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ffmpeg/libavformat/mpegts.c

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/*
* MPEG2 transport stream (aka DVB) demux
* Copyright (c) 2002 Fabrice Bellard.
*
* This library 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 of the License, or (at your option) any later version.
*
* This library 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 this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "avformat.h"
#define TS_FEC_PACKET_SIZE 204
#define TS_PACKET_SIZE 188
#define NB_PID_MAX 8192
enum MpegTSState {
MPEGTS_HEADER = 0,
MPEGTS_PESHEADER_FILL,
MPEGTS_PESHEADER_FLAGS,
MPEGTS_PESHEADER_SIZE,
MPEGTS_PESHEADER_READ,
MPEGTS_PAYLOAD,
MPEGTS_SKIP,
};
/* enough for PES header + length */
#define MAX_HEADER_SIZE 6
typedef struct MpegTSStream {
int pid;
enum MpegTSState state;
int last_cc; /* last cc code (-1 if first packet) */
/* used to get the format */
int header_size;
int payload_size;
int pes_header_size;
AVStream *st;
unsigned char header[MAX_HEADER_SIZE];
} MpegTSStream;
typedef struct MpegTSContext {
int raw_packet_size; /* raw packet size, including FEC if present */
MpegTSStream *pids[NB_PID_MAX];
} MpegTSContext;
/* autodetect fec presence. Must have at least 1024 bytes */
static int get_packet_size(const unsigned char *buf, int size)
{
int i;
if (size < (TS_FEC_PACKET_SIZE * 5 + 1))
return -1;
for(i=0;i<5;i++) {
if (buf[i * TS_PACKET_SIZE] != 0x47)
goto try_fec;
}
return TS_PACKET_SIZE;
try_fec:
for(i=0;i<5;i++) {
if (buf[i * TS_FEC_PACKET_SIZE] != 0x47)
return -1;
}
return TS_FEC_PACKET_SIZE;
}
static int mpegts_probe(AVProbeData *p)
{
int size;
size = get_packet_size(p->buf, p->buf_size);
if (size < 0)
return 0;
return AVPROBE_SCORE_MAX;
}
static int mpegts_read_header(AVFormatContext *s,
AVFormatParameters *ap)
{
MpegTSContext *ts = s->priv_data;
ByteIOContext *pb = &s->pb;
unsigned char buf[1024];
int len;
INT64 pos;
/* read the first 1024 bytes to get packet size */
pos = url_ftell(pb);
len = get_buffer(pb, buf, sizeof(buf));
if (len != sizeof(buf))
goto fail;
ts->raw_packet_size = get_packet_size(buf, sizeof(buf));
if (ts->raw_packet_size <= 0)
goto fail;
/* go again to the start */
url_fseek(pb, pos, SEEK_SET);
return 0;
fail:
return -1;
}
/* return non zero if a packet could be constructed */
static int mpegts_push_data(AVFormatContext *s, MpegTSStream *tss,
AVPacket *pkt,
const unsigned char *buf, int buf_size, int is_start)
{
AVStream *st;
const unsigned char *p;
int len, code, codec_type, codec_id;
if (is_start) {
tss->state = MPEGTS_HEADER;
tss->header_size = 0;
}
p = buf;
while (buf_size > 0) {
len = buf_size;
switch(tss->state) {
case MPEGTS_HEADER:
if (len > MAX_HEADER_SIZE - tss->header_size)
len = MAX_HEADER_SIZE - tss->header_size;
memcpy(tss->header, p, len);
tss->header_size += len;
p += len;
buf_size -= len;
if (tss->header_size == MAX_HEADER_SIZE) {
/* we got all the PES or section header. We can now
decide */
#if 0
av_hex_dump(tss->header, tss->header_size);
#endif
if (tss->header[0] == 0x00 && tss->header[1] == 0x00 &&
tss->header[2] == 0x01) {
/* it must be an mpeg2 PES stream */
/* XXX: add AC3 support */
code = tss->header[3] | 0x100;
if (!((code >= 0x1c0 && code <= 0x1df) ||
(code >= 0x1e0 && code <= 0x1ef)))
goto skip;
if (!tss->st) {
/* allocate stream */
if (code >= 0x1c0 && code <= 0x1df) {
codec_type = CODEC_TYPE_AUDIO;
codec_id = CODEC_ID_MP2;
} else {
