Problem with MP4/H264 metadata crop values

Shakesbeer

6/25/24, 9:29 AM

I have Ubuntu 20.04 Mate, VLC 3.0.9.2, MPV 0.32.0, MPlayer 1.3.0, AVIdemux 2.7.6.

I have a video file (H264/AAC/MP4) in 16:9 aspect (1024x576p) where the video was accidentaly horizontaly squeezed to 4:3 and letterboxed with black bars at the right and left sides to fill the full 16:9 frame size. I didn't want to re-encode it, so I tried to use MP4 metadata to correct the squeezing and remove the black bars. To do so, I used these two ffmpeg commands:

ffmpeg -i inputfile.mp4 -aspect 235:100 -c copy outputfile.mp4

ffmpeg -i inputfile.mp4 -bsf:v h264_metadata=crop_left=128:crop_right=128:crop_top:0:crop_bottom=0 -codec copy outputfile.mp4

I opened the resulting file with VLC 3.0.9.2, MPV 0.32.0, MPlayer 1.3.0, and AVIdemux 2.7.6 and this was the result:

Only MPlayer showed the new aspect ratio and cropped both sides correctly.
AVIdemux ignored the new aspect ratio but cropped both sides correctly.
MPV showed the new aspect ratio but left the left side uncropped, only the right side was cropped correctly.
VLC showed the new aspect ratio but left the left side uncropped, the right side was cropped but not correctly (it seems that the left value was added to the right value).

I will add a screenshot.

I filed this issue on the VLC and the MPV bug lists. But as always when I do so the developers answer that I have an outdated version of their software (which is a general problem with ubuntu repositories) and that I didn't include all the necessary information. Maybe someone else who is more qualified than me can file a "valid" issue.

Or maybe someone knows how to bypass this issue without envolving the developers (maybe it's not even a bug, but I rather doubt that)

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mp4

mpv-media-player

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Problem with MP4/H264 metadata crop values

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