rohit khali (12022-07-21): > I have a query regarding channel layout in the FFmpeg decoded audio stream. > Using below example to explain my question: > > As per ATSC A/52:2012, *coded channel layout* in a 5.1 E-AC3 stream is [L, > C, R, Ls, Rs, LFE]. > For the same stream FFmpeg reported channel layout is [5.1(side):FL FR FC > LFE SL SR]. > If we see here, the position of channels 'C, R, Ls, Rs and LFE' are > different. > > Does FFmpeg reposition channels while decoding as per the standard FFmpeg > channel layout [FFmpeg -layouts]?
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. A decoder will reconstruct each channels, and the order in which it outputs them to the application is an unimportant implementation detail. For example, the audio hardware of a PC makes a different choice of order than both FFmpeg and what you quoted above, and I am pretty sure the kernel driver reorders to unify the order for different hardware. FFmpeg decodes audio and gives you the channels flagged in the channel layout in the order documented by FFmpeg. What you do with them then is your task. Note that when the decoder produces planar output, the reordering is computationally tiny. Regards, -- Nicolas George _______________________________________________ Libav-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/libav-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
