Fix channel order for some MLP samples.

libavcodec/mlpdec.c

@@ -133,6 +133,9 @@ typedef struct MLPDecodeContext {
     //! Index of the last substream to decode - further substreams are skipped.
     uint8_t     max_decoded_substream;
 
+    //! Stream needs channel reordering to comply with FFmpeg's channel order
+    uint8_t     needs_reordering;
+
     //! number of PCM samples contained in each frame
     int         access_unit_size;
     //! next power of two above the number of samples in each frame
@@ -326,6 +329,8 @@ static int read_major_sync(MLPDecodeContext *m, GetBitContext *gb)
     for (substr = 0; substr < MAX_SUBSTREAMS; substr++)
         m->substream[substr].restart_seen = 0;
 
+    m->needs_reordering = mh.channels_mlp >= 18 && mh.channels_mlp <= 20;
+
     return 0;
 }
 
@@ -436,6 +441,19 @@ static int read_restart_header(MLPDecodeContext *m, GetBitContext *gbp,
         s->ch_assign[ch_assign] = ch;
     }
 
+    if (m->avctx->codec_id == CODEC_ID_MLP && m->needs_reordering) {
+        if (m->avctx->channel_layout == (AV_CH_LAYOUT_2_2|AV_CH_LOW_FREQUENCY) ||
+            m->avctx->channel_layout == AV_CH_LAYOUT_5POINT0) {
+            int i = s->ch_assign[4];
+            s->ch_assign[4] = s->ch_assign[3];
+            s->ch_assign[3] = s->ch_assign[2];
+            s->ch_assign[2] = i;
+        } else if (m->avctx->channel_layout == AV_CH_LAYOUT_5POINT1) {
+            FFSWAP(int, s->ch_assign[2], s->ch_assign[4]);
+            FFSWAP(int, s->ch_assign[3], s->ch_assign[5]);
+        }
+    }
+
     checksum = ff_mlp_restart_checksum(buf, get_bits_count(gbp) - start_count);
 
     if (checksum != get_bits(gbp, 8))