libavresample: add mix level normalization option

Provides an option to disable mix level normalization

Signed-off-by: Diego Biurrun <diego@biurrun.de>

libavresample/audio_mix.c

@@ -335,7 +335,9 @@ int ff_audio_mix_init(AVAudioResampleContext *avr)
                                       avr->out_channel_layout,
                                       avr->center_mix_level,
                                       avr->surround_mix_level,
-                                      avr->lfe_mix_level, 1, matrix_dbl,
+                                      avr->lfe_mix_level,
+                                      avr->normalize_mix_level,
+                                      matrix_dbl,
                                       avr->in_channels,
                                       avr->matrix_encoding);
         if (ret < 0) {

libavresample/internal.h

@@ -45,6 +45,7 @@ struct AVAudioResampleContext {
     double center_mix_level;                    /**< center mix level       */
     double surround_mix_level;                  /**< surround mix level     */
     double lfe_mix_level;                       /**< lfe mix level          */
+    int normalize_mix_level;                    /**< enable mix level normalization */
     int force_resampling;                       /**< force resampling       */
     int filter_size;                            /**< length of each FIR filter in the resampling filterbank relative to the cutoff frequency */
     int phase_shift;                            /**< log2 of the number of entries in the resampling polyphase filterbank */

libavresample/options.c

@@ -47,6 +47,7 @@ static const AVOption options[] = {
     { "center_mix_level",       "Center Mix Level",         OFFSET(center_mix_level),       AV_OPT_TYPE_DOUBLE, { M_SQRT1_2             }, -32.0,                32.0,                   PARAM },
     { "surround_mix_level",     "Surround Mix Level",       OFFSET(surround_mix_level),     AV_OPT_TYPE_DOUBLE, { M_SQRT1_2             }, -32.0,                32.0,                   PARAM },
     { "lfe_mix_level",          "LFE Mix Level",            OFFSET(lfe_mix_level),          AV_OPT_TYPE_DOUBLE, { 0.0                   }, -32.0,                32.0,                   PARAM },
+    { "normalize_mix_level",    "Normalize Mix Level",      OFFSET(normalize_mix_level),    AV_OPT_TYPE_INT,    { 1                     }, 0,                    1,                      PARAM },
     { "force_resampling",       "Force Resampling",         OFFSET(force_resampling),       AV_OPT_TYPE_INT,    { 0                     }, 0,                    1,                      PARAM },
     { "filter_size",            "Resampling Filter Size",   OFFSET(filter_size),            AV_OPT_TYPE_INT,    { 16                    }, 0,                    32, /* ??? */           PARAM },
     { "phase_shift",            "Resampling Phase Shift",   OFFSET(phase_shift),            AV_OPT_TYPE_INT,    { 10                    }, 0,                    30, /* ??? */           PARAM },