lavc: support extracting audio service type from side data

libavcodec/utils.c

@@ -1397,6 +1397,13 @@ int attribute_align_arg avcodec_encode_audio2(AVCodecContext *avctx,
         frame = &tmp;
     }
 
+    /* extract audio service type metadata */
+    if (frame) {
+        AVFrameSideData *sd = av_frame_get_side_data(frame, AV_FRAME_DATA_AUDIO_SERVICE_TYPE);
+        if (sd && sd->size >= sizeof(enum AVAudioServiceType))
+            avctx->audio_service_type = *(enum AVAudioServiceType*)sd->data;
+    }
+
     /* check for valid frame size */
     if (frame) {
         if (avctx->codec->capabilities & CODEC_CAP_SMALL_LAST_FRAME) {