[alsa-devel] Softvol for Independent Volume Control

[Cameron Barfield]

Is it possible that the Softvol plug in only supports S16_LE and S32_LE formats?



Cameron Barfield wrote:
> Well, I think I am actually on the right track.
> 
> I'm using a Blackfin BF537 with an AD1980BL (AC97) codec. All seems well 
> with it. I'm running it with MMAP and DMIX appears to work beautifully.
> 
> I'm trying to add the volume controls to the mixer so that my 
> application can adjust the volumes of its audio streams.
> 
> I've been playing around with /etc/asound.conf and so far I have:
> 
> pcm.mychan1 {
>     type            softvol
>     slave.pcm       "default"
>     control.name    "mychan1"
>     control.card    0
> }
> 
> I can play WAV files (48K) no problem using aplay -D mychan1 file.wav. 
> If I play any wav/au files that need rate conversion, I get:
> 
> aplay: set_params:904: Sample format non available
> 
> If I don't specify a device for aplay, I can play pretty much any wav/au 
> file I have. DMIX also still works.
> 
> If I adjust the volume of my new channel, it does adjust independently 
> of Master,0 and PCM,0
> 
> Am I just grossly misunderstanding how asound.conf works?
> 
> 
> 
> Cameron Barfield wrote:
>> Hi --
>>
>> I've got an application that receives multiple network audio streams. 
>> Using DMIX, I am able to play back all the streams through my sound card.
>>
>> The problem is that I would like to be able to independently adjust 
>> the volume of each audio stream. Would Softvol work for this? All the 
>> examples I've found only show Softvol working as a replacement for a 
>> master volume control (and that's all I've been able to get it to do).
>>
>> If Softvol won't work for independent volume controls, is there any 
>> other ALSA plugin or API call that I'm missing? Switching to something 
>> like Pulseaudio would probably not be an option since I'm running in 
>> an embedded environment.
>>
>> Regards,
>> Cameron
>>
>>
>