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seek support

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Originally committed as revision 2501 to svn://svn.ffmpeg.org/ffmpeg/trunk
pull/126/head
Fabrice Bellard 22 years ago
parent f9b5459e79
commit 27f388aa24
2 changed files with 424 additions and 37 deletions
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  1. 303
      libavformat/mpeg.c
  2. 158
      libavformat/mpegts.c

303
libavformat/mpeg.c
Unescape View File

@ -20,6 +20,7 @@
#define MAX_PAYLOAD_SIZE 4096
#define NB_STREAMS 2
//#define DEBUG_SEEK
typedef struct {
uint8_t buffer[MAX_PAYLOAD_SIZE];
@ -447,8 +448,34 @@ typedef struct MpegDemuxContext {
int header_state;
} MpegDemuxContext;
static int find_start_code(ByteIOContext *pb, int *size_ptr,
uint32_t *header_state)
static int mpegps_read_header(AVFormatContext *s,
AVFormatParameters *ap)
{
MpegDemuxContext *m = s->priv_data;
m->header_state = 0xff;
s->ctx_flags |= AVFMTCTX_NOHEADER;
/* no need to do more */
return 0;
}
static int64_t get_pts(ByteIOContext *pb, int c)
{
int64_t pts;
int val;
if (c < 0)
c = get_byte(pb);
pts = (int64_t)((c >> 1) & 0x07) << 30;
val = get_be16(pb);
pts |= (int64_t)(val >> 1) << 15;
val = get_be16(pb);
pts |= (int64_t)(val >> 1);
return pts;
}
static int find_next_start_code(ByteIOContext *pb, int *size_ptr,
uint32_t *header_state)
{
unsigned int state, v;
int val, n;
@ -474,45 +501,64 @@ static int find_start_code(ByteIOContext *pb, int *size_ptr,
return val;
}
static int mpegps_read_header(AVFormatContext *s,
AVFormatParameters *ap)
/* XXX: optimize */
static int find_prev_start_code(ByteIOContext *pb, int *size_ptr)
{
MpegDemuxContext *m = s->priv_data;
m->header_state = 0xff;
s->ctx_flags |= AVFMTCTX_NOHEADER;
int64_t pos, pos_start;
int max_size, start_code;
/* no need to do more */
return 0;
}
max_size = *size_ptr;
pos_start = url_ftell(pb);
static int64_t get_pts(ByteIOContext *pb, int c)
{
int64_t pts;
int val;
/* in order to go faster, we fill the buffer */
pos = pos_start - 16386;
if (pos < 0)
pos = 0;
url_fseek(pb, pos, SEEK_SET);
get_byte(pb);
if (c < 0)
c = get_byte(pb);
pts = (int64_t)((c >> 1) & 0x07) << 30;
val = get_be16(pb);
pts |= (int64_t)(val >> 1) << 15;
val = get_be16(pb);
pts |= (int64_t)(val >> 1);
return pts;
pos = pos_start;
for(;;) {
pos--;
if (pos < 0 || (pos_start - pos) >= max_size) {
start_code = -1;
goto the_end;
}
url_fseek(pb, pos, SEEK_SET);
start_code = get_be32(pb);
if ((start_code & 0xffffff00) == 0x100)
break;
}
the_end:
*size_ptr = pos_start - pos;
return start_code;
}
static int mpegps_read_packet(AVFormatContext *s,
AVPacket *pkt)
/* read the next (or previous) 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, int find_next)
{
MpegDemuxContext *m = s->priv_data;
AVStream *st;
int len, size, startcode, i, c, flags, header_len, type, codec_id;
int64_t pts, dts;
int len, size, startcode, c, flags, header_len;
int64_t pts, dts, last_pos;
/* next start code (should be immediately after) */
last_pos = -1;
redo:
m->header_state = 0xff;
size = MAX_SYNC_SIZE;
startcode = find_start_code(&s->pb, &size, &m->header_state);
if (find_next) {
/* 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);
} else {
if (last_pos >= 0)
url_fseek(&s->pb, last_pos, SEEK_SET);
size = MAX_SYNC_SIZE;
startcode = find_prev_start_code(&s->pb, &size);
last_pos = url_ftell(&s->pb) - 4;
}
//printf("startcode=%x pos=0x%Lx\n", startcode, url_ftell(&s->pb));
if (startcode < 0)
return -EIO;
@ -532,12 +578,16 @@ static int mpegps_read_packet(AVFormatContext *s,
