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FFmpeg/libavformat/mpeg.c

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/*
* MPEG1/2 demuxer
* Copyright (c) 2000, 2001, 2002 Fabrice Bellard
*
* This file is part of Libav.
*
* Libav 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 2.1 of the License, or (at your option) any later version.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "avformat.h"
#include "internal.h"
#include "mpeg.h"
#undef NDEBUG
#include <assert.h>
/*********************************************/
/* demux code */
#define MAX_SYNC_SIZE 100000
static int check_pes(uint8_t *p, uint8_t *end)
{
int pes1;
int pes2 = (p[3] & 0xC0) == 0x80 &&
(p[4] & 0xC0) != 0x40 &&
((p[4] & 0xC0) == 0x00 ||
(p[4] & 0xC0) >> 2 == (p[6] & 0xF0));
for (p += 3; p < end && *p == 0xFF; p++) ;
if ((*p & 0xC0) == 0x40)
p += 2;
if ((*p & 0xF0) == 0x20)
pes1 = p[0] & p[2] & p[4] & 1;
else if ((*p & 0xF0) == 0x30)
pes1 = p[0] & p[2] & p[4] & p[5] & p[7] & p[9] & 1;
else
pes1 = *p == 0x0F;
return pes1 || pes2;
}
static int check_pack_header(const uint8_t *buf)
{
return (buf[1] & 0xC0) == 0x40 || (buf[1] & 0xF0) == 0x20;
}
static int mpegps_probe(AVProbeData *p)
{
uint32_t code = -1;
int i;
int sys = 0, pspack = 0, priv1 = 0, vid = 0;
int audio = 0, invalid = 0, score = 0;
for (i = 0; i < p->buf_size; i++) {
code = (code << 8) + p->buf[i];
if ((code & 0xffffff00) == 0x100) {
int len = p->buf[i + 1] << 8 | p->buf[i + 2];
int pes = check_pes(p->buf + i, p->buf + p->buf_size);
int pack = check_pack_header(p->buf + i);
if (code == SYSTEM_HEADER_START_CODE)
sys++;
else if (code == PACK_START_CODE && pack)
pspack++;
else if ((code & 0xf0) == VIDEO_ID && pes)
vid++;
// skip pes payload to avoid start code emulation for private
// and audio streams
else if ((code & 0xe0) == AUDIO_ID && pes) {
audio++;
i += len;
} else if (code == PRIVATE_STREAM_1 && pes) {
priv1++;
i += len;
} else if ((code & 0xf0) == VIDEO_ID && !pes)
invalid++;
else if ((code & 0xe0) == AUDIO_ID && !pes)
invalid++;
else if (code == PRIVATE_STREAM_1 && !pes)
invalid++;
}
}
if (vid + audio > invalid) /* invalid VDR files nd short PES streams */
score = AVPROBE_SCORE_EXTENSION / 2;
if (sys > invalid && sys * 9 <= pspack * 10)
return pspack > 2 ? AVPROBE_SCORE_EXTENSION + 2
: AVPROBE_SCORE_EXTENSION / 2; // 1 more than .mpg
if (pspack > invalid && (priv1 + vid + audio) * 10 >= pspack * 9)
return pspack > 2 ? AVPROBE_SCORE_EXTENSION + 2
: AVPROBE_SCORE_EXTENSION / 2; // 1 more than .mpg
if ((!!vid ^ !!audio) && (audio > 4 || vid > 1) && !sys &&
!pspack && p->buf_size > 2048 && vid + audio > invalid) /* PES stream */
return (audio > 12 || vid > 3) ? AVPROBE_SCORE_EXTENSION + 2
: AVPROBE_SCORE_EXTENSION / 2;
