Changing PAR (pixel aspect ratio) in mov file

[rgr]

I accidentally recorded the file in VirtualDub in avi format instead of mov (ProRes).

How to copy it to a mov file (it's easy using ffmpeg with -c copy), but at the same time change PAR to 12/11 (I can do this for mp4, but it doesn't work here). -aspect only changes DAR.

[poisondeathray]

https://mediaarea.net/MOVMetaEdit

PAR editor only works with CLI version

MOVMetaEdit --par 12:11 input.mov

[rgr]

It works, but probably not as it should. The image is now skinny

Summary:
OK = file is correctly detected and does not need to be modified ('Yes') or is correctly detected and need to be modified ('Mod') or is correctly detected and need to be modified but not supported ('No') or there was a problem with it (empty)
PAR = PAR atom is not present ('No'), not present but can be (or is) inserted ('Can'), present and can be (or is) modified (value of the old PAR)
PAR|M = PAR will be modified ('Y') or should be modified but it is not possible due to feature not implemented ('N')
w-scale = (old) width scale of the picture
w-scale|M = w-scale will be modified ('Y')
| OK| PAR|M|Width|w-scale|M|
out.mov|Yes| 9:10| | 720| 1.000| |

[Selur]

If you keep storage aspect ratio (SAR) the same, and you change the DAR (display aspect ratio) you also change the PAR (pixel aspect ratio).
Thus, if your source is displayed properly, and you change the PAR or DAR till will get distorted unless you re-encode and also change the storage aspect ratio (SAR).

https://en.wikipedia.org/wiki/Pixel_aspect_ratio

[rgr]

Link to the correct version of the program:
https://mediaarea.net/download/snapshots/binary/movmetaedit/20240413/MOVMetaEdit_CLI_1...indows_x64.zip

With this version, PAR change works properly.

[hydra3333]

(I can do this for mp4, but it doesn't work here)

Hi. Can you please tell how to set the DAR in ffmpeg when using ffmpeg with `-c:v copy` ... is it `-vf "setdar=16/9"` which works or does it fail ?


edit:

Oh.
1. cannot use filtering like '-vf "setdar=16/9"' with 'c:v copy'
2. bitstreamfiltering '-bsf:v h264_metadata=' does not have a Display Aspect Ratio (DAR) option, one has to calculate the Sample Aspect Ratio (SAR) and use that.

ChatGPT just told me:


edit 2: IGNORE THIS BIT, ChatGPT fibs.

Yes, you can use variables in ffmpeg to calculate SAR dynamically. You can use the variables $width and $height to refer to the width and height of the input video respectively. Here's how you can do it for 4:3:
This command dynamically calculates the SAR based on the dimensions of the input video, which allows you to adjust the DAR without re-encoding and without needing to know the exact resolution in advance.

ffmpeg -i input.mp4 -c:v copy -bsf:v h264_metadata=sample_aspect_ratio=$((4*$height)):$((3*$width)) output.mp4

$((4*$height)) calculates the numerator of the SAR, which is 4 times the height of the video.
$((3*$width)) calculates the denominator of the SAR, which is 3 times the width of the video.

-c:v copy

ensures that the video stream is copied without re-encoding

-bsf:v h264_metadata=sample_aspect_ratio=$((4*$height)):$((3*$width))

applies the h264_metadata bitstream filter to set the sample aspect ratio using the dynamically calculated values for 4:3 DAR and the video's width & height

For a 4:3 DAR, you can use the formula to calculate SAR. Assuming the height and width of your video are standard (480p or 720p), you can calculate the SAR accordingly. For example:
For 720p (1280x720): SAR = 4:3 * (720/1280) = 4:3 * 0.5625 ≈ 4:3 * 9:16 = 9:12
For 480p (640x480): SAR = 4:3 * (480/640) = 4:3 * 0.75 = 3:4

So, for a 720p video, you would use SAR 9:12:

ffmpeg -i input.mp4 -c:v copy -bsf:v h264_metadata=sample_aspect_ratio=9:12 output.mp4

And for a 480p video, you would use SAR 3:4:

ffmpeg -i input.mp4 -c:v copy -bsf:v h264_metadata=sample_aspect_ratio=3:4 output.mp4

For PAL 576p resolution, which typically has dimensions of 720x576, use SAR 32:27.
Here's the ffmpeg command to set the SAR dynamically for a PAL 576p video:

ffmpeg -i input.mp4 -c:v copy -bsf:v h264_metadata=sample_aspect_ratio=32:27 output.mp4

Adjust the SAR value accordingly based on your video's resolution to achieve the desired 4:3 DAR.

[rgr]

ffmpeg -i in.mp4 -c copy -bsf:v "h264_metadata=sample_aspect_ratio=x/y" out.mp4