317 lines
9.6 KiB
C
317 lines
9.6 KiB
C
/*
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* MPEG2 transport stream (aka DVB) demux
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* Copyright (c) 2002 Gerard Lantau.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "avformat.h"
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#define TS_FEC_PACKET_SIZE 204
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#define TS_PACKET_SIZE 188
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#define NB_PID_MAX 8192
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enum MpegTSState {
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MPEGTS_HEADER = 0,
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MPEGTS_PESHEADER_FILL,
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MPEGTS_PESHEADER_FLAGS,
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MPEGTS_PESHEADER_SIZE,
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MPEGTS_PESHEADER_READ,
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MPEGTS_PAYLOAD,
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MPEGTS_SKIP,
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};
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/* enough for PES header + length */
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#define MAX_HEADER_SIZE 6
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typedef struct MpegTSStream {
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int pid;
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enum MpegTSState state;
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int last_cc; /* last cc code (-1 if first packet) */
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/* used to get the format */
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int header_size;
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int payload_size;
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int pes_header_size;
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AVStream *st;
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unsigned char header[MAX_HEADER_SIZE];
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} MpegTSStream;
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typedef struct MpegTSContext {
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int raw_packet_size; /* raw packet size, including FEC if present */
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MpegTSStream *pids[NB_PID_MAX];
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} MpegTSContext;
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/* autodetect fec presence. Must have at least 1024 bytes */
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static int get_packet_size(const unsigned char *buf, int size)
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{
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int i;
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if (size < (TS_FEC_PACKET_SIZE * 5 + 1))
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return -1;
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for(i=0;i<5;i++) {
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if (buf[i * TS_PACKET_SIZE] != 0x47)
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goto try_fec;
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}
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return TS_PACKET_SIZE;
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try_fec:
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for(i=0;i<5;i++) {
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if (buf[i * TS_FEC_PACKET_SIZE] != 0x47)
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return -1;
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}
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return TS_FEC_PACKET_SIZE;
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}
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static int mpegts_probe(AVProbeData *p)
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{
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int size;
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size = get_packet_size(p->buf, p->buf_size);
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if (size < 0)
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return 0;
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return AVPROBE_SCORE_MAX;
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}
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static int mpegts_read_header(AVFormatContext *s,
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AVFormatParameters *ap)
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{
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MpegTSContext *ts = s->priv_data;
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ByteIOContext *pb = &s->pb;
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unsigned char buf[1024];
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int len;
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INT64 pos;
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/* read the first 1024 bytes to get packet size */
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pos = url_ftell(pb);
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len = get_buffer(pb, buf, sizeof(buf));
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if (len != sizeof(buf))
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goto fail;
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ts->raw_packet_size = get_packet_size(buf, sizeof(buf));
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if (ts->raw_packet_size <= 0)
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goto fail;
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/* go again to the start */
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url_fseek(pb, pos, SEEK_SET);
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return 0;
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fail:
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return -1;
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}
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/* return non zero if a packet could be constructed */
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static int mpegts_push_data(AVFormatContext *s, MpegTSStream *tss,
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AVPacket *pkt,
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const unsigned char *buf, int buf_size, int is_start)
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{
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AVStream *st;
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const unsigned char *p;
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int len, code, codec_type, codec_id;
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if (is_start) {
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tss->state = MPEGTS_HEADER;
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tss->header_size = 0;
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}
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p = buf;
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while (buf_size > 0) {
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len = buf_size;
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switch(tss->state) {
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case MPEGTS_HEADER:
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if (len > MAX_HEADER_SIZE - tss->header_size)
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len = MAX_HEADER_SIZE - tss->header_size;
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memcpy(tss->header, p, len);
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tss->header_size += len;
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p += len;
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buf_size -= len;
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if (tss->header_size == MAX_HEADER_SIZE) {
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/* we got all the PES or section header. We can now
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decide */
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#if 0
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av_hex_dump(tss->header, tss->header_size);
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#endif
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if (tss->header[0] == 0x00 && tss->header[1] == 0x00 &&
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tss->header[2] == 0x01) {
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/* it must be an mpeg2 PES stream */
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/* XXX: add AC3 support */
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code = tss->header[3] | 0x100;
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if (!((code >= 0x1c0 && code <= 0x1df) ||
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(code >= 0x1e0 && code <= 0x1ef)))
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goto skip;
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if (!tss->st) {
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/* allocate stream */
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if (code >= 0x1c0 && code <= 0x1df) {
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codec_type = CODEC_TYPE_AUDIO;
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codec_id = CODEC_ID_MP2;
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} else {
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codec_type = CODEC_TYPE_VIDEO;
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codec_id = CODEC_ID_MPEG1VIDEO;
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}
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st = av_new_stream(s, tss->pid);
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if (st) {
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st->priv_data = tss;
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st->codec.codec_type = codec_type;
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st->codec.codec_id = codec_id;
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tss->st = st;
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}
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}
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tss->state = MPEGTS_PESHEADER_FILL;
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tss->payload_size = (tss->header[4] << 8) | tss->header[5];
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if (tss->payload_size == 0)
