lavf: add a temporary compat layer for the channel layout API change

Mediates between old-style (de)muxers and new-style callers. Will be
removed once all the (de)muxers are converted to the new API.

Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/demux.c

@@ -194,6 +194,18 @@ static int update_stream_avctx(AVFormatContext *s)
             sti->parser = NULL;
         }
 
+        /* if the demuxer exports old channel layouts, convert it to new */
+        if (!st->codecpar->ch_layout.nb_channels &&
+            st->codecpar->channels) {
+            if (st->codecpar->channel_layout) {
+                av_channel_layout_from_mask(&st->codecpar->ch_layout,
+                                            st->codecpar->channel_layout);
+            } else {
+                st->codecpar->ch_layout.order       = AV_CHANNEL_ORDER_UNSPEC;
+                st->codecpar->ch_layout.nb_channels = st->codecpar->channels;
+            }
+        }
+
         /* update internal codec context, for the parser */
         ret = avcodec_parameters_to_context(sti->avctx, st->codecpar);
         if (ret < 0)

libavformat/mux.c

@@ -272,6 +272,16 @@ static int init_muxer(AVFormatContext *s, AVDictionary **options)
                 ret = AVERROR(EINVAL);
                 goto fail;
             }
+
+            /* if the new-style channel layout is set, convert it to old one
+             * for old-style muxers */
+            if (par->ch_layout.nb_channels &&
+                !par->channels) {
+                par->channels       = par->ch_layout.nb_channels;
+                par->channel_layout = par->ch_layout.order == AV_CHANNEL_ORDER_NATIVE ?
+                                      par->ch_layout.u.mask : 0;
+            }
+
             if (!par->block_align)
                 par->block_align = par->channels *
                                    av_get_bits_per_sample(par->codec_id) >> 3;