// 02-Penguin.flac has sys:0 priv1:0 pspack:0 vid:0 audio:1
// mp3_misidentified_2.mp3 has sys:0 priv1:0 pspack:0 vid:0 audio:6
return score;
}
typedef struct MpegDemuxContext {
int32_t header_state;
unsigned char psm_es_type[256];
int sofdec;
} MpegDemuxContext;
static int mpegps_read_header(AVFormatContext *s)
{
MpegDemuxContext *m = s->priv_data;
const char *sofdec = "Sofdec";
int v, i = 0;
m->header_state = 0xff;
s->ctx_flags |= AVFMTCTX_NOHEADER;
m->sofdec = -1;
do {
v = avio_r8(s->pb);
m->header_state = m->header_state << 8 | v;
m->sofdec++;
} while (v == sofdec[i] && i++ < 6);
m->sofdec = (m->sofdec == 6) ? 1 : 0;
/* no need to do more */
return 0;
}
static int64_t get_pts(AVIOContext *pb, int c)
{
uint8_t buf[5];
buf[0] = c < 0 ? avio_r8(pb) : c;
avio_read(pb, buf + 1, 4);
return ff_parse_pes_pts(buf);
}
static int find_next_start_code(AVIOContext *pb, int *size_ptr,
int32_t *header_state)
{
unsigned int state, v;
int val, n;
state = *header_state;
n = *size_ptr;
while (n > 0) {
if (pb->eof_reached)
break;
v = avio_r8(pb);
n--;
if (state == 0x000001) {
state = ((state << 8) | v) & 0xffffff;
val = state;
goto found;
}
state = ((state << 8) | v) & 0xffffff;
}
val = -1;
found:
*header_state = state;
*size_ptr = n;
return val;
}
/**
* Extract stream types from a program stream map
* According to ISO/IEC 13818-1 ('MPEG-2 Systems') table 2-35
*
* @return number of bytes occupied by PSM in the bitstream
*/
static long mpegps_psm_parse(MpegDemuxContext *m, AVIOContext *pb)
{
int psm_length, ps_info_length, es_map_length;
psm_length = avio_rb16(pb);
avio_r8(pb);
avio_r8(pb);
ps_info_length = avio_rb16(pb);
/* skip program_stream_info */
avio_skip(pb, ps_info_length);
es_map_length = avio_rb16(pb);
/* at least one es available? */
while (es_map_length >= 4) {
unsigned char type = avio_r8(pb);
unsigned char es_id = avio_r8(pb);
uint16_t es_info_length = avio_rb16(pb);
/* remember mapping from stream id to stream type */
m->psm_es_type[es_id] = type;
/* skip program_stream_info */
avio_skip(pb, es_info_length);
es_map_length -= 4 + es_info_length;
}
avio_rb32(pb); /* crc32 */
return 2 + psm_length;
}
/* read the next PES header. Return its position in ppos
* (if not NULL), and its start code, pts and dts.
*/
static int mpegps_read_pes_header(AVFormatContext *s,
int64_t *ppos, int *pstart_code,
int64_t *ppts, int64_t *pdts)
{
MpegDemuxContext *m = s->priv_data;
int len, size, startcode, c, flags, header_len;
int pes_ext, ext2_len, id_ext, skip;
int64_t pts, dts;
int64_t last_sync = avio_tell(s->pb);
error_redo:
avio_seek(s->pb, last_sync, SEEK_SET);
redo:
/* next start code (should be immediately after) */
m->header_state = 0xff;
size = MAX_SYNC_SIZE;
startcode = find_next_start_code(s->pb, &size, &m->header_state);
