[vlc-devel] [PATCH 1/4] es: move i_profile/i_level to audio and video format structs

Jean-Baptiste Kempf jb at videolan.org
Mon Apr 2 22:48:09 CEST 2018


On Mon, 2 Apr 2018, at 20:52, RĂ©mi Denis-Courmont wrote:
> Yeah so I already answered that question in the email you quoted, I 
> think. If you need to know to decode, then it's not the same syntax and 
> thus not the same codec.
> Of course, this leads to ambiguities, if you havea series of strict 
> subsets. That's when you need to think what makes most practical sense.
> Codecs can be identified by fourcc or by pair of fourcc and profile. 
> It's a design decision how to convey entropy. It makes little/no sense 
> proposing a new profile in audio/video format all the while we regret 
> having RGB masks in addition to fourcc.
> So again, if you need to distinguish the codec/syntaxes, you should use 
> a different fourcc, if only to avoid reproducing the type of problems we 
> have with RGB.
> If you cannot distinguish at input, the you are screwed, with or without 
> an extra profile field. And if it is a multidimensional problem, I am 
> not clear how profile helps over fourcc either.

Thanks for this detailed answer. I'll see with Thomas if we can do something clever about this...

Jean-Baptiste Kempf -  President
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