truehd: support up to 3 substreams.

Originally committed as revision 18072 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/mlp.h

@@ -34,10 +34,10 @@
  */
 #define MAX_MATRICES        15
 
-/** Maximum number of substreams that can be decoded. This could also be set
- *  higher, but I haven't seen any examples with more than two.
+/** Maximum number of substreams that can be decoded.
+ *  MLP's limit is 2. TrueHD supports at least up to 3.
  */
-#define MAX_SUBSTREAMS      2
+#define MAX_SUBSTREAMS      3
 
 /** maximum sample frequency seen in files */
 #define MAX_SAMPLERATE      192000

libavcodec/mlpdec.c

@@ -280,6 +280,10 @@ static int read_major_sync(MLPDecodeContext *m, GetBitContext *gb)
 
     if (mh.num_substreams == 0)
         return -1;
+    if (m->avctx->codec_id == CODEC_ID_MLP && mh.num_substreams > 2) {
+        av_log(m->avctx, AV_LOG_ERROR, "MLP only supports up to 2 substreams.\n");
+        return -1;
+    }
     if (mh.num_substreams > MAX_SUBSTREAMS) {
         av_log(m->avctx, AV_LOG_ERROR,
                "Number of substreams %d is larger than the maximum supported "