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

[Måns Rullgård]

Luca Abeni <lucabe72 at email.it> writes:

> Hi Baptiste,
>
> I do not know anything about .mov files and about the MOV muxer, but I
> think the "codec" part of your patches (x264_avc_nal_encode.patch) might
> be incorrect:
>
> On Sun, 2006-02-19 at 18:23 +0100, Baptiste COUDURIER wrote:
> [...]
>> x264_avc_nal_encode.patch
>> 
>> which encodes nals correctly for AVC and write extradata for avcC atom.
> BTW, what is AVC? I was under the impression that AVC (Advanced Video
> Coding) = MPEG4 Part 10 = H.264... So, I cannot understand the "encode
> nals correctly for AVC" part

Yes, AVC = MPEG4 part 10 = H.264.  It is occasionally also referred to
as JVT, and in some older sources as H.26L.  There seems to be a
fairly widespread misbelief that AVC is a special variant of H.264
found in quicktime files.  This is incorrect.  There seems to be a lot
of confusion surrounding this codec.  In the broadcast industry, MPEG4
has become synonymous with H.264, the old MPEG4 (part 2) being rarely
used.

> Again, I apologize if I am misunderstanding something, but my impression
> is that your patch does at codec level something that should be done at
> format level... I see "avcC" cited in your libavcodec/x264.c patch, but
> I think it really is a MOV thing? Or am I wrong?

The problem is that various containers define their own format for the
H.264 extradata.  If everybody realized that codecs and containers
should be defined independently, the world would be a happier place.
For some reason, I doubt this is going to happen.

-- 
M?ns Rullg?rd
mru at inprovide.com