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

Clemens Ladisch
2009-03-10T09:00:29Z

(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