Fix detection of audio codec in K70707-ARIA229.flv.

Fixes issue760.

Originally committed as revision 16254 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/flvdec.c

@@ -391,10 +391,12 @@ static int flv_read_packet(AVFormatContext *s, AVPacket *pkt)
     }
 
     if(is_audio){
-        if(!st->codec->channels || !st->codec->sample_rate || !st->codec->bits_per_coded_sample || (!st->codec->codec_id && !st->codec->codec_tag)) {
+        if(!st->codec->channels || !st->codec->sample_rate || !st->codec->bits_per_coded_sample) {
             st->codec->channels = (flags & FLV_AUDIO_CHANNEL_MASK) == FLV_STEREO ? 2 : 1;
             st->codec->sample_rate = (44100 << ((flags & FLV_AUDIO_SAMPLERATE_MASK) >> FLV_AUDIO_SAMPLERATE_OFFSET) >> 3);
             st->codec->bits_per_coded_sample = (flags & FLV_AUDIO_SAMPLESIZE_MASK) ? 16 : 8;
+        }
+        if(!st->codec->codec_id){
             flv_set_audio_codec(s, st, flags & FLV_AUDIO_CODECID_MASK);
         }
     }else{