last_sync = avio_tell(s->pb);
if (startcode < 0) {
if (s->pb->eof_reached)
return AVERROR_EOF;
// FIXME we should remember header_state
return AVERROR(EAGAIN);
}
if (startcode == PACK_START_CODE)
goto redo;
if (startcode == SYSTEM_HEADER_START_CODE)
goto redo;
if (startcode == PADDING_STREAM) {
avio_skip(s->pb, avio_rb16(s->pb));
goto redo;
}
if (startcode == PRIVATE_STREAM_2) {
len = avio_rb16(s->pb);
if (!m->sofdec) {
while (len-- >= 6) {
if (avio_r8(s->pb) == 'S') {
uint8_t buf[5];
avio_read(s->pb, buf, sizeof(buf));
m->sofdec = !memcmp(buf, "ofdec", 5);
len -= sizeof(buf);
break;
}
}
m->sofdec -= !m->sofdec;
}
avio_skip(s->pb, len);
goto redo;
}
if (startcode == PROGRAM_STREAM_MAP) {
mpegps_psm_parse(m, s->pb);
goto redo;
}
/* find matching stream */
if (!((startcode >= 0x1c0 && startcode <= 0x1df) ||
(startcode >= 0x1e0 && startcode <= 0x1ef) ||
(startcode == 0x1bd) || (startcode == 0x1fd)))
goto redo;
if (ppos) {
*ppos = avio_tell(s->pb) - 4;
}
len = avio_rb16(s->pb);
pts =
dts = AV_NOPTS_VALUE;
/* stuffing */
for (;;) {
if (len < 1)
goto error_redo;
c = avio_r8(s->pb);
len--;
/* XXX: for mpeg1, should test only bit 7 */
if (c != 0xff)
break;
}
if ((c & 0xc0) == 0x40) {
/* buffer scale & size */
avio_r8(s->pb);
c = avio_r8(s->pb);
len -= 2;
}
if ((c & 0xe0) == 0x20) {
dts =
pts = get_pts(s->pb, c);
len -= 4;
if (c & 0x10) {
dts = get_pts(s->pb, -1);
len -= 5;
}
} else if ((c & 0xc0) == 0x80) {
/* mpeg 2 PES */
flags = avio_r8(s->pb);
header_len = avio_r8(s->pb);
len -= 2;
if (header_len > len)
goto error_redo;
len -= header_len;
if (flags & 0x80) {
dts = pts = get_pts(s->pb, -1);
header_len -= 5;
if (flags & 0x40) {
dts = get_pts(s->pb, -1);
header_len -= 5;
}
}
if (flags & 0x3f && header_len == 0) {
flags &= 0xC0;
av_log(s, AV_LOG_WARNING, "Further flags set but no bytes left\n");
}
if (flags & 0x01) { /* PES extension */
pes_ext = avio_r8(s->pb);
header_len--;
/* Skip PES private data, program packet sequence counter
* and P-STD buffer */
skip = (pes_ext >> 4) & 0xb;
skip += skip & 0x9;
if (pes_ext & 0x40 || skip > header_len) {
av_log(s, AV_LOG_WARNING, "pes_ext %X is invalid\n", pes_ext);
pes_ext = skip = 0;
}
avio_skip(s->pb, skip);
header_len -= skip;
if (pes_ext & 0x01) { /* PES extension 2 */
ext2_len = avio_r8(s->pb);
header_len--;
if ((ext2_len & 0x7f) > 0) {
id_ext = avio_r8(s->pb);
if ((id_ext & 0x80) == 0)
startcode = ((startcode & 0xff) << 8) | id_ext;
header_len--;
}
}
}
if (header_len < 0)
goto error_redo;
avio_skip(s->pb, header_len);
} else if (c != 0xf)
goto redo;
if (startcode == PRIVATE_STREAM_1 && !m->psm_es_type[startcode & 0xff]) {
startcode = avio_r8(s->pb);
len--;
if (startcode >= 0x80 && startcode <= 0xcf) {
/* audio: skip header */
avio_r8(s->pb);
avio_r8(s->pb);
