X-Git-Url: https://git.sesse.net/?p=nageru;a=blobdiff_plain;f=alsa_output.cpp;h=7dd10244b094d83b9f93c65af0b8e87dc4e5a5c6;hp=52f4936924f7a84570b92aa168af9a79321a735d;hb=refs%2Fheads%2Fmultichannel_audio;hpb=194872611b21bb070f4dfcf5beda6c36d25459ea

diff --git a/alsa_output.cpp b/alsa_output.cpp
index 52f4936..7dd1024 100644
--- a/alsa_output.cpp
+++ b/alsa_output.cpp
@@ -1,5 +1,9 @@
 #include "alsa_output.h"
 
+#include <alsa/asoundlib.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
 #include <vector>
 
 using namespace std;
@@ -17,7 +21,7 @@ void die_on_error(const char *func_name, int err)
 }  // namespace
 
 ALSAOutput::ALSAOutput(int sample_rate, int num_channels)
-	: num_channels(num_channels)
+	: sample_rate(sample_rate), num_channels(num_channels)
 {
 	die_on_error("snd_pcm_open()", snd_pcm_open(&pcm_handle, "default", SND_PCM_STREAM_PLAYBACK, 0));
 
@@ -31,17 +35,24 @@ ALSAOutput::ALSAOutput(int sample_rate, int num_channels)
 	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 four such periods.
-	unsigned int num_periods = 4;
+	// We ask for 16 such periods (~170 ms buffer).
+	unsigned int num_periods = 16;
 	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));
+	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;
 	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));
+	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));
 	//snd_pcm_hw_params_free(hw_params);
 
+	snd_pcm_sw_params_t *sw_params;
+	snd_pcm_sw_params_alloca(&sw_params);
+	die_on_error("snd_pcm_sw_params_current()", snd_pcm_sw_params_current(pcm_handle, sw_params));
+	die_on_error("snd_pcm_sw_params_set_start_threshold", snd_pcm_sw_params_set_start_threshold(pcm_handle, sw_params, num_periods * period_size / 2));
+	die_on_error("snd_pcm_sw_params()", snd_pcm_sw_params(pcm_handle, sw_params));
+
 	die_on_error("snd_pcm_nonblock", snd_pcm_nonblock(pcm_handle, 1));
+	die_on_error("snd_pcm_prepare()", snd_pcm_prepare(pcm_handle));
 }
 
 void ALSAOutput::write(const vector<float> &samples)
@@ -72,7 +83,8 @@ try_again:
 		if (ret == 0) {
 			if (buffer.size() >= period_size * num_channels * 8) {
 				// OK, almost 100 ms. Giving up.
-				fprintf(stderr, "warning: ALSA overrun, dropping some audio\n");
+				fprintf(stderr, "warning: ALSA overrun, dropping some audio (%d ms)\n",
+					int(buffer.size() * 1000 / (num_channels * sample_rate)));
 				buffer.clear();
 			}
 		} else if (ret > 0) {