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tss->payload_size = 65536;
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} else {
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/* otherwise, it should be a table */
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/* skip packet */
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skip:
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tss->state = MPEGTS_SKIP;
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continue;
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}
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}
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break;
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/**********************************************/
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/* PES packing parsing */
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case MPEGTS_PESHEADER_FILL:
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/* skip filling */
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code = *p++;
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buf_size--;
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tss->payload_size--;
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if (code != 0xff) {
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if ((code & 0xc0) != 0x80)
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goto skip;
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tss->state = MPEGTS_PESHEADER_FLAGS;
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}
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break;
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case MPEGTS_PESHEADER_FLAGS:
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code = *p++;
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buf_size--;
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tss->payload_size--;
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tss->state = MPEGTS_PESHEADER_SIZE;
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break;
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case MPEGTS_PESHEADER_SIZE:
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tss->pes_header_size = *p++;
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buf_size--;
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tss->payload_size--;
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tss->state = MPEGTS_PESHEADER_READ;
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break;
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case MPEGTS_PESHEADER_READ:
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/* currently we do nothing except skipping */
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if (len > tss->pes_header_size)
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len = tss->pes_header_size;
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p += len;
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buf_size -= len;
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tss->pes_header_size -= len;
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tss->payload_size -= len;
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if (tss->pes_header_size == 0)
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tss->state = MPEGTS_PAYLOAD;
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break;
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case MPEGTS_PAYLOAD:
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if (len > tss->payload_size)
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len = tss->payload_size;
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if (len > 0) {
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if (tss->st && av_new_packet(pkt, buf_size) == 0) {
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memcpy(pkt->data, p, buf_size);
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pkt->stream_index = tss->st->index;
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return 1;
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}
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tss->payload_size -= len;
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}
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buf_size = 0;
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break;
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case MPEGTS_SKIP:
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buf_size = 0;
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break;
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}
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}
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return 0;
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}
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static int mpegts_read_packet(AVFormatContext *s,
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AVPacket *pkt)
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{
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MpegTSContext *ts = s->priv_data;
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MpegTSStream *tss;
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ByteIOContext *pb = &s->pb;
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unsigned char packet[TS_FEC_PACKET_SIZE];
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int len, pid, cc, cc_ok, afc;
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const unsigned char *p;
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for(;;) {
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len = get_buffer(pb, packet, ts->raw_packet_size);
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if (len != ts->raw_packet_size)
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return AVERROR_IO;
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/* check paquet sync byte */
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/* XXX: accept to resync ? */
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if (packet[0] != 0x47)
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return AVERROR_INVALIDDATA;
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pid = ((packet[1] & 0x1f) << 8) | packet[2];
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tss = ts->pids[pid];
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if (tss == NULL) {
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/* if no pid found, then add a pid context */
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tss = av_mallocz(sizeof(MpegTSStream));
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if (!tss)
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continue;
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ts->pids[pid] = tss;
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tss->pid = pid;
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tss->last_cc = -1;
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// printf("new pid=0x%x\n", pid);
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}
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/* continuity check (currently not used) */
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cc = (packet[3] & 0xf);
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cc_ok = (tss->last_cc < 0) || ((((tss->last_cc + 1) & 0x0f) == cc));
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tss->last_cc = cc;
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/* skip adaptation field */
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afc = (packet[3] >> 4) & 3;
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p = packet + 4;
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if (afc == 0) /* reserved value */
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continue;
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if (afc == 2) /* adaptation field only */
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continue;
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if (afc == 3) {
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/* skip adapation field */
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p += p[0] + 1;
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}
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/* if past the end of packet, ignore */
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if (p >= packet + TS_PACKET_SIZE)
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continue;
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if (mpegts_push_data(s, tss, pkt, p, TS_PACKET_SIZE - (p - packet),
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packet[1] & 0x40))
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break;
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}
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return 0;
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}
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static int mpegts_read_close(AVFormatContext *s)
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{
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MpegTSContext *ts = s->priv_data;
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int i;
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for(i=0;i<NB_PID_MAX;i++)
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av_free(ts->pids[i]);
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return 0;
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}
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AVInputFormat mpegts_demux = {
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"mpegts",
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"MPEG2 transport stream format",
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sizeof(MpegTSContext),
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mpegts_probe,
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mpegts_read_header,
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mpegts_read_packet,
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mpegts_read_close,
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flags: AVFMT_NOHEADER | AVFMT_SHOW_IDS,
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};
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int mpegts_init(void)
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{
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av_register_input_format(&mpegts_demux);
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return 0;
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}
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