avio_r8(s->pb);
len -= 3;
if (startcode >= 0xb0 && startcode <= 0xbf) {
/* MLP/TrueHD audio has a 4-byte header */
avio_r8(s->pb);
len--;
}
}
}
if (len < 0)
goto error_redo;
if (dts != AV_NOPTS_VALUE && ppos) {
int i;
for (i = 0; i < s->nb_streams; i++) {
if (startcode == s->streams[i]->id &&
s->pb->seekable /* index useless on streams anyway */) {
ff_reduce_index(s, i);
av_add_index_entry(s->streams[i], *ppos, dts, 0, 0,
AVINDEX_KEYFRAME /* FIXME keyframe? */);
}
}
}
*pstart_code = startcode;
*ppts = pts;
*pdts = dts;
return len;
}
static int mpegps_read_packet(AVFormatContext *s,
AVPacket *pkt)
{
MpegDemuxContext *m = s->priv_data;
AVStream *st;
int len, startcode, i, es_type, ret;
enum AVCodecID codec_id = AV_CODEC_ID_NONE;
enum AVMediaType type;
int64_t pts, dts, dummy_pos; // dummy_pos is needed for the index building to work
uint8_t av_uninit(dvdaudio_substream_type);
redo:
len = mpegps_read_pes_header(s, &dummy_pos, &startcode, &pts, &dts);
if (len < 0)
return len;
if (startcode == 0x1bd) {
dvdaudio_substream_type = avio_r8(s->pb);
avio_skip(s->pb, 3);
len -= 4;
}
/* now find stream */
for (i = 0; i < s->nb_streams; i++) {
st = s->streams[i];
if (st->id == startcode)
goto found;
}
es_type = m->psm_es_type[startcode & 0xff];
if (es_type > 0 && es_type != STREAM_TYPE_PRIVATE_DATA) {
if (es_type == STREAM_TYPE_VIDEO_MPEG1) {
codec_id = AV_CODEC_ID_MPEG2VIDEO;
type = AVMEDIA_TYPE_VIDEO;
} else if (es_type == STREAM_TYPE_VIDEO_MPEG2) {
codec_id = AV_CODEC_ID_MPEG2VIDEO;
type = AVMEDIA_TYPE_VIDEO;
} else if (es_type == STREAM_TYPE_AUDIO_MPEG1 ||
es_type == STREAM_TYPE_AUDIO_MPEG2) {
codec_id = AV_CODEC_ID_MP3;
type = AVMEDIA_TYPE_AUDIO;
} else if (es_type == STREAM_TYPE_AUDIO_AAC) {
codec_id = AV_CODEC_ID_AAC;
type = AVMEDIA_TYPE_AUDIO;
} else if (es_type == STREAM_TYPE_VIDEO_MPEG4) {
codec_id = AV_CODEC_ID_MPEG4;
type = AVMEDIA_TYPE_VIDEO;
} else if (es_type == STREAM_TYPE_VIDEO_H264) {
codec_id = AV_CODEC_ID_H264;
type = AVMEDIA_TYPE_VIDEO;
} else if (es_type == STREAM_TYPE_AUDIO_AC3) {
codec_id = AV_CODEC_ID_AC3;
type = AVMEDIA_TYPE_AUDIO;
} else {
goto skip;
}
} else if (startcode >= 0x1e0 && startcode <= 0x1ef) {
static const unsigned char avs_seqh[4] = { 0, 0, 1, 0xb0 };
unsigned char buf[8];
avio_read(s->pb, buf, 8);
avio_seek(s->pb, -8, SEEK_CUR);
if (!memcmp(buf, avs_seqh, 4) && (buf[6] != 0 || buf[7] != 1))
codec_id = AV_CODEC_ID_CAVS;
else
codec_id = AV_CODEC_ID_PROBE;
type = AVMEDIA_TYPE_VIDEO;
} else if (startcode >= 0x1c0 && startcode <= 0x1df) {
type = AVMEDIA_TYPE_AUDIO;
codec_id = m->sofdec > 0 ? AV_CODEC_ID_ADPCM_ADX : AV_CODEC_ID_MP2;
} else if (startcode >= 0x80 && startcode <= 0x87) {
type = AVMEDIA_TYPE_AUDIO;
codec_id = AV_CODEC_ID_AC3;
} else if ((startcode >= 0x88 && startcode <= 0x8f) ||
