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libavformat/rtpenc_h263.c

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00001 /*
00002  * RTP packetization for H.263 video
00003  * Copyright (c) 2009 Luca Abeni
00004  * Copyright (c) 2009 Martin Storsjo
00005  *
00006  * This file is part of FFmpeg.
00007  *
00008  * FFmpeg is free software; you can redistribute it and/or
00009  * modify it under the terms of the GNU Lesser General Public
00010  * License as published by the Free Software Foundation; either
00011  * version 2.1 of the License, or (at your option) any later version.
00012  *
00013  * FFmpeg is distributed in the hope that it will be useful,
00014  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00015  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00016  * Lesser General Public License for more details.
00017  *
00018  * You should have received a copy of the GNU Lesser General Public
00019  * License along with FFmpeg; if not, write to the Free Software
00020  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00021  */
00022 
00023 #include "avformat.h"
00024 #include "rtpenc.h"
00025 
00026 static const uint8_t *find_resync_marker_reverse(const uint8_t *restrict start,
00027                                                  const uint8_t *restrict end)
00028 {
00029     const uint8_t *p = end - 1;
00030     start += 1; /* Make sure we never return the original start. */
00031     for (; p > start; p -= 2) {
00032         if (!*p) {
00033             if      (!p[ 1] && p[2]) return p;
00034             else if (!p[-1] && p[1]) return p - 1;
00035         }
00036     }
00037     return end;
00038 }
00039 
00043 void ff_rtp_send_h263(AVFormatContext *s1, const uint8_t *buf1, int size)
00044 {
00045     RTPMuxContext *s = s1->priv_data;
00046     int len, max_packet_size;
00047     uint8_t *q;
00048 
00049     max_packet_size = s->max_payload_size;
00050 
00051     while (size > 0) {
00052         q = s->buf;
00053         if (size >= 2 && (buf1[0] == 0) && (buf1[1] == 0)) {
00054             *q++ = 0x04;
00055             buf1 += 2;
00056             size -= 2;
00057         } else {
00058             *q++ = 0;
00059         }
00060         *q++ = 0;
00061 
00062         len = FFMIN(max_packet_size - 2, size);
00063 
00064         /* Look for a better place to split the frame into packets. */
00065         if (len < size) {
00066             const uint8_t *end = find_resync_marker_reverse(buf1, buf1 + len);
00067             len = end - buf1;
00068         }
00069 
00070         memcpy(q, buf1, len);
00071         q += len;
00072 
00073         /* 90 KHz time stamp */
00074         s->timestamp = s->cur_timestamp;
00075         ff_rtp_send_data(s1, s->buf, q - s->buf, (len == size));
00076 
00077         buf1 += len;
00078         size -= len;
00079     }
00080 }

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