Add av_shrink_packet function for use in av_get_packet that reduces pkt->size

and ensures the following padding is correctly initialized to 0.

Originally committed as revision 18378 to svn://svn.ffmpeg.org/ffmpeg/trunk

2 files changed, 15 insertions, 0 deletions

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 218e236e9b..f500151e85 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -2655,6 +2655,14 @@ void av_init_packet(AVPacket *pkt);
 int av_new_packet(AVPacket *pkt, int size);
 
 /**
+ * Reduce packet size, correctly zeroing padding
+ *
+ * @param pkt packet
+ * @param size new size
+ */
+void av_shrink_packet(AVPacket *pkt, int size);
+
+/**
  * @warning This is a hack - the packet memory allocation stuff is broken. The
  * packet is allocated if it was not really allocated.
  */
diff --git a/libavcodec/avpacket.c b/libavcodec/avpacket.c
index 107afb3817..d91ee3a10d 100644
--- a/libavcodec/avpacket.c
+++ b/libavcodec/avpacket.c
@@ -62,6 +62,13 @@ int av_new_packet(AVPacket *pkt, int size)
     return 0;
 }
 
+void av_shrink_packet(AVPacket *pkt, int size)
+{
+    if (pkt->size <= size) return;
+    pkt->size = size;
+    memset(pkt->data + size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
+}
+
 int av_dup_packet(AVPacket *pkt)
 {
     if (((pkt->destruct == av_destruct_packet_nofree) || (pkt->destruct == NULL)) && pkt->data) {