Open mootari opened 3 years ago
Also, I believe I ran into the same issue in the past when capturing directly via Quicktime.
I could confirm SAR as the root issue for Twitter's encoding problems by changing it via ffmpeg.
Changing SAR on a previously broken video and reuploading it, the greenish tint is gone:
ffmpeg -i bw3-scaled.mp4 -c copy -bsf:v h264_metadata=sample_aspect_ratio=1 bw3-scaled-sar1.mp4
Vice versa, changing SAR for a correctly reencoded video produced the tint when reuploading:
ffmpeg -i bw4-1200x1200-s540x540.mp4 -c copy -bsf:v h264_metadata=sample_aspect_ratio=3234/3235 bw4-1200x1200-s540x540-sar3234-3235.mp4
Oops, this is the wrong repository, sorry! Can you please move this issue over to https://github.com/wulkano/Kap?
Steps to reproduce:
1:1
.ffprobe -show_data
, which should output: 800x798 [SAR 1:1 DAR 400:399]
400
, reexport, check SAR: 400x400 [SAR 400:399 DAR 400:399]
So it seems to be the clip resizing that's messing up the aspect ratio.
Appreciate the detailed issue @mootari!
When the capturing area was defined via the mouse, the resulting MP4 export may have an SAR (sample aspect ratio) other than 1:1. When uploading such a video to Twitter, the reencoded video will show a noticable discoloration (greenish tint).
Note that this may only be reproducible on Retina displays, where the capture area resolution does not match the final video resolution. I'm still trying to come up with reliable reproduction steps.
Partial screenshot of tweet with reencoded video:
I've temporarily shared some examples here (some even reencoded via Handbrake): https://twitter.com/iratoom
The respective ffprobe output (
ffprobe -hide_banner -show_data
) shows: