[FFmpeg-devel] [PATCH 3/4] avfiltergraph: document a catch in request_oldest().

Nicolas George nicolas.george at normalesup.org
Tue Jul 17 18:13:18 CEST 2012

This one is tricky. Consider a graph with two sink links, A and B.
request_oldest() requests on A, and A returns EOF. This EOF causes
a filter to flush pending frames to B; they are unrequested.
Then request_oldest() moves on to B, and B returns EOF.

Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
 libavfilter/avfiltergraph.h |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavfilter/avfiltergraph.h b/libavfilter/avfiltergraph.h
index c55b549..0bb6d41 100644
--- a/libavfilter/avfiltergraph.h
+++ b/libavfilter/avfiltergraph.h
@@ -255,6 +255,9 @@ char *avfilter_graph_dump(AVFilterGraph *graph, const char *options);
  * of a filtergraph, only a convenience function to help drain a filtergraph
  * in a balanced way under normal circumstances.
+ * Also note that AVERROR_EOF does not mean that frames did not arrive on
+ * some of the sinks during the process.
+ *
  * @return  the return value of ff_request_frame,
  *          or AVERROR_EOF of all links returned AVERROR_EOF.

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