From a5c634935891ed8a45603bfa676d053d3e6a8a04 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Sat, 9 Jun 2012 02:06:58 +0200
Subject: [PATCH] swr: skip memset(0) in rematrix when the array is known to be
 already 0

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
---
 libswresample/rematrix.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libswresample/rematrix.c b/libswresample/rematrix.c
index 96246275b2..5fa77ce5f9 100644
--- a/libswresample/rematrix.c
+++ b/libswresample/rematrix.c
@@ -362,7 +362,8 @@ int swri_rematrix(SwrContext *s, AudioData *out, AudioData *in, int len, int mus
     for(out_i=0; out_i<out->ch_count; out_i++){
         switch(s->matrix_ch[out_i][0]){
         case 0:
-            memset(out->ch[out_i], 0, len * av_get_bytes_per_sample(s->int_sample_fmt));
+            if(mustcopy)
+                memset(out->ch[out_i], 0, len * av_get_bytes_per_sample(s->int_sample_fmt));
             break;
         case 1:
             in_i= s->matrix_ch[out_i][1];