FS-7772: mod_opus: add functionality to keep FEC enabled on the encoder by modifying...

diff --git a/src/mod/codecs/mod_opus/mod_opus.c b/src/mod/codecs/mod_opus/mod_opus.c
index 4e71ca6f6e4c93a7aa01f0d5ad0b1ef327453971..9112b46282c23a1db7bd2dcfc819602ed6febef5 100644 (file)
--- a/src/mod/codecs/mod_opus/mod_opus.c
+++ b/src/mod/codecs/mod_opus/mod_opus.c
@@ -25,6 +25,7 @@
  *
  * Brian K. West <brian@freeswitch.org>
  * Noel Morgan <noel@vwci.com>
+ * Dragos Oancea <droancea@yahoo.com>
  *
  * mod_opus.c -- The OPUS ultra-low delay audio codec (http://www.opus-codec.org/)
  *
@@ -86,6 +87,7 @@ struct {
        int sprop_maxcapturerate;
        int plpct;
        int asymmetric_samplerates;
+       int keep_fec;
        int debuginfo;
     switch_mutex_t *mutex;
 } opus_prefs;
@@ -594,6 +596,8 @@ static switch_status_t opus_load_config(switch_bool_t reload)
                                opus_prefs.plpct = atoi(val);
                        } else if (!strcasecmp(key, "asymmetric-sample-rates")) {
                                opus_prefs.asymmetric_samplerates = atoi(val);
+                       } else if (!strcasecmp(key, "keep-fec-enabled")) {
+                               opus_prefs.keep_fec = atoi(val);
                        } else if (!strcasecmp(key, "maxaveragebitrate")) {
                                opus_prefs.maxaveragebitrate = atoi(val);
                                if ( opus_prefs.maxaveragebitrate < 6000 || opus_prefs.maxaveragebitrate > 510000 ) {
@@ -621,6 +625,55 @@ static switch_status_t opus_load_config(switch_bool_t reload)
     return status;
 }
 
+static switch_status_t switch_opus_keep_fec_enabled(switch_codec_t *codec)
+{
+       struct opus_context *context = codec->private_info;
+       opus_int32 current_bitrate;
+       opus_int32 current_loss;
+       uint32_t LBRR_threshold_bitrate,LBRR_rate_thres_bps,real_target_bitrate ;  
+       opus_int32 a32,b32; 
+       uint32_t fs = context->enc_frame_size * 1000 / (codec->implementation->microseconds_per_packet / 1000);
+       float frame_rate = 1000 / (codec->implementation->microseconds_per_packet / 1000);
+       uint32_t step = 8000 / (codec->implementation->microseconds_per_packet / 1000); /* this works for 10 ms, 20 ms and 40 ms frame sizes. not for 60 ms*/
+
+       opus_encoder_ctl(context->encoder_object, OPUS_GET_BITRATE(&current_bitrate));
+       opus_encoder_ctl(context->encoder_object, OPUS_GET_PACKET_LOSS_PERC(&current_loss));
+       if( fs == 8000 ) {
+               LBRR_rate_thres_bps = 12000; /*LBRR_NB_MIN_RATE_BPS*/
+       } else if( fs == 12000 ) {
+               LBRR_rate_thres_bps = 14000; /*LBRR_MB_MIN_RATE_BPS*/
+       } else { 
+               LBRR_rate_thres_bps = 16000; /*LBRR_WB_MIN_RATE_BPS*/
+       }
+       /*see opus-1.1/src/opus_encoder.c , opus_encode_native() */
+       real_target_bitrate =  8 * (current_bitrate * context->enc_frame_size / ( fs * 8 ) - 1) * frame_rate ;
+       /*check if the internally used bitrate is above the threshold defined in opus-1.1/silk/control_codec.c  */
+       a32 =  LBRR_rate_thres_bps * (125 -(((current_loss) < (25)) ? (current_loss) :  (25)));
+       b32 =  ((opus_int32)((0.01) * ((opus_int64)1 << (16)) + 0.5));
+       LBRR_threshold_bitrate =  (a32 >> 16) * (opus_int32)((opus_int16)b32) + (((a32 & 0x0000FFFF) * (opus_int32)((opus_int16)b32)) >> 16);
+       if ((!real_target_bitrate || !LBRR_threshold_bitrate)){
+               switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR,"Opus encoder: error while controlling FEC params\n");
+               return SWITCH_STATUS_FALSE;
+       }
+       /* Is there any FEC at the current bitrate and requested packet loss ? 
+        * If yes, then keep the current bitrate. If not, modify bitrate to keep FEC on. */
+       if (real_target_bitrate > LBRR_threshold_bitrate) {
+               /*FEC is already enabled, do nothing*/
+               if (globals.debug)
+                       switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_DEBUG,"Opus encoder: FEC is enabled\n");
+               return SWITCH_STATUS_SUCCESS;
+       } else {
+               while (real_target_bitrate <= LBRR_threshold_bitrate) {
+                       current_bitrate += step;
+                       real_target_bitrate =  8 * (current_bitrate * context->enc_frame_size / ( fs * 8 ) - 1) * frame_rate ;
+               }
+               opus_encoder_ctl(context->encoder_object,OPUS_SET_BITRATE(current_bitrate));
+               if (globals.debug)
+                       switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_DEBUG,"Opus encoder: increased bitrate to [%d] to keep FEC enabled\n",current_bitrate);
+               return SWITCH_STATUS_SUCCESS;
+       }
+}
+
 static switch_status_t switch_opus_control(switch_codec_t *codec,
                                                                                   switch_codec_control_command_t cmd,
                                                                                   switch_codec_control_type_t ctype,
@@ -645,6 +698,8 @@ static switch_status_t switch_opus_control(switch_codec_t *codec,
 
                        if (plpct != context->old_plpct) {
                                opus_encoder_ctl(context->encoder_object, OPUS_SET_PACKET_LOSS_PERC(plpct));
+                               if (opus_prefs.keep_fec)
+                                       switch_opus_keep_fec_enabled(codec);
                        }
                        context->old_plpct = plpct;
                }
@@ -805,7 +860,7 @@ SWITCH_MODULE_LOAD_FUNCTION(mod_opus_load)
                                                                                         switch_opus_encode,    /* function to encode raw data into encoded data */
                                                                                         switch_opus_decode,    /* function to decode encoded data into raw data */
                                                                                         switch_opus_destroy);  /* deinitalize a codec handle using this implementation */
-
+               codec_interface->implementations->codec_control = switch_opus_control;
                settings.stereo = 1;
                dft_fmtp = gen_fmtp(&settings, pool);
                switch_core_codec_add_implementation(pool, codec_interface, SWITCH_CODEC_TYPE_AUDIO,    /* enumeration defining the type of the codec */
@@ -825,6 +880,7 @@ SWITCH_MODULE_LOAD_FUNCTION(mod_opus_load)
                                                                                         switch_opus_encode,    /* function to encode raw data into encoded data */
                                                                                         switch_opus_decode,    /* function to decode encoded data into raw data */
                                                                                         switch_opus_destroy);  /* deinitalize a codec handle using this implementation */
+               codec_interface->implementations->codec_control = switch_opus_control;
         
                bytes += 160;
                samples += 480;