[pulseaudio-discuss] [PATCH] optimization: Take samples from silence cache rather than write zeros.

[Jyri Sarha]

If the only stream to render from is muted take samples from the
silence cache. This should shrink memory/cache bandwidth. Again the
gain was not what I hoped for.
---
 src/pulsecore/sink.c |   32 ++++++++++++++++++++++----------
 1 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/src/pulsecore/sink.c b/src/pulsecore/sink.c
index d3a6dc9..6cda8c8 100644
--- a/src/pulsecore/sink.c
+++ b/src/pulsecore/sink.c
@@ -788,11 +788,17 @@ void pa_sink_render(pa_sink*s, size_t length, pa_memchunk *result) {
         pa_sw_cvolume_multiply(&volume, &s->thread_info.soft_volume, &info[0].volume);
 
         if (s->thread_info.soft_muted || !pa_cvolume_is_norm(&volume)) {
-            pa_memchunk_make_writable(result, 0);
-            if (s->thread_info.soft_muted || pa_cvolume_is_muted(&volume))
-                pa_silence_memchunk(result, &s->sample_spec);
-            else
+            if (s->thread_info.soft_muted || pa_cvolume_is_muted(&volume)) {
+                pa_memblock_unref(result->memblock);
+                pa_silence_memchunk_get(&s->core->silence_cache,
+                                        s->core->mempool,
+                                        result, 
+                                        &s->sample_spec, 
+                                        result->length);                
+            } else {
+                pa_memchunk_make_writable(result, 0);
                 pa_volume_memchunk(result, &s->sample_spec, &volume);
+            }
         }
     } else {
         void *ptr;
@@ -969,13 +975,19 @@ void pa_sink_render_full(pa_sink *s, size_t length, pa_memchunk *result) {
 
 	pa_sw_cvolume_multiply(&volume, &s->thread_info.soft_volume, &info[0].volume);
 	
-	if (s->thread_info.soft_muted || !pa_cvolume_is_norm(&volume)) {
-            pa_memchunk_make_writable(result, length);
-            if (s->thread_info.soft_muted || pa_cvolume_is_muted(&volume))
-                pa_silence_memchunk(result, &s->sample_spec);
-            else
+        if (s->thread_info.soft_muted || !pa_cvolume_is_norm(&volume)) {
+            if (s->thread_info.soft_muted || pa_cvolume_is_muted(&volume)) {
+                pa_memblock_unref(result->memblock);
+                pa_silence_memchunk_get(&s->core->silence_cache,
+                                        s->core->mempool,
+                                        result, 
+                                        &s->sample_spec, 
+                                        result->length);                
+            } else {
+                pa_memchunk_make_writable(result, length);
                 pa_volume_memchunk(result, &s->sample_spec, &volume);
-	}
+            }
+        }
     } else {
         void *ptr;
 
-- 
1.5.6.3