Re: [hackers] [PATCH] volume: compute volume by alsa api on linux

From: Ryan <alrayyes_AT_gmail.com>
Date: Tue, 2 Apr 2019 11:30:37 +0200

Works great! There's just still one issue as far as I can see. How do you
select a mixer when you have multiple cards (for example usb Microphone in)?

On Tue, Apr 2, 2019 at 3:11 AM Doan Tran Cong Danh <congdanhqx_AT_gmail.com>
wrote:

> From: Đoàn Trần Công Danh <congdanhqx_AT_gmail.com>
>
> There's a non-posix assignment inside config.mk,
> but it's supported with both gmake and bmake.
>
> var != shell command
> ---
> components/volume.c | 59 +++++++++++++++++++++++++++++++++++++++++++++
> config.def.h | 1 +
> config.mk | 3 ++-
> 3 files changed, 62 insertions(+), 1 deletion(-)
>
> diff --git a/components/volume.c b/components/volume.c
> index 61cec90..eeb3975 100644
> --- a/components/volume.c
> +++ b/components/volume.c
> _AT__AT_ -1,5 +1,6 @@
> /* See LICENSE file for copyright and license details. */
> #include <fcntl.h>
> +#include <limits.h>
> #include <stdio.h>
> #include <string.h>
> #include <sys/ioctl.h>
> _AT__AT_ -72,6 +73,64 @@
>
> return bprintf("%d", m ? 0 : v * 100 / 255);
> }
> +#elif defined(__linux__)
> +#include <alsa/asoundlib.h>
> +#include <alsa/control.h>
> +
> +#define SOUND_CARD "default"
> +#define MIXER_IDX 0
> +
> +const char*
> +vol_perc(const char *mixer)
> +{
> + snd_mixer_t* handle;
> + snd_mixer_elem_t* elem;
> + snd_mixer_selem_id_t* sid;
> + snd_mixer_selem_channel_id_t c;
> +
> + int emute, muted = 0;
> + long minv, maxv, elemv, vol = LONG_MIN;
> + const char *result = NULL;
> +
> + snd_mixer_selem_id_alloca(&sid);
> +
> + //sets simple-mixer index and name
> + snd_mixer_selem_id_set_index(sid, MIXER_IDX);
> + snd_mixer_selem_id_set_name(sid, mixer);
> +
> + if ((snd_mixer_open(&handle, 0)) < 0)
> + goto out;
> + if (snd_mixer_attach(handle, SOUND_CARD) < 0 ||
> + snd_mixer_selem_register(handle, NULL, NULL) < 0 ||
> + snd_mixer_load(handle) < 0 ||
> + !(elem = snd_mixer_find_selem(handle, sid)))
> + goto cleanup;
> +
> + snd_mixer_selem_get_playback_volume_range(elem, &minv, &maxv);
> +
> + if(minv == maxv)
> + goto cleanup;
> +
> + for (c = 0; c <= SND_MIXER_SCHN_LAST; ++c)
> + if (snd_mixer_selem_has_playback_channel(elem, c)) {
> + if (!snd_mixer_selem_get_playback_volume(elem, c,
> &elemv)
> + && elemv > vol)
> + vol = elemv;
> + if (!muted
> + && !snd_mixer_selem_get_playback_switch(elem,
> c, &emute))
> + muted = !emute;
> + }
> + if (minv > vol || maxv < vol)
> + goto cleanup;
> +
> + result = bprintf("%d%% [%s]",
> + (200 * (vol - minv) + maxv - minv) / (maxv -
> minv) / 2,
> + muted ? "off" : "on");
> +cleanup:
> + snd_mixer_close(handle);
> +out:
> + return result;
> +}
> #else
> #include <sys/soundcard.h>
>
> diff --git a/config.def.h b/config.def.h
> index e06be66..40f0a28 100644
> --- a/config.def.h
> +++ b/config.def.h
> _AT__AT_ -58,6 +58,7 @@ static const char unknown_str[] = "n/a";
> * uptime system uptime NULL
> * username username of current user NULL
> * vol_perc OSS/ALSA volume in percent mixer file
> (/dev/mixer)
> + * mixer name on
> Linux (Master)
> * wifi_perc WiFi signal in percent interface name
> (wlan0)
> * wifi_essid WiFi ESSID interface name
> (wlan0)
> */
> diff --git a/config.mk b/config.mk
> index 3b32b7c..6903fe1 100644
> --- a/config.mk
> +++ b/config.mk
> _AT__AT_ -14,7 +14,8 @@ X11LIB = /usr/X11R6/lib
> CPPFLAGS = -I$(X11INC) -D_DEFAULT_SOURCE
> CFLAGS = -std=c99 -pedantic -Wall -Wextra -Os
> LDFLAGS = -L$(X11LIB) -s
> -LDLIBS = -lX11
> +ALSALIBS != [ Linux = `uname -s` ] && printf "%s" "-lasound"
> +LDLIBS = -lX11 $(ALSALIBS)
>
> # compiler and linker
> CC = cc
> --
> 2.21.0
>
>
>
Received on Tue Apr 02 2019 - 11:30:37 CEST