libavcodec: Define a side data type for parameter changes

Also define a codec capability for codecs that can handle
parameters changed externally between decoded packets.

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

libavcodec/avcodec.h

@@ -773,6 +773,10 @@ typedef struct RcOverride{
  * Codec supports slice-based (or partition-based) multithreading.
  */
 #define CODEC_CAP_SLICE_THREADS    0x2000
+/**
+ * Codec supports changed parameters at any point.
+ */
+#define CODEC_CAP_PARAM_CHANGE     0x4000
 
 //The following defines may change, don't expect compatibility if you use them.
 #define MB_TYPE_INTRA4x4   0x0001
@@ -856,6 +860,7 @@ typedef struct AVPanScan{
 enum AVPacketSideDataType {
     AV_PKT_DATA_PALETTE,
     AV_PKT_DATA_NEW_EXTRADATA,
+    AV_PKT_DATA_PARAM_CHANGE,
 };
 
 typedef struct AVPacket {
@@ -924,6 +929,27 @@ typedef struct AVPacket {
 #define AV_PKT_FLAG_KEY     0x0001 ///< The packet contains a keyframe
 #define AV_PKT_FLAG_CORRUPT 0x0002 ///< The packet content is corrupted
 
+/**
+ * An AV_PKT_DATA_PARAM_CHANGE side data packet is laid out as follows:
+ * u32le param_flags
+ * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT)
+ *     s32le channel_count
+ * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_LAYOUT)
+ *     u64le channel_layout
+ * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE)
+ *     s32le sample_rate
+ * if (param_flags & AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS)
+ *     s32le width
+ *     s32le height
+ */
+
+enum AVSideDataParamChangeFlags {
+    AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_COUNT  = 0x0001,
+    AV_SIDE_DATA_PARAM_CHANGE_CHANNEL_LAYOUT = 0x0002,
+    AV_SIDE_DATA_PARAM_CHANGE_SAMPLE_RATE    = 0x0004,
+    AV_SIDE_DATA_PARAM_CHANGE_DIMENSIONS     = 0x0008,
+};
+
 /**
  * Audio Video Frame.
  * New fields can be added to the end of AVFRAME with minor version

libavcodec/version.h

@@ -21,7 +21,7 @@
 #define AVCODEC_VERSION_H
 
 #define LIBAVCODEC_VERSION_MAJOR 53
-#define LIBAVCODEC_VERSION_MINOR 29
+#define LIBAVCODEC_VERSION_MINOR 30
 #define LIBAVCODEC_VERSION_MICRO  0
 
 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \