[Ffmpeg-devel] Re: ffmpeg "wide" atom

Baptiste Coudurier baptiste.coudurier
Tue Aug 22 23:20:29 CEST 2006


Michael Niedermayer wrote:
>>> [...]
>>> I couldn't find anything about the "wide" atom/box in the MPEG 4 spec,
>>> it seems only be  mentioned in the QuickTime File Format.
>> I didn't find anything either. Attached patch always write 64 bit mdat
>> atom instead of using 'wide' atom.
> maybe mp4 doesnt mention "wide" but it should IMHO mention someting like
> "unknown atoms must be ignored" without that iso could never add a new
> atom without breaking all existing demuxers, that seems unlikely to me


> furthermore always writing a 64bit mdat will break demuxers which dont
> understand it
> [...]

And writing 'wide' breaks demuxers which dont understand it either, it
seems. What is the proportion of demuxers not supporting 'wide' and
demuxers not supporting 64bit mdat, which is required to demux files >
4gb. Also IMHO, creating atoms not existing in specs is doing something
non standard compliant.

What should we adopt ? Again I feel lost about policy. Workaround for
demuxers ?  There is already a workaround for ipod/mplayer which needs a
fake 'mp4a' atom in 'wave' one.

Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
SMARTJOG S.A.                                    http://www.smartjog.com
Key fingerprint                 8D77134D20CC9220201FC5DB0AC9325C5C1ABAAA
Phone: +33 1 49966312

More information about the ffmpeg-devel mailing list