Skip to content

Commit

Permalink
Fixed bug #79
Browse files Browse the repository at this point in the history 
Implemented snd_pcm_sw_params_set_start_threshold() and snd_pcm_sw_params_set_avail_min() in the ALSA 0.9 driver.
This doesn't actually change any latency for me, but it's the right thing to do...
  • Loading branch information
@slouken
slouken committed Mar 19, 2006
1 parent 4272881 commit 402337c
Showing 1 changed file with 68 additions and 12 deletions.
80 changes: 68 additions & 12 deletions src/audio/alsa/SDL_alsa_audio.c
View file
Expand Up @@ -69,6 +69,7 @@ static int (*SDL_NAME(snd_pcm_prepare))(snd_pcm_t *pcm);
static int (*SDL_NAME(snd_pcm_drain))(snd_pcm_t *pcm);
static const char *(*SDL_NAME(snd_strerror))(int errnum);
static size_t (*SDL_NAME(snd_pcm_hw_params_sizeof))(void);
static size_t (*SDL_NAME(snd_pcm_sw_params_sizeof))(void);
static int (*SDL_NAME(snd_pcm_hw_params_any))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params);
static int (*SDL_NAME(snd_pcm_hw_params_set_access))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_access_t access);
static int (*SDL_NAME(snd_pcm_hw_params_set_format))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, snd_pcm_format_t val);
Expand All @@ -79,7 +80,16 @@ static snd_pcm_uframes_t (*SDL_NAME(snd_pcm_hw_params_set_period_size_near))(snd
static unsigned int (*SDL_NAME(snd_pcm_hw_params_set_periods_near))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params, unsigned int val, int *dir);
static int (*SDL_NAME(snd_pcm_hw_params))(snd_pcm_t *pcm, snd_pcm_hw_params_t *params);
static int (*SDL_NAME(snd_pcm_nonblock))(snd_pcm_t *pcm, int nonblock);
/*
static unsigned int (*SDL_NAME(snd_pcm_hw_params_get_period_size))(const snd_pcm_hw_params_t *params);
static int (*SDL_NAME(snd_pcm_hw_params_get_periods))(snd_pcm_hw_params_t *params);
*/
static int (*SDL_NAME(snd_pcm_sw_params_current))(snd_pcm_t *pcm, snd_pcm_sw_params_t *swparams);
static int (*SDL_NAME(snd_pcm_sw_params_set_start_threshold))(snd_pcm_t *pcm, snd_pcm_sw_params_t *params, snd_pcm_uframes_t val);
static int (*SDL_NAME(snd_pcm_sw_params_set_avail_min))(snd_pcm_t *pcm, snd_pcm_sw_params_t *params, snd_pcm_uframes_t val);
static int (*SDL_NAME(snd_pcm_sw_params))(snd_pcm_t *pcm, snd_pcm_sw_params_t *params);
#define snd_pcm_hw_params_sizeof SDL_NAME(snd_pcm_hw_params_sizeof)
#define snd_pcm_sw_params_sizeof SDL_NAME(snd_pcm_sw_params_sizeof)

/* cast funcs to char* first, to please GCC's strict aliasing rules. */
static struct {
Expand All @@ -94,6 +104,7 @@ static struct {
{ "snd_pcm_drain", (void**)(char*)&SDL_NAME(snd_pcm_drain) },
{ "snd_strerror", (void**)(char*)&SDL_NAME(snd_strerror) },
{ "snd_pcm_hw_params_sizeof", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_sizeof) },
{ "snd_pcm_sw_params_sizeof", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_sizeof) },
{ "snd_pcm_hw_params_any", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_any) },
{ "snd_pcm_hw_params_set_access", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_access) },
{ "snd_pcm_hw_params_set_format", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_format) },
Expand All @@ -104,6 +115,14 @@ static struct {
{ "snd_pcm_hw_params_set_periods_near", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_set_periods_near) },
{ "snd_pcm_hw_params", (void**)(char*)&SDL_NAME(snd_pcm_hw_params) },
{ "snd_pcm_nonblock", (void**)(char*)&SDL_NAME(snd_pcm_nonblock) },
/*
{ "snd_pcm_hw_params_get_period_size", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_period_size) },
{ "snd_pcm_hw_params_get_periods", (void**)(char*)&SDL_NAME(snd_pcm_hw_params_get_periods) },
*/
{ "snd_pcm_sw_params_current", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_current) },
{ "snd_pcm_sw_params_set_start_threshold", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_set_start_threshold) },
{ "snd_pcm_sw_params_set_avail_min", (void**)(char*)&SDL_NAME(snd_pcm_sw_params_set_avail_min) },
{ "snd_pcm_sw_params", (void**)(char*)&SDL_NAME(snd_pcm_sw_params) },
};

static void UnloadALSALibrary(void) {
Expand Down Expand Up @@ -304,7 +323,8 @@ static void ALSA_CloseAudio(_THIS)
static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec)
{
int status;
snd_pcm_hw_params_t *params;
snd_pcm_hw_params_t *hwparams;
snd_pcm_sw_params_t *swparams;
snd_pcm_format_t format;
snd_pcm_uframes_t frames;
Uint16 test_format;
Expand All @@ -319,16 +339,16 @@ static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec)
}

