come from the same instant in time). For film content, the progressive_frame flag should be true for every frame
                                      • 17. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                        Jeff Bellune Adobe Community Professional
                                        Sorry, Dan. Your italicized quote corroborates what I said earlier. I am talking about how the video is stored on the disc and not how the source MPEG2 file was encoded.

                                        And as for GSpot, it spends more time reading and interpreting flags than actually analyzing frames. Like Bitrate Viewer before it, you must take its info with a grain of salt. I've seen it incorrectly identify fields/frames in .avi files depending on the codec used. And if it can't properly identify what's going on in an .avi file, the format it was first designed for, then you have to be skeptical about its ability to properly analyze MPEG2, a feature added later.

                                        I stand by my earlier statements.

                                        -Jeff
                                        • 18. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                          Dan Isaacs Level 2
                                          > I am talking about how the video is stored on the disc and not how the source MPEG2 file was encoded

                                          I guess I'm failing to see the distiction between them. AFAIK, the video is stored on the DVD just as it is in the .m2v -- just that it's muxed with audio and other information. For example, you can take an .m2v, author and burn it... then demux the VOB and get back (byte for byte) the .m2v you burned to disk, no?
                                          • 19. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                            Level 1
                                            So Dan, do you also think there's a problem with CS4 handling 24p as Josh stated in his first post? Or, why do you think my video file looks like 29.97 when it's 23.976?

                                            >>I am talking about how the video is stored on the disc and not how the source MPEG2 file was encoded

                                            >I guess I'm failing to see the distiction between them.

                                            So it was a matter of defining the word "stored" - yaay, i understood something! :)
                                            • 20. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                              joshtownsend Level 2
                                              For the record I said I was wrong about the 24p thing. I rendered a 23.97 dvd-mpeg and dropped back in the project and it appeared as 23.97 like it was supposed to. You need to check the advanced render settings. Nearly all the presets default to 29.97.
                                              • 21. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                                Jim_Simon Level 8
                                                I'm going to have to throw my hat into the Dan and Josh ring as well. One of the things I investigated during Phase II of dv2Film testing was whether or not the file on disk actually is 24p.

                                                What I found was that a 24p MPEG2-DVD export (which contains the pulldown flags) was in fact the same size as an MPEG2 24p export (without the flags). The MPEG2 30i export was noticeably larger, as one would expect since actual pulldown is being added, not just flags.
                                                • 22. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                                  Jeff Bellune Adobe Community Professional
                                                  Okay, it seems I am guilty of muddying the waters here every bit as much as josh. Semantics got involved and my message was as confusing as I said that josh's argument was. Josh and Juri, I apologize for getting off-topic. Jim and Dan, we can take this off-list if you want to discuss it further.

                                                  The ultimate goal of my input was to point out 2 things:

                                                  1 ) It is possible to have 24p material stored on a 29.97 NTSC DVD disc. That's good news for videophiles who have the proper equipment.

                                                  2 ) Don't worry if some program interprets your 23.976 progressive MPEG2 DVD footage as 29.97. There are reasons that happens, but none of them affect the fact that you really have created a 23.976 video clip, and that is what your audience will have when they play back your DVD. After that, it's up to *their* playback chain to properly display the video.

                                                  -Jeff
                                                  • 24. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                                    joshtownsend Level 2
                                                    Wish you'd stop saying I'm confusing people. Dan and Jim aren't confused.

                                                    Tell me the difference between a DVD that is made with each of the 3 setting. 23.976, 29.97 drope frame, 29.97.

                                                    23.976 - records a 23.976 stream giving more space for a better encode. Has flags telling the dvd player what fields to duplicate to so you seeing 23.976p.

                                                    29.97 with drop code - records a 29.97 stream, giving giving the player flags that tell it what's fields to take away so your seeing 23.976p.

                                                    29.97 non-dropframe - records a 29.97 stream and that's what you see.
                                                    • 25. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                                      Jeff Bellune Adobe Community Professional
                                                      >Wish you'd stop saying I'm confusing people. Dan and Jim aren't confused

                                                      Dan and Jim's level of technical knowledge and expertise is far above the norm.

                                                      Until post #24, your arguments (and my counter-arguments) were, I believe, very confusing to an average user trying to figure out what's going on with 24p video that's to be authored on an NTSC DVD.

                                                      I tried to summarize the essential points of this issue in my post #22. I even apologized to you and Juri in that post for making things worse by trying to argue semantics.

                                                      Your post #24 is also a good summary of what's going on.
                                                      • 26. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                                        joshtownsend Level 2
                                                        It's all cool man. Apologize for if I came across as grumpy. I was floored when I heard about the 24PA frame support not being fixed for 4-6 months. Sorry.
                                                        • 27. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                                          Dan Isaacs Level 2
                                                          > 29.97 with drop code - records a 29.97 stream, giving giving the player flags that tell it what's fields to take away so your seeing 23.976p

                                                          I do not think this is correct. AFAIK, such flags do not exist or (at very least) are not part of the MPEG-2 or H.264 standards.
                                                          • 28. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                                            Jim_Simon Level 8
                                                            Calling it "drop-frame", whatever the setting actually does, is a little strange. In the video industry, drop-frame has a very definite meaning relating to timecode, which has no bearing on the video stored on disk.

                                                            So Adobe has either made an irrelevant preset, or they're using a different definition for drop-frame in this case, either of which is bound to confuse people.
                                                            • 29. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                                              Dan Isaacs Level 2
                                                              > Calling it "drop-frame", whatever the setting actually does...

                                                              Exactly. Very strange. I know what "drop frame" timecode is, but I've got no idea how this relates to export settings for MPEG-2.
                                                              • 30. Re: Exporting 24 fps avi to MPEG2 makes it 29.970 fps?
                                                                joshtownsend Level 2
                                                                Wanna see strange. Export the same clip with each setting. Compression is different between the 23.97 and 29.97 and there's an extra frame. Can't tell if it's better or worse but the pixels are different between the two clips. Makes no sense.

                                                                Isn't there someone that works for Adobe that can explain all this? Why three different presets?