lavc: add a packet side data type for VBV-like parameters

doc/APIchanges

@@ -16,6 +16,7 @@ API changes, most recent first:
 2015-xx-xx - xxxxxxx - lavc 57.11.0 - avcodec.h
   xxxxxxx - Add av_packet_add_side_data().
   xxxxxxx - Add AVCodecContext.coded_side_data.
+  xxxxxxx - Add AVCPBProperties API.
 
 2015-xx-xx - xxxxxxx - lavc 57.9.1 - avcodec.h
   Deprecate rtp_callback without replacement, i.e. it won't be possible to

libavcodec/avcodec.h

@@ -1036,6 +1036,44 @@ typedef struct AVPanScan{
     int16_t position[3][2];
 }AVPanScan;
 
+/**
+ * This structure describes the bitrate properties of an encoded bitstream. It
+ * roughly corresponds to a subset the VBV parameters for MPEG-2 or HRD
+ * parameters for H.264/HEVC.
+ */
+typedef struct AVCPBProperties {
+    /**
+     * Maximum bitrate of the stream, in bits per second.
+     * Zero if unknown or unspecified.
+     */
+    int max_bitrate;
+    /**
+     * Minimum bitrate of the stream, in bits per second.
+     * Zero if unknown or unspecified.
+     */
+    int min_bitrate;
+    /**
+     * Average bitrate of the stream, in bits per second.
+     * Zero if unknown or unspecified.
+     */
+    int avg_bitrate;
+
+    /**
+     * The size of the buffer to which the ratecontrol is applied, in bits.
+     * Zero if unknown or unspecified.
+     */
+    int buffer_size;
+
+    /**
+     * The delay between the time the packet this structure is associated with
+     * is received and the time when it should be decoded, in periods of a 27MHz
+     * clock.
+     *
+     * UINT64_MAX when unknown or unspecified.
+     */
+    uint64_t vbv_delay;
+} AVCPBProperties;
+
 #if FF_API_QSCALE_TYPE
 #define FF_QSCALE_TYPE_MPEG1 0
 #define FF_QSCALE_TYPE_MPEG2 1
@@ -1137,6 +1175,11 @@ enum AVPacketSideDataType {
      * e.g. no decoder available for codec.
      */
     AV_PKT_DATA_FALLBACK_TRACK,
+
+    /**
+     * This side data corresponds to the AVCPBProperties struct.
+     */
+    AV_PKT_DATA_CPB_PROPERTIES,
 };
 
 typedef struct AVPacketSideData {
@@ -4630,6 +4673,17 @@ const AVCodecDescriptor *avcodec_descriptor_next(const AVCodecDescriptor *prev);
  */
 const AVCodecDescriptor *avcodec_descriptor_get_by_name(const char *name);
 
+/**
+ * Allocate a CPB properties structure and initialize its fields to default
+ * values.
+ *
+ * @param size if non-NULL, the size of the allocated struct will be written
+ *             here. This is useful for embedding it in side data.
+ *
+ * @return the newly allocated struct or NULL on failure
+ */
+AVCPBProperties *av_cpb_properties_alloc(size_t *size);
+
 /**
  * @}
  */

libavcodec/utils.c

@@ -2369,3 +2369,17 @@ const uint8_t *avpriv_find_start_code(const uint8_t *restrict p,
 
     return p + 4;
 }
+
+AVCPBProperties *av_cpb_properties_alloc(size_t *size)
+{
+    AVCPBProperties *props = av_mallocz(sizeof(AVCPBProperties));
+    if (!props)
+        return NULL;
+
+    if (size)
+        *size = sizeof(*props);
+
+    props->vbv_delay = UINT64_MAX;
+
+    return props;
+}