Specify the buffer size to ALSA, so the period count remains flexible

Under conditions where the period size is fixed (such as dmix), ALSA will still
attempt to provide the requested number of periods even if the requested period
size needs to be dramatically altered. In these cases, it would be better to
increase or decrease the period count, instead of growing or shrinking the
total buffer size and significantly changing the latency.

1 files changed, 5 insertions, 3 deletions

diff --git a/Alc/alsa.c b/Alc/alsa.c
index b0b35305..b56d0537 100644
--- a/Alc/alsa.c
+++ b/Alc/alsa.c
@@ -510,6 +510,7 @@ static ALCboolean alsa_reset_playback(ALCdevice *device)
 {
     alsa_data *data = (alsa_data*)device->ExtraData;
     snd_pcm_uframes_t periodSizeInFrames;
+    snd_pcm_uframes_t bufferSizeInFrames;
     snd_pcm_sw_params_t *sp = NULL;
     snd_pcm_hw_params_t *p = NULL;
     snd_pcm_access_t access;
@@ -614,12 +615,13 @@ static ALCboolean alsa_reset_playback(ALCdevice *device)
                 err = "set channels";
         }
     }
-    /* set periods (implicitly constrains period/buffer parameters) */
-    if(i >= 0 && (i=psnd_pcm_hw_params_set_periods_near(data->pcmHandle, p, &periods, NULL)) < 0)
-        err = "set periods near";
     /* set rate (implicitly constrains period/buffer parameters) */
     if(i >= 0 && (i=psnd_pcm_hw_params_set_rate_near(data->pcmHandle, p, &rate, NULL)) < 0)
         err = "set rate near";
+    /* set buffer size (implicitly constrains period/buffer parameters) */
+    bufferSizeInFrames = periodSizeInFrames * periods;
+    if(i >= 0 && (i=psnd_pcm_hw_params_set_buffer_size_near(data->pcmHandle, p, &bufferSizeInFrames)) < 0)
+        err = "set buffer size near";
     /* set period size in frame units (implicitly sets buffer size/bytes/time and period time/bytes) */
     if(i >= 0 && (i=psnd_pcm_hw_params_set_period_size_near(data->pcmHandle, p, &periodSizeInFrames, NULL)) < 0)
         err = "set period size near";