Merge commit 'a49aa440'

* commit 'a49aa440':
  af_volume: implement replaygain pre-amplification

Conflicts:
	doc/filters.texi
Merged-by: Michael Niedermayer <michaelni@gmx.at>

doc/filters.texi

@@ -1847,6 +1847,11 @@ Prefer track gain, if present.
 Prefer album gain, if present.
 @end table
 
+@item replaygain_preamp
+Pre-amplification gain in dB to apply to the selected replaygain gain.
+
+Default value for @var{replaygain_preamp} is 0.0.
+
 @item eval
 Set when the volume expression is evaluated.
 

libavfilter/af_volume.c

@@ -79,6 +79,8 @@ static const AVOption volume_options[] = {
         { "ignore", "replaygain side data is ignored", 0, AV_OPT_TYPE_CONST, { .i64 = REPLAYGAIN_IGNORE }, 0, 0, A, "replaygain" },
         { "track",  "track gain is preferred",         0, AV_OPT_TYPE_CONST, { .i64 = REPLAYGAIN_TRACK  }, 0, 0, A, "replaygain" },
         { "album",  "album gain is preferred",         0, AV_OPT_TYPE_CONST, { .i64 = REPLAYGAIN_ALBUM  }, 0, 0, A, "replaygain" },
+    { "replaygain_preamp", "Apply replaygain pre-amplification",
+            OFFSET(replaygain_preamp), AV_OPT_TYPE_DOUBLE, { .dbl = 0.0 }, -15.0, 15.0, A },
     { NULL },
 };
 
@@ -358,7 +360,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
             av_log(inlink->dst, AV_LOG_VERBOSE,
                    "Using gain %f dB from replaygain side data.\n", g);
 
-            vol->volume   = pow(10, g / 20);
+            vol->volume   = pow(10, (g + vol->replaygain_preamp) / 20);
             vol->volume_i = (int)(vol->volume * 256 + 0.5);
 
             volume_init(vol);

libavfilter/af_volume.h

@@ -75,6 +75,7 @@ typedef struct VolumeContext {
     double var_values[VAR_VARS_NB];
 
     enum ReplayGainType replaygain;
+    double replaygain_preamp;
     double volume;
     int    volume_i;
     int    channels;