142 lines
3.3 KiB
C++
142 lines
3.3 KiB
C++
#include "oslib/audiobackend_alsa.h"
|
|
#if USE_ALSA
|
|
#include <alsa/asoundlib.h>
|
|
|
|
snd_pcm_t *handle;
|
|
|
|
// We're making these functions static - there's no need to pollute the global namespace
|
|
static void alsa_init()
|
|
{
|
|
|
|
long loops;
|
|
int size;
|
|
|
|
snd_pcm_hw_params_t *params;
|
|
unsigned int val;
|
|
int dir=-1;
|
|
snd_pcm_uframes_t frames;
|
|
|
|
/* Open PCM device for playback. */
|
|
int rc = snd_pcm_open(&handle, "default", SND_PCM_STREAM_PLAYBACK, 0);
|
|
|
|
if (rc<0)
|
|
rc = snd_pcm_open(&handle, "plughw:0,0,0", SND_PCM_STREAM_PLAYBACK, 0);
|
|
|
|
if (rc<0)
|
|
rc = snd_pcm_open(&handle, "plughw:0,0", SND_PCM_STREAM_PLAYBACK, 0);
|
|
|
|
if (rc < 0)
|
|
{
|
|
fprintf(stderr, "unable to open PCM device: %s\n", snd_strerror(rc));
|
|
return;
|
|
}
|
|
|
|
/* Allocate a hardware parameters object. */
|
|
snd_pcm_hw_params_alloca(¶ms);
|
|
|
|
/* Fill it in with default values. */
|
|
rc=snd_pcm_hw_params_any(handle, params);
|
|
if (rc < 0)
|
|
{
|
|
fprintf(stderr, "Error:snd_pcm_hw_params_any %s\n", snd_strerror(rc));
|
|
return;
|
|
}
|
|
|
|
/* Set the desired hardware parameters. */
|
|
|
|
/* Interleaved mode */
|
|
rc=snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);
|
|
if (rc < 0)
|
|
{
|
|
fprintf(stderr, "Error:snd_pcm_hw_params_set_access %s\n", snd_strerror(rc));
|
|
return;
|
|
}
|
|
|
|
/* Signed 16-bit little-endian format */
|
|
rc=snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_LE);
|
|
if (rc < 0)
|
|
{
|
|
fprintf(stderr, "Error:snd_pcm_hw_params_set_format %s\n", snd_strerror(rc));
|
|
return;
|
|
}
|
|
|
|
/* Two channels (stereo) */
|
|
rc=snd_pcm_hw_params_set_channels(handle, params, 2);
|
|
if (rc < 0)
|
|
{
|
|
fprintf(stderr, "Error:snd_pcm_hw_params_set_channels %s\n", snd_strerror(rc));
|
|
return;
|
|
}
|
|
|
|
/* 44100 bits/second sampling rate (CD quality) */
|
|
val = 44100;
|
|
rc=snd_pcm_hw_params_set_rate_near(handle, params, &val, &dir);
|
|
if (rc < 0)
|
|
{
|
|
fprintf(stderr, "Error:snd_pcm_hw_params_set_rate_near %s\n", snd_strerror(rc));
|
|
return;
|
|
}
|
|
|
|
/* Set period size to settings.aica.BufferSize frames. */
|
|
frames = 2 * 1024;//settings.aica.BufferSize;
|
|
rc=snd_pcm_hw_params_set_period_size_near(handle, params, &frames, &dir);
|
|
if (rc < 0)
|
|
{
|
|
fprintf(stderr, "Error:snd_pcm_hw_params_set_buffer_size_near %s\n", snd_strerror(rc));
|
|
return;
|
|
}
|
|
frames*=4;
|
|
rc=snd_pcm_hw_params_set_buffer_size_near(handle, params, &frames);
|
|
if (rc < 0)
|
|
{
|
|
fprintf(stderr, "Error:snd_pcm_hw_params_set_buffer_size_near %s\n", snd_strerror(rc));
|
|
return;
|
|
}
|
|
|
|
/* Write the parameters to the driver */
|
|
rc = snd_pcm_hw_params(handle, params);
|
|
if (rc < 0)
|
|
{
|
|
fprintf(stderr, "Unable to set hw parameters: %s\n", snd_strerror(rc));
|
|
return;
|
|
}
|
|
}
|
|
|
|
static u32 alsa_push(void* frame, u32 samples, bool wait)
|
|
{
|
|
snd_pcm_nonblock(handle, wait ? 0 : 1);
|
|
|
|
int rc = snd_pcm_writei(handle, frame, samples);
|
|
if (rc == -EPIPE)
|
|
{
|
|
/* EPIPE means underrun */
|
|
fprintf(stderr, "ALSA: underrun occurred\n");
|
|
snd_pcm_prepare(handle);
|
|
alsa_push(frame, samples * 8, wait);
|
|
}
|
|
else if (rc < 0)
|
|
{
|
|
fprintf(stderr, "ALSA: error from writei: %s\n", snd_strerror(rc));
|
|
}
|
|
else if (rc != samples)
|
|
{
|
|
fprintf(stderr, "ALSA: short write, wrote %d frames of %d\n", rc, samples);
|
|
}
|
|
return 1;
|
|
}
|
|
|
|
static void alsa_term()
|
|
{
|
|
snd_pcm_drain(handle);
|
|
snd_pcm_close(handle);
|
|
}
|
|
|
|
audiobackend_t audiobackend_alsa = {
|
|
"alsa", // Slug
|
|
"Advanced Linux Sound Architecture", // Name
|
|
&alsa_init,
|
|
&alsa_push,
|
|
&alsa_term
|
|
};
|
|
#endif
|