lavf/dv: set audio bitrate only at stream creation

Demuxers are not supposed to update AVCodecParameters after the stream
was seen by the caller. This value is not important enough to support
dynamic updates for.

libavformat/dv.c

@@ -280,6 +280,7 @@ static int dv_extract_audio_info(DVDemuxContext *c, const uint8_t *frame)
             c->ast[i]->codecpar->codec_id   = AV_CODEC_ID_PCM_S16LE;
             c->ast[i]->codecpar->ch_layout  = (AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO;
             c->ast[i]->start_time           = 0;
+            c->ast[i]->codecpar->bit_rate   = 2 * dv_audio_frequency[freq] * 16;
 
             c->audio_pkt[i].size         = 0;
             c->audio_pkt[i].data         = c->audio_buf[i];
@@ -290,7 +291,6 @@ static int dv_extract_audio_info(DVDemuxContext *c, const uint8_t *frame)
             c->audio_pkt[i].pos          = -1;
         }
         c->ast[i]->codecpar->sample_rate    = dv_audio_frequency[freq];
-        c->ast[i]->codecpar->bit_rate       = 2 * dv_audio_frequency[freq] * 16;
     }
     c->ach = ach;