[Matroska-devel] MVC codec in Matroska container

Moritz Bunkus moritz at bunkus.org
Fri Dec 14 11:31:21 CET 2012


Hey,

On Fri, Dec 14, 2012 at 11:27 AM, Mike Chen <mike at makemkv.com> wrote:

> I thought about this as well but came to opinion that this is not
> necessary as the length is bound to be below 64K so the first two
> bytes of the extension are always two zeros and they are bound to be
> different from any avcC extension.

I fear somewhat that programmers might not be aware that the chroma
information might exist in a file. We should definitely include at
least that piece of information in the official specs. That's why I
made the proposal with a 'CPex' identifier.

> But if we go this way we might wrap all data after avcC in the full
> mp4 box as well, by adding length of entire CPex structure before
> CPex. This would remove any ambiguity and make parsing of atom list
> somewhat easier as length will be double-confirmed.

The length of CPex is implicitely given by length(CodecPrivate) -
position(CPex) - 4.

Kind regards,
mosu


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