[Ffmpeg-devel] Re: [PATCH] non conformance to 3GP format (3GP TS 26.244 v 6.5.0 2006/06) 2nd try

[Baptiste Coudurier]

Baptiste Coudurier wrote:
> Hi
> 
> Michael Niedermayer wrote:
>> [...]
>> what about requireing -strict -1 ?
> 
> Ah, does AVFormatContext support strict ?
> 
> [...]
> 
>> hmm, hmmmmmm :(
>> i still think channel count is the count of channels and not 2 ...
>> so unless this breaks something my vote would be to store the correct
>> number of channels, after all the specs you quote dont say store 2 if
>> there are more then 2 channels they just dont say anything about more
>> then 2 ...
> 
> Ok I think I found the truth:
> 
> Quoting ISO 14496-1 AMD 6 4. Composition:
> "In MPEG-4 both visual and aural composition are done using the BIFS
> system.  Therefore structures marked as "template" in the ISO Base Media
> Format which pertain to composition, including fields such as matrices,
> layers, graphics modes (and their opcolors), volumes, and balance
> values, from the MovieHeaderBox and TrackHeaderBox, are all set to their
> default values in the file format.  These fields do not define visual or
> audio composition in MPEG-4; in MPEG-4, the BIFS system defines the
> composition."
> 
> Since channelcount is mentioned as template it must be left as 2.
> 
> PS: sorry gmane fucked up and I lost one mail. I hope I did not break
> the thread. I now quit using gmane.
> 

Applied with channelcount as 2 for 3gp and mp4.

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