lavf/mpegtsenc: Fix stream_type for low sample rate MP2/MP3.

libavformat/mpegtsenc.c

@@ -318,7 +318,12 @@ static int mpegts_write_pmt(AVFormatContext *s, MpegTSService *service)
             break;
         case AV_CODEC_ID_MP2:
         case AV_CODEC_ID_MP3:
-            stream_type = STREAM_TYPE_AUDIO_MPEG1;
+            if (   st->codec->sample_rate > 0
+                && st->codec->sample_rate < 32000) {
+                stream_type = STREAM_TYPE_AUDIO_MPEG2;
+            } else {
+                stream_type = STREAM_TYPE_AUDIO_MPEG1;
+            }
             break;
         case AV_CODEC_ID_AAC:
             stream_type = (ts->flags & MPEGTS_FLAG_AAC_LATM)