[Libav-user] AV_CH_LAYOUT_NATIVE usage

[rohit khali]

Thanks a lot for quick response Nicolas!
Yes, I remember our earlier conversation on thread "FFmpeg channel layouts".

Today, actually after a gap I was resuming on mapping the decoded data as
per metadata info (as per the codec standard) and FFmpeg provided channel
layout.
In my case, I know the exact input codec standard so I was thinking to map
standard defined channel order with FFmpeg provided one with a sort of
custom implementation as we had concluded last.

However, just then I came across AV_CH_LAYOUT_NATIVE option which seems to
do something as well with a couple of 6ch AAC streams I tried with. I could
see the channel ordering being changed in Audacity by looking at the
waveform of decoded PCM. Hence today's questions.


Being more involved in video, I do not have much idea in audio encoding. So
my sincere apologies for repeating our last conversation in this thread a
bit.
When you say that "When the audio is compressed, there is no order of
channels, the channels are encoded together to use the fact that they
contain usually a lot of similarity.". My question is what are the standard
defined channel order then? Example: As per ATSC A/52:2012, *coded channel
layout* in a 5.1 E-AC3 stream is [L, C, R, Ls, Rs, LFE] ?
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