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/*
* RTP packetization for H.263 video
* Copyright (c) 2012 Martin Storsjo
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avformat.h"
#include "rtpenc.h"
#include "libavcodec/put_bits.h"
#include "libavcodec/get_bits.h"
struct H263Info {
int src;
int i;
int u;
int s;
int a;
int pb;
int tr;
};
static void send_mode_a(AVFormatContext *s1, const struct H263Info *info,
const uint8_t *buf, int len, int m)
{
RTPMuxContext *s = s1->priv_data;
PutBitContext pb;
init_put_bits(&pb, s->buf, 32);
put_bits(&pb, 1, 0); /* F - 0, mode A */
put_bits(&pb, 1, 0); /* P - 0, normal I/P */
put_bits(&pb, 3, 0); /* SBIT - 0 bits */
put_bits(&pb, 3, 0); /* EBIT - 0 bits */
put_bits(&pb, 3, info->src); /* SRC - source format */
put_bits(&pb, 1, info->i); /* I - inter/intra */
put_bits(&pb, 1, info->u); /* U - unrestricted motion vector */
put_bits(&pb, 1, info->s); /* S - syntax-baesd arithmetic coding */
put_bits(&pb, 1, info->a); /* A - advanced prediction */
put_bits(&pb, 4, 0); /* R - reserved */
put_bits(&pb, 2, 0); /* DBQ - 0 */
put_bits(&pb, 3, 0); /* TRB - 0 */
put_bits(&pb, 8, info->tr); /* TR */
flush_put_bits(&pb);
memcpy(s->buf + 4, buf, len);
ff_rtp_send_data(s1, s->buf, len + 4, m);
}
void ff_rtp_send_h263_rfc2190(AVFormatContext *s1, const uint8_t *buf, int size)
{
RTPMuxContext *s = s1->priv_data;
int len;
GetBitContext gb;
struct H263Info info = { 0 };
s->timestamp = s->cur_timestamp;
init_get_bits(&gb, buf, size*8);
if (get_bits(&gb, 22) == 0x20) { /* Picture Start Code */
info.tr = get_bits(&gb, 8);
skip_bits(&gb, 2); /* PTYPE start, H261 disambiguation */
skip_bits(&gb, 3); /* Split screen, document camera, freeze picture release */
info.src = get_bits(&gb, 3);
info.i = get_bits(&gb, 1);
info.u = get_bits(&gb, 1);
info.s = get_bits(&gb, 1);
info.a = get_bits(&gb, 1);
info.pb = get_bits(&gb, 1);
}
while (size > 0) {
len = FFMIN(s->max_payload_size - 4, size);
/* Look for a better place to split the frame into packets. */
if (len < size) {
const uint8_t *end = ff_h263_find_resync_marker_reverse(buf,
buf + len);
len = end - buf;
if (len == s->max_payload_size - 4)
av_log(s1, AV_LOG_WARNING,
"No GOB boundary found within MTU size, splitting at "
"a random boundary\n");
}
send_mode_a(s1, &info, buf, len, len == size);
buf += len;
size -= len;
}
}
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