alsa: fix option parsing and restore default period_time

Two bugs here led to a large number of interrupts being generated on the sound card when ALSA output is being used. Because we specify no default period_time, the sound card gives us 3000 interrupts/sec rather than a more sane 20 or 30. This completes the revert of dd7711 already started by 4ca24f. The larger bug was in the change to config_get_block_unsigned() and using 0 as the default value for both 'buffer_time' and 'period_time'. This means any pre-setting of these options in newAlsaData() gets wiped out. Add a new default for period_time, and ensure default values for buffer_time and period_time are used if none are provided by the user. Signed-off-by: Dan McGee <dan@archlinux.org> [mk: set defaults in newAlsaData() to fix auto-configuration; renamed "_MS" back to "_US" because ALSA expects microseconds, not milliseconds] Signed-off-by: Max Kellermann <max@duempel.org>

alsa: fix option parsing and restore default period_time
27baf691 · Dan McGee · Max Kellermann · 16796b12 · 27baf691
Commit 27baf691 authored Jan 25, 2009 by Dan McGee Committed by Max Kellermann Jan 25, 2009
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Showing with 6 additions and 3 deletions

alsa_plugin.c src/output/alsa_plugin.c +6 -3

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--- a/src/output/alsa_plugin.c
+++ b/src/output/alsa_plugin.c
@@ -32,6 +32,7 @@ static const char default_device[] = "default";

 enum {
 	MPD_ALSA_BUFFER_TIME_US = 500000,
+	MPD_ALSA_PERIOD_TIME_US = 125000,
 };

 #define MPD_ALSA_RETRY_NR 5
@@ -72,7 +73,7 @@ static AlsaData *newAlsaData(void)
 	ret->writei = snd_pcm_writei;
 	ret->useMmap = 0;
 	ret->buffer_time = MPD_ALSA_BUFFER_TIME_US;
-	ret->period_time = 0;
+	ret->period_time = MPD_ALSA_PERIOD_TIME_US;

 	//use alsa mixer by default
 	mixer_init(&ret->mixer, &alsa_mixer);
@@ -94,8 +95,10 @@ alsa_configure(AlsaData *ad, struct config_param *param)

 	ad->useMmap = config_get_block_bool(param, "use_mmap", false);

-	ad->buffer_time = config_get_block_unsigned(param, "buffer_time", 0);
-	ad->period_time = config_get_block_unsigned(param, "period_time", 0);
+	ad->buffer_time = config_get_block_unsigned(param, "buffer_time",
+			MPD_ALSA_BUFFER_TIME_US);
+	ad->period_time = config_get_block_unsigned(param, "period_time",
+			MPD_ALSA_PERIOD_TIME_US);

 #ifdef SND_PCM_NO_AUTO_RESAMPLE
 	if (!config_get_block_bool(param, "auto_resample", true))