avcodec/cbs_sei: Use RefStruct API for SEI messages

The SEI message code uses the AVBuffer API for its SEI messages
and contained buffers (like the extension buffer for HEVC
or the user data (un)registered payload buffers).

Contrary to the ordinary CBS code (where some of these
contained buffer references are actually references
to the provided AVPacket's data so that one can't replace
them with the RefStruct API), the CBS SEI code never uses
outside buffers at all and can therefore be switched entirely
to the RefStruct API. This avoids the overhead inherent
in the AVBuffer API (namely the separate allocations etc.).

Notice that the refcounting here is actually currently unused;
the refcounts are always one (or zero in case of no refcounting);
its only advantage is the flexibility provided by custom
free functions.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

1 files changed, 16 insertions, 3 deletions

diff --git a/libavcodec/cbs_h2645.c b/libavcodec/cbs_h2645.c
index cce3f31d4f..615a7cf5ec 100644
--- a/libavcodec/cbs_h2645.c
+++ b/libavcodec/cbs_h2645.c
@@ -331,18 +331,31 @@ static int cbs_h2645_read_more_rbsp_data(GetBitContext *gbc)
 #define bit_position(rw)   (get_bits_count(rw))
 #define byte_alignment(rw) (get_bits_count(rw) % 8)
 
+/* The CBS SEI code uses the refstruct API for the allocation
+ * of its child buffers. */
 #define allocate(name, size) do { \
-        name ## _ref = av_buffer_allocz(size + \
+        name  = ff_refstruct_allocz(size + \
                                         AV_INPUT_BUFFER_PADDING_SIZE); \
-        if (!name ## _ref) \
+        if (!name) \
             return AVERROR(ENOMEM); \
-        name = name ## _ref->data; \
     } while (0)
 
 #define FUNC(name) FUNC_SEI(name)
 #include "cbs_sei_syntax_template.c"
 #undef FUNC
 
+#undef allocate
+
+/* The other code uses the refstruct API for the allocation
+ * of its child buffers. */
+#define allocate(name, size) do { \
+        name ## _ref = av_buffer_allocz(size + \
+                                        AV_INPUT_BUFFER_PADDING_SIZE); \
+        if (!name ## _ref) \
+            return AVERROR(ENOMEM); \
+        name = name ## _ref->data; \
+    } while (0)
+
 #define FUNC(name) FUNC_H264(name)
 #include "cbs_h264_syntax_template.c"
 #undef FUNC