Re: Volume per voices [Feature Request]

[Raymond <rayau@netvigator.com>]

Takashi Iwai wrote:
> At Thu, 28 Jul 2005 19:51:16 +0200 (CEST),
> Giuliano Pochini wrote:
> 
>>>>In my driver we have A analog channels and D digital channels. The
>>>>driver registers a "PCM Playback Volume" control as an array of
>>>>A+D integers, where each element is the gain (-128..+6) of each
>>>>channel, but they don't map directly to the PCM channels because
>>>>the driver exports analog and digital channels as two separate
>>>>devices (this feature can be removed easily). So pcmvol[0..A-1]
>>>>controls the volume of hw:0,0 and pcmvol[A..A+D-1] controls the
>>>>volume of hw:0,1. Furthermore, the user can open hw:0,0,x to
>>>>address the xth channel.
>>>
>>>As far as I can see, no driver actually uses the subdevice (substream)
>>>field for PCM substreams; probably because this would require a
>>>separate control for each substream instead of using an array.
>>
>>My case is even more compicated because one ctl controls the volume of two
>>devices. A callback that gets snd_pcm_substream_t* and returns {int numid,
>>firstindex, lastindex} or sort of would make things much simpler wrt hw
>>controls. In case there are both hw volume and softvol, which has
>>priority ? :)
> 
> 
> Returning a list of controls would be simplest as the lowlevel API.
> The higher level API decides which control to use, for example,  while
> h/w specific apps can use the lowlevel API to get certain controls
> directly.
> 
> 

For those controls with SNDRV_CTL_ELEM_IFACE_PCM , ctl->id.device and 
ctl->id.subdevice.

Is it feasible to have a function which return snd_pcm_substream_t* of 
the PCM substream with parameters (snd_kcontrol_t *kcontrol, int device 
,int subdevice)  ?

The topology which the hardware mixers are connected depends on the 
number of channels (mono,stereo,quad,..) of the PCM substream




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