(startcode >= 0x1e0 && startcode <= 0x1ef) ||
(startcode == 0x1bd)))
goto redo;
if (ppos) {
*ppos = url_ftell(&s->pb) - 4;
}
len = get_be16(&s->pb);
pts = AV_NOPTS_VALUE;
dts = AV_NOPTS_VALUE;
/* stuffing */
for(;;) {
if (len < 1)
goto redo;
c = get_byte(&s->pb);
len--;
/* XXX: for mpeg1, should test only bit 7 */
@ -546,22 +596,28 @@ static int mpegps_read_packet(AVFormatContext *s,
}
if ((c & 0xc0) == 0x40) {
/* buffer scale & size */
if (len < 2)
goto redo;
get_byte(&s->pb);
c = get_byte(&s->pb);
len -= 2;
}
if ((c & 0xf0) == 0x20) {
pts = get_pts(&s->pb, c);
if (len < 4)
goto redo;
dts = pts = get_pts(&s->pb, c);
len -= 4;
} else if ((c & 0xf0) == 0x30) {
if (len < 9)
goto redo;
pts = get_pts(&s->pb, c);
dts = get_pts(&s->pb, -1);
len -= 9;
} else if ((c & 0xc0) == 0x80) {
/* mpeg 2 PES */
if ((c & 0x30) != 0) {
fprintf(stderr, "Encrypted multiplex not handled\n");
return -EIO;
/* Encrypted multiplex not handled */
goto redo;
}
flags = get_byte(&s->pb);
header_len = get_byte(&s->pb);
@ -569,12 +625,16 @@ static int mpegps_read_packet(AVFormatContext *s,
if (header_len > len)
goto redo;
if ((flags & 0xc0) == 0x80) {
pts = get_pts(&s->pb, -1);
dts = pts = get_pts(&s->pb, -1);
if (header_len < 5)
goto redo;
header_len -= 5;
len -= 5;
} if ((flags & 0xc0) == 0xc0) {
pts = get_pts(&s->pb, -1);
dts = get_pts(&s->pb, -1);
if (header_len < 10)
goto redo;
header_len -= 10;
len -= 10;
}
@ -585,16 +645,37 @@ static int mpegps_read_packet(AVFormatContext *s,
}
}
if (startcode == 0x1bd) {
if (len < 1)
goto redo;
startcode = get_byte(&s->pb);
len--;
if (startcode >= 0x80 && startcode <= 0xbf) {
/* audio: skip header */
if (len < 3)
goto redo;
get_byte(&s->pb);
get_byte(&s->pb);
get_byte(&s->pb);
len -= 3;
}
}
*pstart_code = startcode;
*ppts = pts;
*pdts = dts;
return len;
}
static int mpegps_read_packet(AVFormatContext *s,
AVPacket *pkt)
{
AVStream *st;
int len, startcode, i, type, codec_id;
int64_t pts, dts;
redo:
len = mpegps_read_pes_header(s, NULL, &startcode, &pts, &dts, 1);
if (len < 0)
return len;
/* now find stream */
for(i=0;i<s->nb_streams;i++) {
@ -626,6 +707,8 @@ static int mpegps_read_packet(AVFormatContext *s,
goto skip;
st->codec.codec_type = type;
st->codec.codec_id = codec_id;
if (codec_id != CODEC_ID_PCM_S16BE)
st->need_parsing = 1;
found:
if (startcode >= 0xa0 && startcode <= 0xbf) {
int b1, freq;
@ -649,6 +732,7 @@ static int mpegps_read_packet(AVFormatContext *s,
// (float)pts/90000, len);
get_buffer(&s->pb, pkt->data, pkt->size);
pkt->pts = pts;
pkt->dts = dts;
pkt->stream_index = st->index;
return 0;
}
@ -658,6 +742,152 @@ static int mpegps_read_close(AVFormatContext *s)
return 0;
}
static int64_t mpegps_read_dts(AVFormatContext *s, int stream_index,
int64_t *ppos, int find_next)
{
int len, startcode;
int64_t pos, pts, dts;
pos = *ppos;
#ifdef DEBUG_SEEK
printf("read_dts: pos=0x%llx next=%d -> ", pos, find_next);
#endif
url_fseek(&s->pb, pos, SEEK_SET);
for(;;) {
len = mpegps_read_pes_header(s, &pos, &startcode, &pts, &dts, find_next);
if (len < 0) {
#ifdef DEBUG_SEEK
printf("none (ret=%d)\n", len);
#endif
return AV_NOPTS_VALUE;
}
if (startcode == s->streams[stream_index]->id &&
dts != AV_NOPTS_VALUE) {
break;
}
if (find_next) {
url_fskip(&s->pb, len);
} else {
url_fseek(&s->pb, pos, SEEK_SET);
}
}
#ifdef DEBUG_SEEK
printf("pos=0x%llx dts=0x%llx %0.3f\n", pos, dts, dts / 90000.0);
#endif
*ppos = pos;
return dts;
}
static int find_stream_index(AVFormatContext *s)
{
int i;
AVStream *st;
if (s->nb_streams <= 0)
