[pulseaudio-commits] [SCM] PulseAudio Sound Server branch, master, updated. v0.9.19-556-gf97faae

[Colin Guthrie]

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The master branch has been updated
      from  d30d22dfb8640431405b3d0f15455b29e817c167 (commit)

- Log -----------------------------------------------------------------
f97faae alsa: Set the rewind safeguard proportionally to sample spec
-----------------------------------------------------------------------

Summary of changes:
 src/modules/alsa/alsa-sink.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

-----------------------------------------------------------------------

commit f97faae006c0acbcd33056008196f3651fe5b0d3
Author: Colin Guthrie <cguthrie at mandriva.org>
Date:   Sat Sep 4 11:58:05 2010 +0100

    alsa: Set the rewind safeguard proportionally to sample spec
    
    Currently when rewinding alsa, a fixed value of 256 bytes is used,
    which represents 1.33ms @ 48kHz (2ch, 16bit). This is typically fine
    and due to DMA constraints we would not want to rewind less than this.
    
    However with more demanding sample specs, (e.g. 8ch 192kHz 32bit)
    256 bytes is likely not sufficient, so calculate what 1.33ms would
    be and use which ever value is bigger.
    
    Discussed with David Henningsson and Pierre-Louis Bossart here:
     http://thread.gmane.org/gmane.comp.audio.pulseaudio.general/7286

diff --git a/src/modules/alsa/alsa-sink.c b/src/modules/alsa/alsa-sink.c
index e92c6e5..e62dcc0 100644
--- a/src/modules/alsa/alsa-sink.c
+++ b/src/modules/alsa/alsa-sink.c
@@ -86,7 +86,8 @@
 
 #define VOLUME_ACCURACY (PA_VOLUME_NORM/100)  /* don't require volume adjustments to be perfectly correct. don't necessarily extend granularity in software unless the differences get greater than this level */
 
-#define DEFAULT_REWIND_SAFEGUARD_BYTES (256) /* 1.33ms @48kHz, should work for most hardware */
+#define DEFAULT_REWIND_SAFEGUARD_BYTES (256U) /* 1.33ms @48kHz, we'll never rewind less than this */
+#define DEFAULT_REWIND_SAFEGUARD_USEC (1330) /* 1.33ms, depending on channels/rate/sample we may rewind more than 256 above */
 
 struct userdata {
     pa_core *core;
@@ -1740,7 +1741,7 @@ pa_sink *pa_alsa_sink_new(pa_module *m, pa_modargs *ma, const char*driver, pa_ca
         goto fail;
     }
 
-    rewind_safeguard = DEFAULT_REWIND_SAFEGUARD_BYTES;
+    rewind_safeguard = PA_MAX(DEFAULT_REWIND_SAFEGUARD_BYTES, pa_usec_to_bytes(DEFAULT_REWIND_SAFEGUARD_USEC, &ss));
     if (pa_modargs_get_value_u32(ma, "rewind_safeguard", &rewind_safeguard) < 0) {
         pa_log("Failed to parse rewind_safeguard argument");
         goto fail;

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