[Ffmpeg-devel] Re: [PATCH] x264 avc encoding, movenc avcC, ctts

Richard S. teetrinker
Sun Feb 19 19:17:46 CET 2006

Baptiste COUDURIER schrieb:
> Richard S. wrote:
>> Baptiste COUDURIER schrieb:
>>> movenc_ftyp.patch
>>> which makes ftyp atom always written, 'qt  ' is good for MOV files
>>> (according to FCP), 'mp42' is conformed to what ffmpeg produce for mp4
>>> files.
>> Maybe "isom" should be used for ftyp? If "mp42" or "mp41" is used, there
>> should be a IOD and a  correct BIFS/OD Track in the mp4 file.
>> Richard
> I got here a sample produced by FCP which does not contain 'iods' atom.
> I consider FCP being the reference, so 'iods' is not needed when 'mp42'
> ftyp is used.
Quote 144496-4 Conformance testing:

3.7   MP4 File Format
3.7.1  Writing

A valid MP4 file with no tracks has at least: moov, mvhd. If it is a
presentation or the target of an OD URL, an iods is required, containing
an IOD or OD respectively. Only MP4 files used in editing (as the arget
of a data reference URL) may lack the IOD.
Any track must contain: trak, tkhd, mdia. A mdia must contain mdhd,
hdlr, and minf. A minf must contain a suitable media header, a dinf and
a stbl. dinf must contain dref; and a stbl must contain stsd, and if
there are any samples, an stts, stsz, stco, stsc.
The sample table entries must be consistent about the number of samples
in a track.
Extensions should use the UUID mechanism. Track identifiers must be
unique within the file.
The containment hierarchy defined in the specification must be followed.
Very few atoms (for example, user data and UUID extension) are allowed
to occur in multiple containers.
Fields marked reserved should be written to the standard value.
A presentation must contain at least a BIFS track, referenced by the IOD
(as in the systems specification).

A mp4 file with audio and video is a presentation.


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