return -1;
for(i = 0; i < s->nb_streams; i++) {
st = s->streams[i];
if (st->codec.codec_type == CODEC_TYPE_VIDEO) {
return i;
}
}
return 0;
}
static int mpegps_read_seek(AVFormatContext *s,
int stream_index, int64_t timestamp)
{
int64_t pos_min, pos_max, pos;
int64_t dts_min, dts_max, dts;
timestamp = (timestamp * 90000) / AV_TIME_BASE;
#ifdef DEBUG_SEEK
printf("read_seek: %d %0.3f\n", stream_index, timestamp / 90000.0);
#endif
/* XXX: find stream_index by looking at the first PES packet found */
if (stream_index < 0) {
stream_index = find_stream_index(s);
if (stream_index < 0)
return -1;
}
pos_min = 0;
dts_min = mpegps_read_dts(s, stream_index, &pos_min, 1);
if (dts_min == AV_NOPTS_VALUE) {
/* we can reach this case only if no PTS are present in
the whole stream */
return -1;
}
pos_max = url_filesize(url_fileno(&s->pb)) - 1;
dts_max = mpegps_read_dts(s, stream_index, &pos_max, 0);
while (pos_min <= pos_max) {
#ifdef DEBUG_SEEK
printf("pos_min=0x%llx pos_max=0x%llx dts_min=%0.3f dts_max=%0.3f\n",
pos_min, pos_max,
dts_min / 90000.0, dts_max / 90000.0);
#endif
if (timestamp <= dts_min) {
pos = pos_min;
goto found;
} else if (timestamp >= dts_max) {
pos = pos_max;
goto found;
} else {
/* interpolate position (better than dichotomy) */
pos = (int64_t)((double)(pos_max - pos_min) *
(double)(timestamp - dts_min) /
(double)(dts_max - dts_min)) + pos_min;
}
#ifdef DEBUG_SEEK
printf("pos=0x%llx\n", pos);
#endif
/* read the next timestamp */
dts = mpegps_read_dts(s, stream_index, &pos, 1);
/* check if we are lucky */
if (dts == AV_NOPTS_VALUE) {
/* should never happen */
pos = pos_min;
goto found;
} else if (timestamp == dts) {
goto found;
} else if (timestamp < dts) {
pos_max = pos;
dts_max = mpegps_read_dts(s, stream_index, &pos_max, 0);
if (dts_max == AV_NOPTS_VALUE) {
/* should never happen */
break;
} else if (timestamp >= dts_max) {
pos = pos_max;
goto found;
}
} else {
pos_min = pos + 1;
dts_min = mpegps_read_dts(s, stream_index, &pos_min, 1);
if (dts_min == AV_NOPTS_VALUE) {
/* should never happen */
goto found;
} else if (timestamp <= dts_min) {
goto found;
}
}
}
pos = pos_min;
found:
#ifdef DEBUG_SEEK
pos_min = pos;
dts_min = mpegps_read_dts(s, stream_index, &pos_min, 1);
pos_min++;
dts_max = mpegps_read_dts(s, stream_index, &pos_min, 1);
printf("pos=0x%llx %0.3f<=%0.3f<=%0.3f\n",
pos, dts_min / 90000.0, timestamp / 90000.0, dts_max / 90000.0);
#endif
/* do the seek */
url_fseek(&s->pb, pos, SEEK_SET);
return 0;
}
#ifdef CONFIG_ENCODERS
static AVOutputFormat mpeg1system_mux = {
"mpeg",
@ -707,6 +937,7 @@ AVInputFormat mpegps_demux = {
mpegps_read_header,
mpegps_read_packet,
mpegps_read_close,
mpegps_read_seek,
};
int mpegps_init(void)

158
libavformat/mpegts.c
Unescape View File

@ -21,6 +21,7 @@
#include "mpegts.h"
//#define DEBUG_SI
//#define DEBUG_SEEK
/* 1.0 second at 24Mbit/s */
#define MAX_SCAN_PACKETS 32000
@ -87,7 +88,8 @@ struct MpegTSContext {
/* used to estimate the exact PCR */
int64_t cur_pcr;
int pcr_incr;
int pcr_pid;
/* data needed to handle file based ts */
int stop_parse; /* stop parsing loop */
AVPacket *pkt; /* packet containing av data */
@ -367,6 +369,7 @@ static void pmt_cb(void *opaque, const uint8_t *section, int section_len)
pcr_pid = get16(&p, p_end) & 0x1fff;
if (pcr_pid < 0)
return;
ts->pcr_pid = pcr_pid;
#ifdef DEBUG_SI
printf("pcr_pid=0x%x\n", pcr_pid);
#endif
@ -710,6 +713,7 @@ static void mpegts_push_data(void *opaque,
st->priv_data = pes;
st->codec.codec_type = codec_type;
st->codec.codec_id = codec_id;
st->need_parsing = 1;
