[FFmpeg-devel] [RFC] Channel layouts

Benjamin Larsson banan
Fri Aug 29 11:08:03 CEST 2008

Peter Ross wrote:
>> permutation table to match the internal FFmpeg channel order. I'm not 
>> sure how well that would fit for most decoders. One other option would 
>> be to decode in codec native order and then pass a channel permutation 
>> table via some means. I'll look into what would work best with dca.
> If that is correct then all decoders and encoder need a channel order
> Why not perform the permutation inside the decoder?

Yeah, the issue I'm hinting at is that you might only know how to 
reorder after you decoded the samples and that you would need to do a 
memcopy to rearrange the order.

>>> Is there any benefit to doing all the bit shifting of the flags or can
>>> we just do the usual 0x1, 0x2, 0x4, 0x8, 0x10, 0x20... that we use for
>>> other bit mask flags?
>> I think we just should add the relevant channel mask instead having this 
>> shifting.
> If you can suggest another method to associate an ascii name to each channel
> masks (for the purpose of user friendly i/o), then I am happy to change...

Well we could just add another table. But that is not a large issue.

Benjamin Larsson

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