[alsa-devel] [PATCH v2 2/3] route: Select slave chmap based on ttable information

[David Henningsson]

On 02/28/2014 02:49 PM, Raymond Yau wrote:
> 
> 
> 
> 2014-02-28 15:57 GMT+08:00 David Henningsson
> <david.henningsson at canonical.com <mailto:david.henningsson at canonical.com>>:
> 
>     It means we need to initialize this order:
> 
>      1) Read the ttable to figure out which channels are present
>      2) Open slave pcm and find a matching chmap
>      3) Determine size of ttable (this can now depend on the chmap)
>      4) Read ttable coefficients
>      5) At prepare time, select the matching chmap
> 
> 
> Do this patch assume the slave.pcm of the route plugin must have a
> channel map ?

No. In that case, it will fall back to ALSA's standard channel map ( FL
-> 0, FR -> 1, etc).

> are there any side effect when some of sound cards using route but does
> not have channel map ?

If there is no channel map, things should remain unchanged.

> 
> 
> 
> e.g. ice1712,
> 
> 	playback.pcm {
> 		type hooks
> 		slave.pcm {
> 			type route
> 			ttable.0.8 1
> 			ttable.1.9 1
> 			slave.pcm {
> 				type hw
> 				card $CARD
> 			}
> 			slave.format S32_LE
> 			slave.channels 10
> 		}
> 
> 
> rme9652, ....
> 
> slave.pcm {
> 		type route
> 		slave {
> 			pcm {
> 				type hw
> 				card $CARD
> 			}
> 			channels 26
> 		}
> 		ttable.0.24 1
> 		ttable.1.25 1
> 
> 



-- 
David Henningsson, Canonical Ltd.
https://launchpad.net/~diwic