codec_type = CODEC_TYPE_VIDEO;
codec_id = CODEC_ID_MPEG1VIDEO;
}
st = av_new_stream(s, tss->pid);
if (st) {
st->priv_data = tss;
st->codec.codec_type = codec_type;
st->codec.codec_id = codec_id;
tss->st = st;
}
}
tss->state = MPEGTS_PESHEADER_FILL;
tss->payload_size = (tss->header[4] << 8) | tss->header[5];
if (tss->payload_size == 0)
tss->payload_size = 65536;
} else {
/* otherwise, it should be a table */
/* skip packet */
skip:
tss->state = MPEGTS_SKIP;
continue;
}
}
break;
/**********************************************/
/* PES packing parsing */
case MPEGTS_PESHEADER_FILL:
/* skip filling */
code = *p++;
buf_size--;
tss->payload_size--;
if (code != 0xff) {
if ((code & 0xc0) != 0x80)
goto skip;
tss->state = MPEGTS_PESHEADER_FLAGS;
}
break;
case MPEGTS_PESHEADER_FLAGS:
code = *p++;
buf_size--;
tss->payload_size--;
tss->state = MPEGTS_PESHEADER_SIZE;
break;
case MPEGTS_PESHEADER_SIZE:
tss->pes_header_size = *p++;
buf_size--;
tss->payload_size--;
tss->state = MPEGTS_PESHEADER_READ;
break;
case MPEGTS_PESHEADER_READ:
/* currently we do nothing except skipping */
if (len > tss->pes_header_size)
len = tss->pes_header_size;
p += len;
buf_size -= len;
tss->pes_header_size -= len;
tss->payload_size -= len;
if (tss->pes_header_size == 0)
tss->state = MPEGTS_PAYLOAD;
break;
case MPEGTS_PAYLOAD:
if (len > tss->payload_size)
len = tss->payload_size;
if (len > 0) {
if (tss->st && av_new_packet(pkt, buf_size) == 0) {
memcpy(pkt->data, p, buf_size);
pkt->stream_index = tss->st->index;
return 1;
}
tss->payload_size -= len;
}
buf_size = 0;
break;
case MPEGTS_SKIP:
buf_size = 0;
break;
}
}
return 0;
}
static int mpegts_read_packet(AVFormatContext *s,
AVPacket *pkt)
{
MpegTSContext *ts = s->priv_data;
MpegTSStream *tss;
ByteIOContext *pb = &s->pb;
unsigned char packet[TS_FEC_PACKET_SIZE];
int len, pid, cc, cc_ok, afc;
const unsigned char *p;
for(;;) {
len = get_buffer(pb, packet, ts->raw_packet_size);
if (len != ts->raw_packet_size)
return AVERROR_IO;
/* check paquet sync byte */
/* XXX: accept to resync ? */
if (packet[0] != 0x47)
return AVERROR_INVALIDDATA;
pid = ((packet[1] & 0x1f) << 8) | packet[2];
tss = ts->pids[pid];
if (tss == NULL) {
/* if no pid found, then add a pid context */
tss = av_mallocz(sizeof(MpegTSStream));
if (!tss)
continue;
ts->pids[pid] = tss;
tss->pid = pid;
tss->last_cc = -1;
// printf("new pid=0x%x\n", pid);
}
/* continuity check (currently not used) */
cc = (packet[3] & 0xf);
cc_ok = (tss->last_cc < 0) || ((((tss->last_cc + 1) & 0x0f) == cc));
tss->last_cc = cc;
/* skip adaptation field */
afc = (packet[3] >> 4) & 3;
p = packet + 4;
if (afc == 0) /* reserved value */
continue;
if (afc == 2) /* adaptation field only */
continue;
if (afc == 3) {
/* skip adapation field */
p += p[0] + 1;
}
/* if past the end of packet, ignore */
if (p >= packet + TS_PACKET_SIZE)
continue;
if (mpegts_push_data(s, tss, pkt, p, TS_PACKET_SIZE - (p - packet),
packet[1] & 0x40))
break;
}
return 0;
}
static int mpegts_read_close(AVFormatContext *s)
{
MpegTSContext *ts = s->priv_data;
int i;
for(i=0;i<NB_PID_MAX;i++)
av_free(ts->pids[i]);
return 0;
}
AVInputFormat mpegts_demux = {
"mpegts",
"MPEG2 transport stream format",
sizeof(MpegTSContext),
mpegts_probe,
mpegts_read_header,
mpegts_read_packet,
mpegts_read_close,
.flags = AVFMT_NOHEADER | AVFMT_SHOW_IDS,
};
int mpegts_init(void)
{
av_register_input_format(&mpegts_demux);
return 0;
}
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