[FFmpeg-user] split 1 stereo channel to 8 mono channels

[Moritz Barsnick]

On Thu, Mar 05, 2015 at 18:01:20 +0800, Tseveendorj O. wrote:

> ffmpeg version 1.2.6-7:1.2.6-1~trusty1 Copyright (c) 2000-2014 the FFmpeg developers
>   built on Apr 26 2014 18:52:58 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)

You do realize that this version is very old, especially feature-wise?

> sudo ffmpeg -i Untitled.avi -vcodec mpeg2video -filter_complex "[0:1:a]channelsplit[a1][a2][a3][a4]" -map 0:v:0 -map "[a1]" -map "[a2]"

What do you need sudo for? Are you reading from or writing to a
location not accessible as a normal user?

That said: 

> I'm trying to split one stereo channel to eight mono channels. I don't know
> it is possible. I tried below command but get error

>From the channelsplit filter documentation, I would say it splits an
input stream into separate mono streams, e.g. stereo into two monos.
Since your audio input is stereo, channelsplit will have two output
streams. Therefore, your [a3] and [a4] are undefined.

You will need to split out the channels:
[0:1:a]channelsplit[left][right]
and then split the desired channel into four (you wrote eight but your
example shows four) identical streams:
[left]asplit=4[a1][a2][a3][a4]

In combination:
[0:1:a]channelsplit[left][right];[left]asplit=4[a1][a2][a3][a4]

(Untested.)

HTH,
Moritz