[libav-devel] [PATCH] Set protocol-level metadata in AVFormatContext any time a packet is read.

Andrew Stone andrew at clovar.com
Fri Jun 13 19:33:21 CEST 2014


If any option named "metadata" is set inside the context, it is pulled up to
the context and then the option is cleared.

Rather than maintaining a list of metadata changes and presenting them to
an application, the application must poll the metadata it's interested in
by using av_dict_version(). Typically, since this data is only used for
display, there's no need to track what actually changes as updating displayed
metadata with identical information should be acceptable.
---

As promised, here is the patch, stripped to the core and only updating metadata it sees
set as an option.

 libavformat/utils.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/libavformat/utils.c b/libavformat/utils.c
index de66c6b..ccd5d66 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -1027,6 +1027,7 @@ static int read_from_packet_buffer(AVPacketList **pkt_buffer,
 static int read_frame_internal(AVFormatContext *s, AVPacket *pkt)
 {
     int ret = 0, i, got_packet = 0;
+    AVDictionary *metadata = NULL;

     av_init_packet(pkt);

@@ -1102,6 +1103,13 @@ static int read_frame_internal(AVFormatContext *s, AVPacket *pkt)
     if (!got_packet && s->parse_queue)
         ret = read_from_packet_buffer(&s->parse_queue, &s->parse_queue_end, pkt);

+    av_opt_get_dict_val(s, "metadata", AV_OPT_SEARCH_CHILDREN, &metadata);
+    if (metadata) {
+        av_dict_copy(&s->metadata, metadata, 0);
+        av_dict_free(&metadata);
+        av_opt_set_dict_val(s, "metadata", NULL, AV_OPT_SEARCH_CHILDREN);
+    }
+
     if (s->debug & FF_FDEBUG_TS)
         av_log(s, AV_LOG_DEBUG,
                "read_frame_internal stream=%d, pts=%"PRId64", dts=%"PRId64", "
--
2.0.0



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