I have a hypothesis. Would love it if someone could confirm or add information.
Compression quality actually not supported by avc1/hvc1 (h264/h265) codecs. In some systems, like mine, AV Foundation translates compression quality to bitrate. In other systems, like my user's, AV Foundation crashes.
Testing the hypothesis
Write a video with H264 at 40% compression quality
Write the same video with H264 at 100% compression quality
Compare the bitrates with ffprobe
The first video is encoded with a bitrate of 1000 kb/s
The second video is encoded with a bitrate of 25841 kb/s
These results support the hypothesis. The next question is if bitrate is the only thing adjusted when passing a compression quality value. I haven't tested if it changes any of the other compression settings.
Another datapoint is that the docs explicitly say about the compression quality key, "A key to set the JPEG compression quality of the video." which does sound like it's only applicable if the JPEG codec is chosen.
Hat tip to this SO answer
Topic:
Media Technologies
SubTopic:
Audio
Tags: