[FFmpeg-devel] [PATCH] Parse ogg/flac header again after processing a new chained ogg bitstream.

[Romain Beauxis]

This patch makes sure that ogg/flac headers are parsed again when
encountering a new logic stream inside a chained ogg bistream[1].

This patches makes it possible to retrieve metadata in chained ogg/flac
bitstreams. It is particularly important because ogg/flac is one of the
only (if not the only one) lossless container supported over HTTP/icecast.

The patch has been tested with various ogg/flac encoders and appears to
work fine with ffmpeg.

1: https://xiph.org/ogg/doc/oggstream.html

---
 libavformat/oggdec.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/libavformat/oggdec.c b/libavformat/oggdec.c
index 5339fdd32c..d986e19817 100644
--- a/libavformat/oggdec.c
+++ b/libavformat/oggdec.c
@@ -239,8 +239,11 @@ static int ogg_replace_stream(AVFormatContext *s, uint32_t serial, char *magic,
     os->start_trimming = 0;
     os->end_trimming = 0;
 
-    /* Chained files have extradata as a new packet */
-    if (codec == &ff_opus_codec)
+    /* Parse opus and flac header on new chained bitstreams.
+     * For opus, header contains required extradata as new packet.
+     * For both formats, this makes it possible to read chained metadata. */
+    if (codec == &ff_opus_codec ||
+        codec == &ff_flac_codec)
         os->header = -1;
 
     return i;
-- 
2.39.5 (Apple Git-154)