(startcode >= 0x98 && startcode <= 0x9f)) {
/* 0x90 - 0x97 is reserved for SDDS in DVD specs */
type = AVMEDIA_TYPE_AUDIO;
codec_id = AV_CODEC_ID_DTS;
} else if (startcode >= 0xa0 && startcode <= 0xaf) {
type = AVMEDIA_TYPE_AUDIO;
codec_id = AV_CODEC_ID_PCM_DVD;
} else if (startcode >= 0xb0 && startcode <= 0xbf) {
type = AVMEDIA_TYPE_AUDIO;
codec_id = AV_CODEC_ID_TRUEHD;
} else if (startcode >= 0xc0 && startcode <= 0xcf) {
/* Used for both AC-3 and E-AC-3 in EVOB files */
type = AVMEDIA_TYPE_AUDIO;
codec_id = AV_CODEC_ID_AC3;
} else if (startcode >= 0x20 && startcode <= 0x3f) {
type = AVMEDIA_TYPE_SUBTITLE;
codec_id = AV_CODEC_ID_DVD_SUBTITLE;
} else if (startcode >= 0xfd55 && startcode <= 0xfd5f) {
type = AVMEDIA_TYPE_VIDEO;
codec_id = AV_CODEC_ID_VC1;
} else if (startcode == 0x1bd) {
// check dvd audio substream type
type = AVMEDIA_TYPE_AUDIO;
switch (dvdaudio_substream_type & 0xe0) {
case 0xa0:
codec_id = AV_CODEC_ID_PCM_DVD;
break;
case 0x80:
if ((dvdaudio_substream_type & 0xf8) == 0x88)
codec_id = AV_CODEC_ID_DTS;
else
codec_id = AV_CODEC_ID_AC3;
break;
default:
av_log(s, AV_LOG_ERROR, "Unknown 0x1bd sub-stream\n");
goto skip;
}
} else {
skip:
/* skip packet */
avio_skip(s->pb, len);
goto redo;
}
/* no stream found: add a new stream */
st = avformat_new_stream(s, NULL);
if (!st)
goto skip;
st->id = startcode;
st->codec->codec_type = type;
st->codec->codec_id = codec_id;
st->need_parsing = AVSTREAM_PARSE_FULL;
found:
if (st->discard >= AVDISCARD_ALL)
goto skip;
ret = av_get_packet(s->pb, pkt, len);
pkt->pts = pts;
pkt->dts = dts;
pkt->pos = dummy_pos;
pkt->stream_index = st->index;
av_log(s, AV_LOG_TRACE, "%d: pts=%0.3f dts=%0.3f size=%d\n",
pkt->stream_index, pkt->pts / 90000.0, pkt->dts / 90000.0,
pkt->size);
return (ret < 0) ? ret : 0;
}
static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,
int64_t *ppos, int64_t pos_limit)
{
int len, startcode;
int64_t pos, pts, dts;
pos = *ppos;
if (avio_seek(s->pb, pos, SEEK_SET) < 0)
return AV_NOPTS_VALUE;
for (;;) {
len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts);
if (len < 0) {
av_log(s, AV_LOG_TRACE, "none (ret=%d)\n", len);
return AV_NOPTS_VALUE;
}
if (startcode == s->streams[stream_index]->id &&
dts != AV_NOPTS_VALUE) {
break;
}
avio_skip(s->pb, len);
}
av_log(s, AV_LOG_TRACE, "pos=0x%"PRIx64" dts=0x%"PRIx64" %0.3f\n",
pos, dts, dts / 90000.0);
*ppos = pos;
return dts;
}
AVInputFormat ff_mpegps_demuxer = {
.name = "mpeg",
.long_name = NULL_IF_CONFIG_SMALL("MPEG-PS (MPEG-2 Program Stream)"),
.priv_data_size = sizeof(MpegDemuxContext),
.read_probe = mpegps_probe,
.read_header = mpegps_read_header,
.read_packet = mpegps_read_packet,
.read_timestamp = mpegps_read_dts,
.flags = AVFMT_SHOW_IDS | AVFMT_TS_DISCONT,
};