lavf: allow BSFs to drop packets.

If pkt->size == 0 && pkt->side_data_elems == 0 after bsf->filter()
returns, the packet is considered dropped.

1 files changed, 3 insertions, 1 deletions

diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index a558f2d392..ccb8033f9a 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -2850,7 +2850,9 @@ int avformat_queue_attached_pictures(AVFormatContext *s);
  * Apply a list of bitstream filters to a packet.
  *
  * @param codec AVCodecContext, usually from an AVStream
- * @param pkt the packet to apply filters to
+ * @param pkt the packet to apply filters to. If, on success, the returned
+ *        packet has size == 0 and side_data_elems == 0, it indicates that
+ *        the packet should be dropped
  * @param bsfc a NULL-terminated list of filters to apply
  * @return  >=0 on success;
  *          AVERROR code on failure