Change ALSA output period size to 2048 samples.

Anything less seemingly triggers a bug in the ALSA PulseAudio
plugin when used against PipeWire (audio just never starts playing).

It would be nice to generally have less latency here, but with the
current design based on large resampling queues, this isn't going
to be what causes it.

diff --git a/nageru/alsa_output.cpp b/nageru/alsa_output.cpp
index bc2c89c761ea5a13817054ffb10b4fab7a594279..890081721948e2dd5f9465825aae19d99bab3bbe 100644 (file)
--- a/nageru/alsa_output.cpp
+++ b/nageru/alsa_output.cpp
@@ -34,12 +34,12 @@ ALSAOutput::ALSAOutput(int sample_rate, int num_channels)
        die_on_error("snd_pcm_hw_params_set_rate()", snd_pcm_hw_params_set_rate(pcm_handle, hw_params, sample_rate, 0));
        die_on_error("snd_pcm_hw_params_set_channels", snd_pcm_hw_params_set_channels(pcm_handle, hw_params, num_channels));
 
-       // Fragment size of 512 samples. (A frame at 60 fps/48 kHz is 800 samples.)
-       // We ask for 16 such periods (~170 ms buffer).
-       unsigned int num_periods = 16;
+       // Fragment size of 2048 samples. (A frame at 60 fps/48 kHz is 800 samples.)
+       // We ask for 4 such periods (~170 ms buffer).
+       unsigned int num_periods = 4;
        int dir = 0;
        die_on_error("snd_pcm_hw_params_set_periods_near()", snd_pcm_hw_params_set_periods_near(pcm_handle, hw_params, &num_periods, &dir));
-       period_size = 512;
+       period_size = 2048;
        dir = 0;
        die_on_error("snd_pcm_hw_params_set_period_size_near()", snd_pcm_hw_params_set_period_size_near(pcm_handle, hw_params, &period_size, &dir));
        die_on_error("snd_pcm_hw_params()", snd_pcm_hw_params(pcm_handle, hw_params));