mlp_parser: Drop in-parser downmix functionality

request_channel_layout is a decoder option and it makes no sense
to have it in a parser.

This feature was needed in the past when the decoder was allowed
to reuse the avctx from the demuxer. Nowadays the decoder receives
only the parameters from it, already containing the real channel
layout (and the correct request_channel_layout option).

After initialization the decoder overwrites the channel layout
with the downmixed one that is actually output, so there is no need
to preserve this functionality in the parser.
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

libavcodec/mlp_parser.c

@@ -120,11 +120,6 @@ static uint64_t truehd_layout(int chanmap)
     return layout;
 }
 
-int ff_mlp_channel_layout_subset(uint64_t channel_layout, uint64_t mask)
-{
-    return channel_layout && ((channel_layout & mask) == channel_layout);
-}
-
 static int mlp_get_major_sync_size(const uint8_t * buf, int bufsize)
 {
     int has_extension, extensions = 0;
@@ -336,8 +331,6 @@ static int mlp_parse(AVCodecParserContext *s,
     } else {
         BitstreamContext bc;
         MLPHeaderInfo mh;
-        int stereo_requested = ff_mlp_channel_layout_subset(avctx->request_channel_layout,
-                                                            AV_CH_LAYOUT_STEREO);
 
         bitstream_init8(&bc, buf + 4, buf_size - 4);
         if (ff_mlp_read_major_sync(avctx, &mh, &bc) < 0)
@@ -353,21 +346,11 @@ static int mlp_parse(AVCodecParserContext *s,
 
         if (mh.stream_type == 0xbb) {
             /* MLP stream */
-            if (stereo_requested && mh.num_substreams > 1) {
-                avctx->channels       = 2;
-                avctx->channel_layout = AV_CH_LAYOUT_STEREO;
-            } else {
-                avctx->channels       = mh.channels_mlp;
-                avctx->channel_layout = mh.channel_layout_mlp;
-            }
+            avctx->channels       = mh.channels_mlp;
+            avctx->channel_layout = mh.channel_layout_mlp;
         } else { /* mh.stream_type == 0xba */
             /* TrueHD stream */
-            if (stereo_requested && mh.num_substreams > 1) {
-                avctx->channels       = 2;
-                avctx->channel_layout = AV_CH_LAYOUT_STEREO;
-            } else if (!mh.channels_thd_stream2 ||
-                       ff_mlp_channel_layout_subset(avctx->request_channel_layout,
-                                                    mh.channel_layout_thd_stream1)) {
+            if (!mh.channels_thd_stream2) {
                 avctx->channels       = mh.channels_thd_stream1;
                 avctx->channel_layout = mh.channel_layout_thd_stream1;
             } else {

libavcodec/mlp_parser.h

@@ -63,6 +63,4 @@ typedef struct MLPHeaderInfo
 
 int ff_mlp_read_major_sync(void *log, MLPHeaderInfo *mh, BitstreamContext *bc);
 
-int ff_mlp_channel_layout_subset(uint64_t channel_layout, uint64_t mask);
-
 #endif /* AVCODEC_MLP_PARSER_H */

libavcodec/mlpdec.c

@@ -178,6 +178,11 @@ static const uint64_t thd_channel_order[] = {
     AV_CH_LOW_FREQUENCY_2,                                   // LFE2
 };
 
+static int mlp_channel_layout_subset(uint64_t channel_layout, uint64_t mask)
+{
+    return channel_layout && ((channel_layout & mask) == channel_layout);
+}
+
 static uint64_t thd_channel_layout_extract_channel(uint64_t channel_layout,
                                                    int index)
 {
@@ -511,7 +516,7 @@ static int read_restart_header(MLPDecodeContext *m, BitstreamContext *bc,
     s->max_channel        = max_channel;
     s->max_matrix_channel = max_matrix_channel;
 
-    if (ff_mlp_channel_layout_subset(m->avctx->request_channel_layout, s->mask) &&
+    if (mlp_channel_layout_subset(m->avctx->request_channel_layout, s->mask) &&
         m->max_decoded_substream > substr) {
         av_log(m->avctx, AV_LOG_DEBUG,
                "Extracting %d-channel downmix (0x%"PRIx64") from substream %d. "