Set blkalign to maximum framesize to allow playback on WMP (see issue 2455 and issue 2446).

Originally committed as revision 26167 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/riff.c

@@ -373,6 +373,10 @@ int ff_put_wav_header(ByteIOContext *pb, AVCodecContext *enc)
     if (enc->codec_id == CODEC_ID_MP2 || enc->codec_id == CODEC_ID_MP3 || enc->codec_id == CODEC_ID_AC3) {
         blkalign = enc->frame_size; //this is wrong, but it seems many demuxers do not work if this is set correctly
         //blkalign = 144 * enc->bit_rate/enc->sample_rate;
+        //For high bitrate AC-3, set blkalign to maximum bytes per frame value
+        //to allow playback on WMP and MPlayer
+        if (enc->bit_rate > 384000)
+            blkalign = 3840;
     } else if (enc->codec_id == CODEC_ID_ADPCM_G726) { //
         blkalign = 1;
     } else if (enc->block_align != 0) { /* specified by the codec */