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ffmpeg / libavformat / rtpenc_h263.c @ 34056cbb

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/*
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 * RTP packetization for H.263 video
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 * Copyright (c) 2009 Luca Abeni
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 * Copyright (c) 2009 Martin Storsjo
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg 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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 * FFmpeg 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 FFmpeg; 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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static const uint8_t *find_resync_marker_reverse(const uint8_t *restrict start,
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                                                 const uint8_t *restrict end)
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{
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    const uint8_t *p = end - 1;
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    start += 1; /* Make sure we never return the original start. */
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    for (; p > start; p -= 2) {
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        if (!*p) {
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            if      (!p[ 1] && p[2]) return p;
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            else if (!p[-1] && p[1]) return p - 1;
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        }
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    }
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    return end;
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}
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/**
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 * Packetize H.263 frames into RTP packets according to RFC 4629
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 */
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void ff_rtp_send_h263(AVFormatContext *s1, const uint8_t *buf1, int size)
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{
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    RTPMuxContext *s = s1->priv_data;
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    int len, max_packet_size;
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    uint8_t *q;
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    max_packet_size = s->max_payload_size;
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    while (size > 0) {
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        q = s->buf;
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        if (size >= 2 && (buf1[0] == 0) && (buf1[1] == 0)) {
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            *q++ = 0x04;
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            buf1 += 2;
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            size -= 2;
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        } else {
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            *q++ = 0;
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        }
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        *q++ = 0;
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        len = FFMIN(max_packet_size - 2, 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 = find_resync_marker_reverse(buf1, buf1 + len);
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            len = end - buf1;
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        }
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        memcpy(q, buf1, len);
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        q += len;
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        /* 90 KHz time stamp */
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        s->timestamp = s->cur_timestamp;
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        ff_rtp_send_data(s1, s->buf, q - s->buf, (len == size));
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        buf1 += len;
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        size -= len;
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    }
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}