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FFmpeg/libavformat/mpeg.c
Anton Khirnov 9200514ad8 lavf: replace AVStream.codec with AVStream.codecpar 
Currently, AVStream contains an embedded AVCodecContext instance, which
is used by demuxers to export stream parameters to the caller and by
muxers to receive stream parameters from the caller. It is also used
internally as the codec context that is passed to parsers.

In addition, it is also widely used by the callers as the decoding (when
demuxer) or encoding (when muxing) context, though this has been
officially discouraged since Libav 11.

There are multiple important problems with this approach:
    - the fields in AVCodecContext are in general one of
        * stream parameters
        * codec options
        * codec state
      However, it's not clear which ones are which. It is consequently
      unclear which fields are a demuxer allowed to set or a muxer allowed to
      read. This leads to erratic behaviour depending on whether decoding or
      encoding is being performed or not (and whether it uses the AVStream
      embedded codec context).
    - various synchronization issues arising from the fact that the same
      context is used by several different APIs (muxers/demuxers,
      parsers, bitstream filters and encoders/decoders) simultaneously, with
      there being no clear rules for who can modify what and the different
      processes being typically delayed with respect to each other.
    - avformat_find_stream_info() making it necessary to support opening
      and closing a single codec context multiple times, thus
      complicating the semantics of freeing various allocated objects in the
      codec context.

Those problems are resolved by replacing the AVStream embedded codec
context with a newly added AVCodecParameters instance, which stores only
the stream parameters exported by the demuxers or read by the muxers.
2016-02-23 17:01:58 +01:00

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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->codecpar->codec_type = type;
st->codecpar->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,
};
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