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