avpacket: Add a function for shrinking already allocated side data

Signed-off-by: Martin Storsjö <martin@martin.st>

doc/APIchanges

@@ -12,6 +12,9 @@ libavutil:   2011-04-18
 
 API changes, most recent first:
 
+2012-xx-xx - xxxxxxx - lavc 54.3.0 - avcodec.h
+  Add av_packet_shrink_side_data.
+
 2012-xx-xx - xxxxxxx - lavf 54.2.0 - avformat.h
   Add AVStream.attached_pic and AV_DISPOSITION_ATTACHED_PIC,
   used for dealing with attached pictures/cover art.

libavcodec/avcodec.h

@@ -3078,6 +3078,17 @@ void av_free_packet(AVPacket *pkt);
 uint8_t* av_packet_new_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                                  int size);
 
+/**
+ * Shrink the already allocated side data buffer
+ *
+ * @param pkt packet
+ * @param type side information type
+ * @param size new side information size
+ * @return 0 on success, < 0 on failure
+ */
+int av_packet_shrink_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
+                               int size);
+
 /**
  * Get side information from packet.
  *

libavcodec/avpacket.c

@@ -196,3 +196,19 @@ uint8_t* av_packet_get_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
     }
     return NULL;
 }
+
+int av_packet_shrink_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
+                               int size)
+{
+    int i;
+
+    for (i = 0; i < pkt->side_data_elems; i++) {
+        if (pkt->side_data[i].type == type) {
+            if (size > pkt->side_data[i].size)
+                return AVERROR(ENOMEM);
+            pkt->side_data[i].size = size;
+            return 0;
+        }
+    }
+    return AVERROR(ENOENT);
+}

libavcodec/version.h

@@ -21,7 +21,7 @@
 #define AVCODEC_VERSION_H
 
 #define LIBAVCODEC_VERSION_MAJOR 54
-#define LIBAVCODEC_VERSION_MINOR  2
+#define LIBAVCODEC_VERSION_MINOR  3
 #define LIBAVCODEC_VERSION_MICRO  0
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \