Re: [PATCH v4 21/24] paaudio: channel-map option

[Zoltán Kővágó]

On 2019-09-25 16:13, Gerd Hoffmann wrote:
>    Hi,
>
> > > Oh now that I looked again at the pulseaudio docs, channel-map doesn't
> > > have to be a list, it can be also a "well-known mapping name".
> >
> > Unambiguous because the well-known mapping names are not valid channel
> > position list members.
>
> Do we have well-known mapping names for the common use cases?
> So maybe just support these?
>
> cheers,
>    Gerd

It's surprisingly hard to figure out what are these "well-known names", 
I could only find them in the source:
https://github.com/michaelwu/pulseaudio/blob/16e3dccfa88455ebd329de27a98a3d979a8bdc8e/src/pulse/channelmap.c#L538

It doesn't provide much over the "auto detect channel maps from the 
number of channels" pulseaudio already has (the only ambiguous case is 
surround-41 vs surround-50).  IIRC I originally added this feature 
because USB audio and pulseaudio didn't agree about the order of 
channels, for example in 5.1 pa defaults to 
left,right,rear-left,rear-right,front-center,lfe while USB audio expects 
left,right,center,lfe,rear-left,rear-right order. You can't specify this 
with the well-known names.

Regards,
Zoltan