lavc: Add refcounted api to AVPacket

Provide a clean way to manipulate packets.

doc/APIchanges

@@ -13,6 +13,10 @@ libavutil:     2012-10-22
 
 API changes, most recent first:
 
+2013-08-xx - xxxxxxx - lavc 55.16.0 - avcodec.h
+  Extend AVPacket API with av_packet_unref, av_packet_ref,
+  av_packet_move_ref, av_packet_copy_props, av_packet_free_side_data.
+
 2013-08-xx - xxxxxxx - lavc 55.13.0 - avcodec.h
   Deprecate the bitstream-related members from struct AVVDPAUContext.
   The bistream buffers no longer need to be explicitly freed.

libavcodec/avcodec.h

@@ -3228,6 +3228,66 @@ int av_packet_shrink_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
 uint8_t* av_packet_get_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
                                  int *size);
 
+/**
+ * Convenience function to free all the side data stored.
+ * All the other fields stay untouched.
+ *
+ * @param pkt packet
+ */
+void av_packet_free_side_data(AVPacket *pkt);
+
+/**
+ * Setup a new reference to the data described by a given packet
+ *
+ * If src is reference-counted, setup dst as a new reference to the
+ * buffer in src. Otherwise allocate a new buffer in dst and copy the
+ * data from src into it.
+ *
+ * All the other fields are copied from src.
+ *
+ * @see av_packet_unref
+ *
+ * @param dst Destination packet
+ * @param src Source packet
+ *
+ * @return 0 on success, a negative AVERROR on error.
+ */
+int av_packet_ref(AVPacket *dst, AVPacket *src);
+
+/**
+ * Wipe the packet.
+ *
+ * Unreference the buffer referenced by the packet and reset the
+ * remaining packet fields to their default values.
+ *
+ * @param pkt The packet to be unreferenced.
+ */
+void av_packet_unref(AVPacket *pkt);
+
+/**
+ * Move every field in src to dst and reset src.
+ *
+ * @see av_packet_unref
+ *
+ * @param src Source packet, will be reset
+ * @param dst Destination packet
+ */
+void av_packet_move_ref(AVPacket *dst, AVPacket *src);
+
+/**
+ * Copy only "properties" fields from src to dst.
+ *
+ * Properties for the purpose of this function are all the fields
+ * beside those related to the packet data (buf, data, size)
+ *
+ * @param dst Destination packet
+ * @param src Source packet
+ *
+ * @return 0 on success AVERROR on failure.
+ *
+ */
+int av_packet_copy_props(AVPacket *dst, const AVPacket *src);
+
 /**
  * @}
  */

libavcodec/avpacket.c

@@ -26,8 +26,8 @@
 #include "libavutil/internal.h"
 #include "libavutil/mem.h"
 #include "avcodec.h"
-
 #if FF_API_DESTRUCT_PACKET
+
 void av_destruct_packet(AVPacket *pkt)
 {
     av_free(pkt->data);
@@ -62,18 +62,26 @@ FF_ENABLE_DEPRECATION_WARNINGS
     pkt->side_data_elems      = 0;
 }
 
-int av_new_packet(AVPacket *pkt, int size)
+static int packet_alloc(AVBufferRef **buf, int size)
 {
-    AVBufferRef *buf = NULL;
-
     if ((unsigned)size >= (unsigned)size + FF_INPUT_BUFFER_PADDING_SIZE)
         return AVERROR(EINVAL);
 
-    av_buffer_realloc(&buf, size + FF_INPUT_BUFFER_PADDING_SIZE);
+    av_buffer_realloc(buf, size + FF_INPUT_BUFFER_PADDING_SIZE);
     if (!buf)
         return AVERROR(ENOMEM);
 
-    memset(buf->data + size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
+    memset((*buf)->data + size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
+
+    return 0;
+}
+
+int av_new_packet(AVPacket *pkt, int size)
+{
+    AVBufferRef *buf = NULL;
+    int ret = packet_alloc(&buf, size);
+    if (ret < 0)
+        return ret;
 
     av_init_packet(pkt);
     pkt->buf      = buf;
@@ -221,11 +229,18 @@ failed_alloc:
     return AVERROR(ENOMEM);
 }
 
+void av_packet_free_side_data(AVPacket *pkt)
+{
+    int i;
+    for (i = 0; i < pkt->side_data_elems; i++)
+        av_free(pkt->side_data[i].data);
+    av_freep(&pkt->side_data);
+    pkt->side_data_elems = 0;
+}
+
 void av_free_packet(AVPacket *pkt)
 {
     if (pkt) {
-        int i;
-
 FF_DISABLE_DEPRECATION_WARNINGS
         if (pkt->buf)
             av_buffer_unref(&pkt->buf);
@@ -238,10 +253,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
         pkt->data            = NULL;
         pkt->size            = 0;
 
-        for (i = 0; i < pkt->side_data_elems; i++)
-            av_free(pkt->side_data[i].data);
-        av_freep(&pkt->side_data);
-        pkt->side_data_elems = 0;
+        av_packet_free_side_data(pkt);
     }
 }
 
@@ -300,3 +312,71 @@ int av_packet_shrink_side_data(AVPacket *pkt, enum AVPacketSideDataType type,
     }
     return AVERROR(ENOENT);
 }
+
+int av_packet_copy_props(AVPacket *dst, const AVPacket *src)
+{
+    int i;
+
+    dst->pts                  = src->pts;
+    dst->dts                  = src->dts;
+    dst->pos                  = src->pos;
+    dst->duration             = src->duration;
+    dst->convergence_duration = src->convergence_duration;
+    dst->flags                = src->flags;
+    dst->stream_index         = src->stream_index;
+    dst->side_data_elems      = src->side_data_elems;
+
+    for (i = 0; i < src->side_data_elems; i++) {
+         enum AVPacketSideDataType type = src->side_data[i].type;
+         int size          = src->side_data[i].size;
+         uint8_t *src_data = src->side_data[i].data;
+         uint8_t *dst_data = av_packet_new_side_data(dst, type, size);
+
+        if (!dst_data) {
+            av_packet_free_side_data(dst);
+            return AVERROR(ENOMEM);
+        }
+        memcpy(dst_data, src_data, size);
+    }
+
+    return 0;
+}
+
+void av_packet_unref(AVPacket *pkt)
+{
+    av_packet_free_side_data(pkt);
+    av_buffer_unref(&pkt->buf);
+    av_init_packet(pkt);
+    pkt->data = NULL;
+    pkt->size = 0;
+}
+
+int av_packet_ref(AVPacket *dst, AVPacket *src)
+{
+    int ret;
+
+    ret = av_packet_copy_props(dst, src);
+    if (ret < 0)
+        return ret;
+
+    if (!src->buf) {
+        ret = packet_alloc(&dst->buf, src->size);
+        if (ret < 0)
+            goto fail;
+        memcpy(dst->buf->data, src->data, src->size);
+    } else
+        dst->buf = av_buffer_ref(src->buf);
+
+    dst->size = src->size;
+    dst->data = dst->buf->data;
+    return 0;
+fail:
+    av_packet_free_side_data(dst);
+    return ret;
+}
+
+void av_packet_move_ref(AVPacket *dst, AVPacket *src)
+{
+    *dst = *src;
+    av_init_packet(src);
+}

libavcodec/version.h

@@ -27,7 +27,7 @@
  */
 
 #define LIBAVCODEC_VERSION_MAJOR 55
-#define LIBAVCODEC_VERSION_MINOR 15
+#define LIBAVCODEC_VERSION_MINOR 16
 #define LIBAVCODEC_VERSION_MICRO  0
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \