mp4ff-info error "stpp size mismatch in stsd: 62 - 64" in a webvtt fragmented mp4 input file about mp4ff HOT 2 CLOSED

Thanks for reporting the issue and providing an example file.

stpp is indeed supported, but the standard was wrongly interpreted for the optional fields which were not set in your asset. The issue is fixed in PR #229.

However, the stpp sample descriptor is used for TTML/EBU-TT-D/IMSC fragmented subtitles and not WebVTT so the subject of this Issue is wrong.

The fragmented WebVTT format is called wvtt and is better supported in the mp4ff library in the sense that all its actual payload boxes are supported, and there is a special tool mp4ff-wvttlister to list the text cues from wvtt files.

from mp4ff.

Thanks, true I had to write TTML.xml subtitles fragments instead of WebVTT. mp4ff-info.exe works now fine.

from mp4ff.