rematrix: add parameter to tune volume

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswresample/rematrix.c

@@ -210,6 +210,9 @@ int swr_rematrix_init(SwrContext *s){
         if(s->out_ch_layout & (1ULL<<i))
             out_i++;
     }
+    if(s->rematrix_volume  < 0)
+        maxcoef = -s->rematrix_volume;
+
     if((   s->out_sample_fmt < AV_SAMPLE_FMT_FLT
         || s->int_sample_fmt < AV_SAMPLE_FMT_FLT) && maxcoef > 1.0){
         for(i=0; i<SWR_CH_MAX; i++)
@@ -218,6 +221,15 @@ int swr_rematrix_init(SwrContext *s){
                 s->matrix32[i][j]= lrintf(s->matrix[i][j] * 32768);
             }
     }
+
+    if(s->rematrix_volume > 0){
+        for(i=0; i<SWR_CH_MAX; i++)
+            for(j=0; j<SWR_CH_MAX; j++){
+                s->matrix[i][j] *= s->rematrix_volume;
+                s->matrix32[i][j]= lrintf(s->matrix[i][j] * 32768);
+            }
+    }
+
     for(i=0; i<av_get_channel_layout_nb_channels(s->out_ch_layout); i++){
         for(j=0; j<av_get_channel_layout_nb_channels(s->in_ch_layout); j++){
             av_log(NULL, AV_LOG_DEBUG, "%f ", s->matrix[i][j]);

libswresample/swresample.c

@@ -49,6 +49,7 @@ static const AVOption options[]={
 {"ocl",  "output channel layout", OFFSET(out_ch_layout), AV_OPT_TYPE_INT64, {.dbl=0}, 0, INT64_MAX, 0, "channel_layout"},
 {"clev", "center mix level"     , OFFSET(clev)         , AV_OPT_TYPE_FLOAT, {.dbl=C_30DB}, 0, 4, 0},
 {"slev", "sourround mix level"  , OFFSET(slev)         , AV_OPT_TYPE_FLOAT, {.dbl=C_30DB}, 0, 4, 0},
+{"rmvol", "rematrix volume"     , OFFSET(rematrix_volume), AV_OPT_TYPE_FLOAT, {.dbl=1.0}, -1000, 1000, 0},
 {"flags", NULL                  , OFFSET(flags)        , AV_OPT_TYPE_FLAGS, {.dbl=0}, 0,  UINT_MAX, 0, "flags"},
 {"res", "force resampling", 0, AV_OPT_TYPE_CONST, {.dbl=SWR_FLAG_RESAMPLE}, INT_MIN, INT_MAX, 0, "flags"},
 
@@ -176,7 +177,7 @@ int swr_init(SwrContext *s){
     if(!s->out_ch_layout)
         s->out_ch_layout= av_get_default_channel_layout(s->out.ch_count);
 
-    s->rematrix= s->out_ch_layout  !=s->in_ch_layout;
+    s->rematrix= s->out_ch_layout  !=s->in_ch_layout || s->rematrix_volume!=1.0;
 
 #define RSC 1 //FIXME finetune
     if(!s-> in.ch_count)

libswresample/swresample_internal.h

@@ -44,7 +44,7 @@ typedef struct SwrContext {          //FIXME find unused fields
     int      in_sample_rate;
     int     out_sample_rate;
     int flags;
-    float slev, clev;
+    float slev, clev, rematrix_volume;
 
     //below are private
     int int_bps;