lavc: Deprecate avctx.rtp_callback field

This function returns the encoded data of a frame, one slice at a time
directly when that slice is encoded, instead of waiting for the full
frame to be done. However this field has a debatable usefulness, since
it looks like it is just a convoluted way to get data at lowest
possible latency, or a somewhat hacky way to store h263 in RFC-2190
rtp encapsulation.

Moreover when multi-threading is enabled (which is by default) the order
of returned slices is not deterministic at all, making the use of this
function not reliable at all (or at the very least, more complicated
than it should be).

So, for the reasons stated above, and being used by only a single encoder
family (mpegvideo), this field is deemed unnecessary, overcomplicated,
and not really belonging to libavcodec. Libavformat features a complete
implementation of RFC-2190, for any other case.

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
index 57dce366ce..e888952d4d 100644
--- a/libavcodec/avcodec.h
+++ b/libavcodec/avcodec.h
@@ -2372,13 +2372,19 @@ typedef struct AVCodecContext {
      */
     int64_t timecode_frame_start;
 
+#if FF_API_RTP_CALLBACK
+    /**
+     * @deprecated unused
+     */
     /* The RTP callback: This function is called    */
     /* every time the encoder has a packet to send. */
     /* It depends on the encoder if the data starts */
     /* with a Start Code (it should). H.263 does.   */
     /* mb_nb contains the number of macroblocks     */
     /* encoded in the RTP payload.                  */
+    attribute_deprecated
     void (*rtp_callback)(struct AVCodecContext *avctx, void *data, int size, int mb_nb);
+#endif
 
     int rtp_payload_size;   /* The size of the RTP payload: the coder will  */
                             /* do its best to deliver a chunk with size     */