bink: pass Bink version to audio decoder through extradata instead of codec_tag.

This is needed because not all players (e.g. MPlayer) are able to distinguish
two different Bink audio decoders when codec_tag is set.
Signed-off-by: Anton Khirnov <anton@khirnov.net>

libavcodec/binkaudio.c

@@ -90,7 +90,7 @@ static av_cold int decode_init(AVCodecContext *avctx)
         return -1;
     }
 
-    s->version_b = avctx->codec_tag == MKTAG('B','I','K','b');
+    s->version_b = avctx->extradata && avctx->extradata[3] == 'b';
 
     if (avctx->codec->id == CODEC_ID_BINKAUDIO_RDFT) {
         // audio is already interleaved for the RDFT format variant

libavformat/bink.c

@@ -134,13 +134,18 @@ static int read_header(AVFormatContext *s, AVFormatParameters *ap)
             if (!ast)
                 return AVERROR(ENOMEM);
             ast->codec->codec_type  = AVMEDIA_TYPE_AUDIO;
-            ast->codec->codec_tag   = vst->codec->codec_tag;
+            ast->codec->codec_tag   = 0;
             ast->codec->sample_rate = avio_rl16(pb);
             av_set_pts_info(ast, 64, 1, ast->codec->sample_rate);
             flags = avio_rl16(pb);
             ast->codec->codec_id = flags & BINK_AUD_USEDCT ?
                                    CODEC_ID_BINKAUDIO_DCT : CODEC_ID_BINKAUDIO_RDFT;
             ast->codec->channels = flags & BINK_AUD_STEREO ? 2 : 1;
+            ast->codec->extradata = av_mallocz(4 + FF_INPUT_BUFFER_PADDING_SIZE);
+            if (!ast->codec->extradata)
+                return AVERROR(ENOMEM);
+            ast->codec->extradata_size = 4;
+            AV_WL32(ast->codec->extradata, vst->codec->codec_tag);
         }
 
         for (i = 0; i < bink->num_audio_tracks; i++)