Hello

I have a USB headset, where when plugged in, a volume setting is set on playback and capture channels using the ctl interface for the device. After the volume is set I open the capture interface. but I have i have a 2-3 sec. delay that i just don't understand.

I might need to use another solution, but these are difficult to find. The Headset is a plantronics.

The code is listed below.

#include <alsa/asoundlib.h>

#define qDebug printf void set_default_volume(const char *a_hw_dev, int a_percent) { int err; snd_mixer_t *handle; snd_mixer_selem_id_t *sid; snd_mixer_elem_t *elem; snd_mixer_selem_id_alloca(&sid);

if ((err = snd_mixer_open(&handle, 0)) < 0) { qDebug("Mixer open error: %s\n", snd_strerror(err)); return; } if ((err = snd_mixer_attach(handle, a_hw_dev)) < 0) { qDebug("Mixer attach %s error: %s\n", a_hw_dev, snd_strerror(err)); snd_mixer_close(handle); return; } if ((err = snd_mixer_selem_register(handle, NULL, NULL)) < 0) { qDebug("Mixer register error: %s\n", snd_strerror(err)); snd_mixer_close(handle); return; } err = snd_mixer_load(handle); if (err < 0) { qDebug("Mixer %s load error: %s\n", a_hw_dev, snd_strerror(err)); snd_mixer_close(handle); return; } for (elem = snd_mixer_first_elem(handle); elem; elem = snd_mixer_elem_next(elem)) { snd_mixer_selem_get_id(elem, sid); qDebug("Simple mixer control '%s',%i\n", snd_mixer_selem_id_get_name(sid), snd_mixer_selem_id_get_index(sid));

if (snd_mixer_selem_has_playback_switch(elem)) { snd_mixer_selem_set_playback_switch_all(elem, 1); //unmute }

if (snd_mixer_selem_has_playback_volume(elem)) { long min, max; snd_mixer_selem_get_playback_volume_range(elem, &min, &max); qDebug(" pvolume %ld/%ld\n", min , max); snd_mixer_selem_set_playback_volume_all(elem, (a_percent * (max-min))/100); }

if (snd_mixer_selem_has_capture_switch(elem)) { snd_mixer_selem_set_capture_switch_all(elem, 1); // unmute all } if (snd_mixer_selem_has_capture_volume(elem)) { long min, max; snd_mixer_selem_get_capture_volume_range(elem, &min, &max); qDebug(" pvolume %ld/%ld\n", min , max); snd_mixer_selem_set_capture_volume_all(elem, (a_percent * (max-min))/100); //set capture volume for all } } snd_mixer_close(handle); return; }

int main(int argc, char *argv[]) { snd_pcm_t *m_pcm_handle;

int err,count; // Open connection to the PCM devic if ((err = snd_pcm_open(&m_pcm_handle, "plughw:1,0", SND_PCM_STREAM_CAPTURE, 0)) < 0) { for (count=0; count < 5 && err == -EBUSY; count++) { sleep(1); qDebug("AlsaStream:%d open error: %s (%d)\n ", __LINE__, snd_strerror(err), err); err = snd_pcm_open(&m_pcm_handle, "plughw:1,0", SND_PCM_STREAM_CAPTURE, 0); }

if (err < 0) { qDebug("AlsaStream:%d open error: %s (%d)\n ", __LINE__, snd_strerror(err), err); return; } if (err>= 0) { printf("Success\n"); } } set_default_volume("hw:1", 20); snd_pcm_close(m_pcm_handle); return 0; }