Author: reimar
Date: Sat Mar 25 19:10:41 2023
New Revision: 38413
Log:
ao_openal.c: Play stereo using the special stereo format.
This matches better the output expected in most cases,
where the left channel only plays on the left speaker,
instead of as a sound coming from the left but reaching
both ears at an offset.
Modified:
trunk/libao2/ao_openal.c
Modified: trunk/libao2/ao_openal.c
==============================================================================
--- trunk/libao2/ao_openal.c Tue Feb 21 00:41:00 2023 (r38412)
+++ trunk/libao2/ao_openal.c Sat Mar 25 19:10:41 2023 (r38413)
@@ -61,6 +61,7 @@ static ALuint sources[MAX_CHANS];
static int cur_buf[MAX_CHANS];
static int unqueue_buf[MAX_CHANS];
static int16_t *tmpbuf;
+static int num_sources;
static int control(int cmd, void *arg) {
@@ -126,15 +127,18 @@ static int init(int rate, int channels,
alcMakeContextCurrent(ctx);
alListenerfv(AL_POSITION, position);
alListenerfv(AL_ORIENTATION, direction);
- alGenSources(channels, sources);
- for (i = 0; i < channels; i++) {
+ // play stereo using a single source - this is closer
+ // to the result from other aos and what people expect.
+ num_sources = channels <= 2 ? 1 : channels;
+ alGenSources(num_sources, sources);
+ for (i = 0; i < num_sources; i++) {
cur_buf[i] = 0;
unqueue_buf[i] = 0;
alGenBuffers(NUM_BUF, buffers[i]);
alSourcefv(sources[i], AL_POSITION, sppos[i]);
alSource3f(sources[i], AL_VELOCITY, 0, 0, 0);
}
- if (channels == 1)
+ if (num_sources == 1)
alSource3f(sources[0], AL_POSITION, 0, 0, 1);
ao_data.channels = channels;
alcGetIntegerv(dev, ALC_FREQUENCY, 1, &freq);
@@ -174,7 +178,7 @@ static void uninit(int immed) {
static void unqueue_buffers(void) {
ALint p;
int s;
- for (s = 0; s < ao_data.channels; s++) {
+ for (s = 0; s < num_sources; s++) {
int till_wrap = NUM_BUF - unqueue_buf[s];
alGetSourcei(sources[s], AL_BUFFERS_PROCESSED, &p);
if (p >= till_wrap) {
@@ -193,7 +197,7 @@ static void unqueue_buffers(void) {
* \brief stop playing and empty buffers (for seeking/pause)
*/
static void reset(void) {
- alSourceStopv(ao_data.channels, sources);
+ alSourceStopv(num_sources, sources);
unqueue_buffers();
}
@@ -201,14 +205,14 @@ static void reset(void) {
* \brief stop playing, keep buffers (for pause)
*/
static void audio_pause(void) {
- alSourcePausev(ao_data.channels, sources);
+ alSourcePausev(num_sources, sources);
}
/**
* \brief resume playing, after audio_pause()
*/
static void audio_resume(void) {
- alSourcePlayv(ao_data.channels, sources);
+ alSourcePlayv(num_sources, sources);
}
static int get_space(void) {
@@ -217,7 +221,7 @@ static int get_space(void) {
alGetSourcei(sources[0], AL_BUFFERS_QUEUED, &queued);
queued = NUM_BUF - queued - 3;
if (queued < 0) return 0;
- return queued * CHUNK_SIZE * ao_data.channels;
+ return queued * CHUNK_SIZE * num_sources;
}
/**
@@ -228,22 +232,23 @@ static int play(void *data, int len, int
int i, j, k;
int ch;
int16_t *d = data;
- len /= ao_data.channels * CHUNK_SIZE;
+ int format = ao_data.channels == 2 && num_sources == 1 ? AL_FORMAT_STEREO16 : AL_FORMAT_MONO16;
+ len /= num_sources * CHUNK_SIZE;
for (i = 0; i < len; i++) {
- for (ch = 0; ch < ao_data.channels; ch++) {
- for (j = 0, k = ch; j < CHUNK_SIZE / 2; j++, k += ao_data.channels)
+ for (ch = 0; ch < num_sources; ch++) {
+ for (j = 0, k = ch; j < CHUNK_SIZE / 2; j++, k += num_sources)
tmpbuf[j] = d[k];
- alBufferData(buffers[ch][cur_buf[ch]], AL_FORMAT_MONO16, tmpbuf,
+ alBufferData(buffers[ch][cur_buf[ch]], format, tmpbuf,
CHUNK_SIZE, ao_data.samplerate);
alSourceQueueBuffers(sources[ch], 1, &buffers[ch][cur_buf[ch]]);
cur_buf[ch] = (cur_buf[ch] + 1) % NUM_BUF;
}
- d += ao_data.channels * CHUNK_SIZE / 2;
+ d += num_sources * CHUNK_SIZE / 2;
}
alGetSourcei(sources[0], AL_SOURCE_STATE, &state);
if (state != AL_PLAYING) // checked here in case of an underrun
- alSourcePlayv(ao_data.channels, sources);
- return len * ao_data.channels * CHUNK_SIZE;
+ alSourcePlayv(num_sources, sources);
+ return len * num_sources * CHUNK_SIZE;
}
static float get_delay(void) {
