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Pixel Aspect Ratio Fun: 3 different values PRE gives me, none seem right

May 7, 2013 9:40 AM

I have some JVC Everio files that are widescreen (16:9) and stored as 720x576

 

Media info does not show PAR as far as I can see, however 16:9 is 1024:576

As I have 720 instead of 1024, the PAR I think is 1024/720 = 1.422222

 

I started up a project and selected what seems the right thing PAL -> HD Camcorder -> Widescreen.

(I am not sure if this setting is meant to be what you are importing, or what you want it to end up being....)

 

07-05-2013 18-25-25.png

 

So it says here that PAR is 1.4587 which seems fairly close to what I came up with, so I select this.

 

On importing my first clip however, I notice that I have a smaller than 16:9 screen and that I have black bars in the timeline:

 

07-05-2013 18-17-32.png

 

So I do interpret footage, and it says the PAR from file is 1.0940

That is wrong, so I check "conform to" and have some options, so I select the DV PAL Widescreen 1.4587

 

07-05-2013 18-18-36.png

 

 

Then I have black bars above and below, so I have  a 4:3 widescreen presentation...

 

If I interpret the footage and confirm before I place in the timeline, then it seems ok...

 

However it is very slightly off, and when I play in VLC the original clip is slightly narrower, just enough that it meets my expected 1.422222 instead of the 1.4587...

measuring VLC screen, it is in fact 16:9

 

So in total I have 3 values.

1.422222 from VLC and what I calculated

1.4587 that I asked PRE to use

1.0940 that PRE thinks came from the file

 

1. Why all the differences?

2. Are the opening settings intended to match source or destination?

3. What do I need to do to avoid having to use interpret footage on every clip I import?

 

Many thanks

 

Dave

 
Replies
  • Currently Being Moderated
    May 7, 2013 5:53 PM   in reply to wcn_dave

    Dave,

     

    The story of mod widescreen and Premiere Elements (several other non Adobe programs as well) is a very old story worldwide.

     

    From the PAL perspective.....

     

    SD is 720 x 576 4:3

    SD\widescreen is 720 x 576 with a 16:9 flag that stretches the video for display after encoding.

     

    In the case of JVC's mod widescreen, the 16:9 flag is lost in the transfer or the video editor does not recognize it (depends who you are talking to).

     

    Typically the .mod widescreen 16:9 will present as 4:3. Another problem may be that your video editor may not import it unless you change the .mod file extension to .mpg.

     

    All that being said, many (even in PAL areas) have found success with editing .mod widescreen (MPEG2.mod)

    a. JVC .mod widescreen imported into a Premiere Elements project set for (in your case) PAL DV Widescreen.

    and

    b. If the .mod widescreen present as 4:3 in the Edit Mode Monitor (as it is expected to based on history), then go to Interpret Footage/Pixel Aspect Ratio and dot the Conform to: and select (in your case)

    D1/DV PAL WIdescreen 16:9 (1.4587). There is no other valid choice in this regard.

     

    The Edit Mode Monitor space is established by the your project preset setting of PAL DV Widescreen.. So, that space is representative of PAL DV Widescreen. If there is a bit of that space that is not filled by Interpret Footage/Pixel Aspect Ratio reset, then scale the video to make the fill. What does the video look like?

     

    If you do not get satisfactory results which you should based on the results of others, then convert the .mod widescreen to DV AVI widescreen and try using that as your source media. There is no fix to the matter, short of buying a new camera which does not record .mod widescreen, that will take away the problem so that you do not have to address it for each import.

     

    Please let us know if your questions have been targeted.

     

    Thanks.

     

    ATR

     
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  • Currently Being Moderated
    May 8, 2013 7:24 AM   in reply to wcn_dave

    Dave,

     

    My take on all this is that the keywords here are non square versus square pixels as well as frame aspect ratio (SAR) versus pixel aspect ratio (PAR) versus display aspect ratio (DAR).

     

    Given that your video is shot with a JVC camera with the setting for PAL widescreen (16:9) and that you want to edit it in Premiere Elements.

     

    (a) The properties of such a video would be expected to include: frame size 720 x 576 pixels (SAR) and 16:9 display aspect ratio (DAR). For the moment we will assume that there is no loss of the file’s 16:9 flag that stretches the 720 x 576 for display after encoding.

     

    (b) Before we import that video into Premiere Elements, we need to set a project preset which will direct the program to set up the appropriate space in the Edit Mode Monitor from which to edit. The project preset selected should match the properties of the source media so that the correct space is established in the monitor. That space is the “display” space for the 720 x 576 non square pixels displayed at about 1050 x 576 square pixels. For now we will not go into nor be distracted by whether that display width in pixels should be 1024 or 1050.

     

    http://www.mikeafford.com/blog/2009/03/pal-d1-dv-widescreen-square-pix el-settings-in-after-effects-cs4-vs-cs3/

     

    Based on that introduction, the PAL DV Widescreen is selected as the Premiere Elements for this video. Note that in the description of the project preset it gives Pixel Aspect Ratio = D1/DV PAL Widescreen 16:9 (1.4587). That 1.4587 Pixel Aspect Ratio (PAR) is a correction factor as are all the Pixel Aspect Ratios given in the project presets. In this example, the pixel aspect ratio of the preset corrects the 720 x 576 non square pixels with the 16:9 flag to about 1050 x 576 square pixels.

     

    Now, if you have a .mod widescreen which is being interpreted as 4:3 instead of 16:9 in a Premiere Elements PAL DV Widescreen project, the display space in the monitor is still for the PAL DV Widescreen as per the project preset set.  So, use of the Interpret Footage feature/Pixel Aspect ratio = Dl/DV PAL Widescreen 16:9 (1.4587) should just about supply the appropriate display correction. Choice of Square Pixels (1.0) instead would be expected to display the video as 720 x 576 (720 x 1.0 = 720).

     

    You wrote:

    If I select AVCHD H.264 full HD, import a JVC MOD file, and interpret it, and then export as square pixed SD file, then I assume PRE will take the MOD file and "convert" it to square pixel SD.  So my only outstanding question is: what role / impact does the preset have in all of this?  Sorry if that's a real noob question, however it does puzzle me.

    Check above for the details of the role of project preset in all this. But, if you select PAL/AVCHD/HD 1080i25 (1920 x 1080 16:9 square pixels = 1.0) as the project preset, you will be directing the program to set up a 1920 x 1080 16:9 space in the Edit Mode Monitor. The program is still going to be interpreting your mod widescreen as 720 x 576 with 4:3 for display, and the display would have large black borders to the left and right of the image. If instead you apply Interpret Footage = Square Pixels (1.0) here, you will still have your mod widescreen displayed 720 x 576  in a 1920 x 1080 16:9 space (large black borders to left and right of image.)  If you were to select D1/DV PAL Widescreen 16:9 (1.4587) instead in Interpret Footage in this instance you might expect to see a stretched  out person or picture image with small black borders at the top and bottom of the image.

     

    Please let us know if any of the above helped.

     

    Thanks.

     

    ATR

     
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