Merge commit 'a505c0d7373336a4cc5aa2022111c46bdd388b1f'

* commit 'a505c0d7373336a4cc5aa2022111c46bdd388b1f':
  rtp: Initial H.261 support

Conflicts:
	Changelog
	libavformat/rtpdec_h261.c
	libavformat/rtpenc_h261.c
	libavformat/sdp.c
	libavformat/version.h

See: 50a4d5cfc6749932347ee38c25b5040aea4b13a0
Merged-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 63 insertions, 18 deletions

diff --git a/libavformat/rtpenc_h261.c b/libavformat/rtpenc_h261.c
index 6f63703f0a..9930b71473 100644
--- a/libavformat/rtpenc_h261.c
+++ b/libavformat/rtpenc_h261.c
@@ -22,36 +22,81 @@
 #include "avformat.h"
 #include "rtpenc.h"
 
-void ff_rtp_send_h261(AVFormatContext *s1, const uint8_t *frame_buf, int frame_size)
+#define RTP_H261_HEADER_SIZE 4
+
+static const uint8_t *find_resync_marker_reverse(const uint8_t *restrict start,
+                                                 const uint8_t *restrict end)
+{
+    const uint8_t *p = end - 1;
+    start += 1; /* Make sure we never return the original start. */
+    for (; p > start; p--) {
+        if (p[0] == 0 && p[1] == 1)
+            return p;
+    }
+    return end;
+}
+
+void ff_rtp_send_h261(AVFormatContext *ctx, const uint8_t *frame_buf, int frame_size)
 {
-    RTPMuxContext *rtp_ctx = s1->priv_data;
-    int processed_frame_size;
+    int cur_frame_size;
     int last_packet_of_frame;
-    uint8_t *tmp_buf_ptr;
+    RTPMuxContext *rtp_ctx = ctx->priv_data;
 
     /* use the default 90 KHz time stamp */
     rtp_ctx->timestamp = rtp_ctx->cur_timestamp;
 
     /* continue as long as not all frame data is processed */
     while (frame_size > 0) {
-        tmp_buf_ptr = rtp_ctx->buf;
-        *tmp_buf_ptr++ = 1; /* V=1 */
-        *tmp_buf_ptr++ = 0;
-        *tmp_buf_ptr++ = 0;
-        *tmp_buf_ptr++ = 0;
-
-        processed_frame_size = FFMIN(rtp_ctx->max_payload_size - 4, frame_size);
+        /*
+         * encode the H.261 payload header according to section 4.1 of RFC 4587:
+         * (uses 4 bytes between RTP header and H.261 stream per packet)
+         *
+         *    0                   1                   2                   3
+         *    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+         *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+         *   |SBIT |EBIT |I|V| GOBN  |   MBAP  |  QUANT  |  HMVD   |  VMVD   |
+         *   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+         *
+         *      Start bit position (SBIT): 3 bits
+         *      End bit position (EBIT): 3 bits
+         *      INTRA-frame encoded data (I): 1 bit
+         *      Motion Vector flag (V): 1 bit
+         *      GOB number (GOBN): 4 bits
+         *      Macroblock address predictor (MBAP): 5 bits
+         *      Quantizer (QUANT): 5 bits
+         *      Horizontal motion vector data (HMVD): 5 bits
+         *      Vertical motion vector data (VMVD): 5 bits
+         */
+        rtp_ctx->buf[0] = 1; /* sbit=0, ebit=0, i=0, v=1 */
+        rtp_ctx->buf[1] = 0; /* gobn=0, mbap=0 */
+        rtp_ctx->buf[2] = 0; /* quant=0, hmvd=5 */
+        rtp_ctx->buf[3] = 0; /* vmvd=0 */
+        if (frame_size < 2 || frame_buf[0] != 0 || frame_buf[1] != 1) {
+            /* A full, correct fix for this would be to make the H261 encoder
+             * support inserting extra GOB headers (triggered by setting e.g.
+             * "-ps 1"), and including information about macroblock boundaries
+             * (such as for h263_rfc2190). */
+            av_log(ctx, AV_LOG_WARNING,
+                   "RTP/H261 packet not cut at a GOB boundary, not signaled correctly\n");
+        }
 
-        //XXX: parse the h.261 bitstream and improve frame splitting here
+        cur_frame_size = FFMIN(rtp_ctx->max_payload_size - RTP_H261_HEADER_SIZE, frame_size);
 
-        last_packet_of_frame = (processed_frame_size == frame_size);
+        /* look for a better place to split the frame into packets */
+        if (cur_frame_size < frame_size) {
+            const uint8_t *packet_end = find_resync_marker_reverse(frame_buf,
+                                                                   frame_buf + cur_frame_size);
+            cur_frame_size = packet_end - frame_buf;
+        }
 
-        memcpy(tmp_buf_ptr, frame_buf, processed_frame_size);
-        tmp_buf_ptr += processed_frame_size;
+        /* calculate the "marker" bit for the RTP header */
+        last_packet_of_frame = cur_frame_size == frame_size;
 
-        ff_rtp_send_data(s1, rtp_ctx->buf, tmp_buf_ptr - rtp_ctx->buf, last_packet_of_frame);
+        /* complete and send RTP packet */
+        memcpy(&rtp_ctx->buf[RTP_H261_HEADER_SIZE], frame_buf, cur_frame_size);
+        ff_rtp_send_data(ctx, rtp_ctx->buf, RTP_H261_HEADER_SIZE + cur_frame_size, last_packet_of_frame);
 
-        frame_buf += processed_frame_size;
-        frame_size -= processed_frame_size;
+        frame_buf  += cur_frame_size;
+        frame_size -= cur_frame_size;
     }
 }