[FFmpeg-devel] FFMPEG/GPAC compatibility for mp4 'text' box

David Conrad lessen42
Mon Oct 11 22:46:05 CEST 2010

On Oct 11, 2010, at 5:40 AM, Romain Bouqueau wrote:

> Dear FFMPEG developers,
> I am a GPAC (gpac.sourceforge.net) maintainer, trying to make our frameworks compatible :)
> This mail concerns the implementation of the Apple-specific 'text' box. We implemented it following this specification: http://developer.apple.com/library/mac/#documentation/QuickTime/QTFF/QTFFChap3/qtff3.html#//apple_ref/doc/uid/TP40000939-CH205-BBCJAJEA
> FFMPEG generates streams using this 'text' box. However this leads to "extra NULL bytes" at the end of 'text' boxes which are inconsistent with the above mentioned spec.
> Can any of you give me a pointer to the specification your implement is based on?

I wrote muxing so that -scodec copy from QuickTime-generated files would produce essentially the same stsd atom and samples. Is something setting the extradata size too large?

> Or can you give me the contact to the developper of this part? I found these related commits using svn-blame: r11638 (reimar), r16531 (conrad).

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