Increase ALSA audio buffer

jyavenard · jyavenard · commit a1ff28e1b713 · 2010-12-14T00:52:17.000+11:00
Increase ALSA audio buffer requirement from 200ms to 400ms as playing TrueHD generated fair amount of buffer underruns on my machine
diff --git a/mythtv/libs/libmyth/audiooutputalsa.cpp b/mythtv/libs/libmyth/audiooutputalsa.cpp
@@ -238,7 +238,8 @@ bool AudioOutputALSA::IncPreallocBufferSize(int buffer_time)
         (buffer_time / 1000) *
         output_bytes_per_frame / 1024;
 
-    VBAUDIO(QString("Prealloc buffer cur: %1 max: %3").arg(cur).arg(max));
+    VBAUDIO(QString("Prealloc buffer cur: %1 need: %2 max: %3")
+            .arg(cur).arg(size).arg(max));
 
     if (size > max)
     {
@@ -401,7 +402,7 @@ bool AudioOutputALSA::OpenDevice()
     }
 
     period_time = 50000;  // aim for an interrupt every 50ms
-    buffer_time = period_time << 2; // buffer 200ms worth of samples
+    buffer_time = period_time << 3; // buffer 400ms worth of samples
 
     err = SetParameters(pcm_handle, format, channels, samplerate,
                         buffer_time, period_time);

Original file line number	Diff line number	Diff line change
`@@ -238,7 +238,8 @@ bool AudioOutputALSA::IncPreallocBufferSize(int buffer_time)`
`238`	`238`	`(buffer_time / 1000) *`
`239`	`239`	`output_bytes_per_frame / 1024;`
`240`	`240`
`241`		`- VBAUDIO(QString("Prealloc buffer cur: %1 max: %3").arg(cur).arg(max));`
	`241`	`+ VBAUDIO(QString("Prealloc buffer cur: %1 need: %2 max: %3")`
	`242`	`+ .arg(cur).arg(size).arg(max));`
`242`	`243`
`243`	`244`	`if (size > max)`
`244`	`245`	`{`
`@@ -401,7 +402,7 @@ bool AudioOutputALSA::OpenDevice()`
`401`	`402`	`}`
`402`	`403`
`403`	`404`	`period_time = 50000; // aim for an interrupt every 50ms`
`404`		`- buffer_time = period_time << 2; // buffer 200ms worth of samples`
	`405`	`+ buffer_time = period_time << 3; // buffer 400ms worth of samples`
`405`	`406`
`406`	`407`	`err = SetParameters(pcm_handle, format, channels, samplerate,`
`407`	`408`	`buffer_time, period_time);`