/* Figure out what the hardware is capable of */
snd_pcm_hw_params_alloca(&params);
status = SDL_NAME(snd_pcm_hw_params_any)(pcm_handle, params);
snd_pcm_hw_params_alloca(&hwparams);
status = SDL_NAME(snd_pcm_hw_params_any)(pcm_handle, hwparams);
if ( status < 0 ) {
SDL_SetError("Couldn't get hardware config: %s", SDL_NAME(snd_strerror)(status));
ALSA_CloseAudio(this);
return(-1);
}

/* SDL only uses interleaved sample output */
status = SDL_NAME(snd_pcm_hw_params_set_access)(pcm_handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);
status = SDL_NAME(snd_pcm_hw_params_set_access)(pcm_handle, hwparams, SND_PCM_ACCESS_RW_INTERLEAVED);
if ( status < 0 ) {
SDL_SetError("Couldn't set interleaved access: %s", SDL_NAME(snd_strerror)(status));
ALSA_CloseAudio(this);
Expand Down Expand Up @@ -363,7 +383,7 @@ static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec)
break;
}
if ( format != 0 ) {
status = SDL_NAME(snd_pcm_hw_params_set_format)(pcm_handle, params, format);
status = SDL_NAME(snd_pcm_hw_params_set_format)(pcm_handle, hwparams, format);
}
if ( status < 0 ) {
test_format = SDL_NextAudioFormat();
Expand All @@ -377,9 +397,9 @@ static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec)
spec->format = test_format;

/* Set the number of channels */
status = SDL_NAME(snd_pcm_hw_params_set_channels)(pcm_handle, params, spec->channels);
status = SDL_NAME(snd_pcm_hw_params_set_channels)(pcm_handle, hwparams, spec->channels);
if ( status < 0 ) {
status = SDL_NAME(snd_pcm_hw_params_get_channels)(params);
status = SDL_NAME(snd_pcm_hw_params_get_channels)(hwparams);
if ( (status <= 0) || (status > 2) ) {
SDL_SetError("Couldn't set audio channels");
ALSA_CloseAudio(this);
Expand All @@ -389,7 +409,7 @@ static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec)
}

/* Set the audio rate */
status = SDL_NAME(snd_pcm_hw_params_set_rate_near)(pcm_handle, params, spec->freq, NULL);
status = SDL_NAME(snd_pcm_hw_params_set_rate_near)(pcm_handle, hwparams, spec->freq, NULL);
if ( status < 0 ) {
SDL_SetError("Couldn't set audio frequency: %s", SDL_NAME(snd_strerror)(status));
ALSA_CloseAudio(this);
Expand All @@ -399,14 +419,50 @@ static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec)

/* Set the buffer size, in samples */
frames = spec->samples;
frames = SDL_NAME(snd_pcm_hw_params_set_period_size_near)(pcm_handle, params, frames, NULL);
frames = SDL_NAME(snd_pcm_hw_params_set_period_size_near)(pcm_handle, hwparams, frames, NULL);
spec->samples = frames;
SDL_NAME(snd_pcm_hw_params_set_periods_near)(pcm_handle, params, 2, NULL);
SDL_NAME(snd_pcm_hw_params_set_periods_near)(pcm_handle, hwparams, 2, NULL);

/* "set" the hardware with the desired parameters */
status = SDL_NAME(snd_pcm_hw_params)(pcm_handle, params);
status = SDL_NAME(snd_pcm_hw_params)(pcm_handle, hwparams);
if ( status < 0 ) {
SDL_SetError("Couldn't set hardware audio parameters: %s", SDL_NAME(snd_strerror)(status));
ALSA_CloseAudio(this);
return(-1);
}

/*
{ unsigned int bufsize; int fragments;
bufsize = SDL_NAME(snd_pcm_hw_params_get_period_size)(hwparams);
fragments = SDL_NAME(snd_pcm_hw_params_get_periods)(hwparams);
fprintf(stderr, "ALSA: bufsize = %ld, fragments = %d\n", bufsize, fragments);
}
*/

/* Set the software parameters */
snd_pcm_sw_params_alloca(&swparams);
status = SDL_NAME(snd_pcm_sw_params_current)(pcm_handle, swparams);
if ( status < 0 ) {
SDL_SetError("Couldn't get software config: %s", SDL_NAME(snd_strerror)(status));
ALSA_CloseAudio(this);
return(-1);
}
status = SDL_NAME(snd_pcm_sw_params_set_start_threshold)(pcm_handle, swparams, 0);
if ( status < 0 ) {
SDL_SetError("Couldn't set start threshold: %s", SDL_NAME(snd_strerror)(status));
ALSA_CloseAudio(this);
return(-1);
}
status = SDL_NAME(snd_pcm_sw_params_set_avail_min)(pcm_handle, swparams, frames);
if ( status < 0 ) {
SDL_SetError("Couldn't set avail min: %s", SDL_NAME(snd_strerror)(status));
ALSA_CloseAudio(this);
return(-1);
}
status = SDL_NAME(snd_pcm_sw_params)(pcm_handle, swparams);
if ( status < 0 ) {
SDL_SetError("Couldn't set audio parameters: %s", SDL_NAME(snd_strerror)(status));
SDL_SetError("Couldn't set software audio parameters: %s", SDL_NAME(snd_strerror)(status));
ALSA_CloseAudio(this);
return(-1);
}
Expand Down

0 comments on commit 402337c

Please sign in to comment.