libavformat: Use avcodec_copy_context for chained muxers

This avoids having the chained AVStream->codec point to the same
AVCodecContext owned by the outer AVStream. The downside is that
changes to the AVCodecContext made after calling av_write_header
cannot be detected automatically within the chained muxer.

This avoids having to manually unlink the chained AVStream->codec
by setting it to null before freeing the chained muxer via generic
freeing functions.

Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>

1 files changed, 3 insertions, 5 deletions

diff --git a/libavformat/rtpenc_chain.c b/libavformat/rtpenc_chain.c
index 19ea98f643..09b4ebd7c3 100644
--- a/libavformat/rtpenc_chain.c
+++ b/libavformat/rtpenc_chain.c
@@ -50,11 +50,7 @@ AVFormatContext *ff_rtp_chain_mux_open(AVFormatContext *s, AVStream *st,
     /* Set the synchronized start time. */
     rtpctx->start_time_realtime = s->start_time_realtime;
 
-    /* Remove the local codec, link to the original codec
-     * context instead, to give the rtp muxer access to
-     * codec parameters. */
-    av_free(rtpctx->streams[0]->codec);
-    rtpctx->streams[0]->codec = st->codec;
+    avcodec_copy_context(rtpctx->streams[0]->codec, st->codec);
 
     if (handle) {
         url_fdopen(&rtpctx->pb, handle);
@@ -70,6 +66,8 @@ AVFormatContext *ff_rtp_chain_mux_open(AVFormatContext *s, AVStream *st,
             url_close_dyn_buf(rtpctx->pb, &ptr);
             av_free(ptr);
         }
+        av_free(rtpctx->streams[0]->codec->extradata);
+        av_free(rtpctx->streams[0]->codec);
         av_free(rtpctx->streams[0]->info);
         av_free(rtpctx->streams[0]);
         av_free(rtpctx);