[pulseaudio-discuss] how to pass correct channel map

[Sean Greenslade]

On Wed, Sep 15, 2021 at 09:59:00PM +0530, Vijendar Reddy Mukunda wrote:
> Hello,
> 
> I was just experimenting with a null sink.
> I have created null sink with 48000Hz sample rate, s16le, channels as 6.
> Tried to record from null sink monitor source.
> But when i run parecord command, I am seeing the below error.
> Warning: failed to write channel map to file.
> I have also tried null sink creation
> with channel_map=front-left,front-right,rear-left,rear-right,front-center,lfe.
> But no luck.
> Need inputs on fixing this channel map issue.

That error is just a warning, and can most likely be ignored. Not all
sound formats actually support writing the channel map into them. In
fact, according to the libsndfile docs, only AIFF and CAF are supported:

https://libsndfile.github.io/libsndfile/command.html#sfc_set_channel_map_info

What file format are you using?

--Sean