[alsa-devel] [PATCH] [SOUND] recording gain control

[Clemens Ladisch]

(CC alsa-devel)

Viral Mehta wrote:
> Hi,
> 
> I am trying to do gain control while RECORDING for my Audio Mic device.
> 
> My application opens /dev/mixer device and calls ioctl(fdmixer, 
> MIXER_WRITE(SOUND_MIXER_MIC), ...)
> 
> But, the call fails. It traces to sound/core/oss/mixer_oss.c file and 
> snd_mixer_oss_put_volume1() function.
> It never falls in "if (slot->present & SNDRV_MIXER_OSS_PRESENT_CVOLUME)" 
> as condition "if (slot->present & SNDRV_MIXER_OSS_PRESENT_PVOLUME) " 
> comes as false.
> 
> I think there is a bug in kernel and I think it should be like as below,
> 
> --- sound/core/oss/mixer_oss.c  2008-12-03 13:24:02.000000000 +0530
> +++ sound/core/oss/mixer_oss.c   2009-03-09 16:22:06.548766896 +0530
> @@ -688,7 +688,7 @@ static int snd_mixer_oss_put_volume1(str
> 
>      if (slot->present & SNDRV_MIXER_OSS_PRESENT_PVOLUME) {
>              snd_mixer_oss_put_volume1_vol(fmixer, pslot, 
> slot->numid[SNDRV_MIXER_OSS_ITEM_PVOLUME], left, right);
> -               if (slot->present & SNDRV_MIXER_OSS_PRESENT_CVOLUME)
> +       } else if (slot->present & SNDRV_MIXER_OSS_PRESENT_CVOLUME) {
>                      snd_mixer_oss_put_volume1_vol(fmixer, pslot, 
> slot->numid[SNDRV_MIXER_OSS_ITEM_CVOLUME], left, right);
>      } else if (slot->present & SNDRV_MIXER_OSS_PRESENT_GVOLUME) {
>              snd_mixer_oss_put_volume1_vol(fmixer, pslot, 
> slot->numid[SNDRV_MIXER_OSS_ITEM_GVOLUME], left, right);

Your mailer mangled the patch; see linux/Documentation/email-clients.txt.


Best regards,
Clemens