pes->st = st;
}
}
@ -1117,6 +1121,7 @@ static int mpegts_read_header(AVFormatContext *s,
}
nb_packets++;
}
ts->pcr_pid = pcr_pid;
/* NOTE1: the bitrate is computed without the FEC */
/* NOTE2: it is only the bitrate of the start of the stream */
@ -1204,6 +1209,156 @@ static int mpegts_read_close(AVFormatContext *s)
return 0;
}
static int64_t mpegts_get_pcr(AVFormatContext *s, int stream_index,
int64_t *ppos, int find_next)
{
MpegTSContext *ts = s->priv_data;
int64_t pos, timestamp;
uint8_t buf[TS_PACKET_SIZE];
int pcr_l, pid;
pos = *ppos;
if (find_next) {
for(;;) {
url_fseek(&s->pb, pos, SEEK_SET);
if (get_buffer(&s->pb, buf, TS_PACKET_SIZE) != TS_PACKET_SIZE)
return AV_NOPTS_VALUE;
pid = ((buf[1] & 0x1f) << 8) | buf[2];
if (pid == ts->pcr_pid &&
parse_pcr(&timestamp, &pcr_l, buf) == 0) {
break;
}
pos += ts->raw_packet_size;
}
} else {
for(;;) {
pos -= ts->raw_packet_size;
if (pos < 0)
return AV_NOPTS_VALUE;
url_fseek(&s->pb, pos, SEEK_SET);
if (get_buffer(&s->pb, buf, TS_PACKET_SIZE) != TS_PACKET_SIZE)
return AV_NOPTS_VALUE;
pid = ((buf[1] & 0x1f) << 8) | buf[2];
if (pid == ts->pcr_pid &&
parse_pcr(&timestamp, &pcr_l, buf) == 0) {
break;
}
}
}
*ppos = pos;
return timestamp;
}
typedef int64_t ReadTimestampFunc(AVFormatContext *s, int stream_index,
int64_t *ppos, int find_next);
static int64_t do_block_align(int64_t val, int block_align)
{
return (val / block_align) * block_align;
}
/* XXX: use it in other formats */
static int timestamp_read_seek(AVFormatContext *s,
int stream_index, int64_t timestamp,
ReadTimestampFunc *read_timestamp,
int block_align)
{
int64_t pos_min, pos_max, pos;
int64_t dts_min, dts_max, dts;
#ifdef DEBUG_SEEK
printf("read_seek: %d %0.3f\n", stream_index, timestamp / 90000.0);
#endif
pos_min = 0;
dts_min = read_timestamp(s, stream_index, &pos_min, 1);
if (dts_min == AV_NOPTS_VALUE) {
/* we can reach this case only if no PTS are present in
the whole stream */
return -1;
}
pos_max = do_block_align(url_filesize(url_fileno(&s->pb)), block_align) -
block_align;
dts_max = read_timestamp(s, stream_index, &pos_max, 0);
while (pos_min <= pos_max) {
#ifdef DEBUG_SEEK
printf("pos_min=0x%llx pos_max=0x%llx dts_min=%0.3f dts_max=%0.3f\n",
pos_min, pos_max,
dts_min / 90000.0, dts_max / 90000.0);
#endif
if (timestamp <= dts_min) {
pos = pos_min;
goto found;
} else if (timestamp >= dts_max) {
pos = pos_max;
goto found;
} else {
/* interpolate position (better than dichotomy) */
pos = (int64_t)((double)(pos_max - pos_min) *
(double)(timestamp - dts_min) /
(double)(dts_max - dts_min)) + pos_min;
pos = do_block_align(pos, block_align);
}
#ifdef DEBUG_SEEK
printf("pos=0x%llx\n", pos);
#endif
/* read the next timestamp */
dts = read_timestamp(s, stream_index, &pos, 1);
/* check if we are lucky */
if (dts == AV_NOPTS_VALUE) {
/* should never happen */
pos = pos_min;
goto found;
} else if (timestamp == dts) {
goto found;
} else if (timestamp < dts) {
pos_max = pos;
dts_max = read_timestamp(s, stream_index, &pos_max, 0);
if (dts_max == AV_NOPTS_VALUE) {
/* should never happen */
break;
} else if (timestamp >= dts_max) {
pos = pos_max;
goto found;
}
} else {
pos_min = pos + block_align;
dts_min = read_timestamp(s, stream_index, &pos_min, 1);
if (dts_min == AV_NOPTS_VALUE) {
/* should never happen */
goto found;
} else if (timestamp <= dts_min) {
goto found;
}
}
}
pos = pos_min;
found:
#ifdef DEBUG_SEEK
pos_min = pos;
dts_min = read_timestamp(s, stream_index, &pos_min, 1);
pos_min += block_align;
dts_max = read_timestamp(s, stream_index, &pos_min, 1);
printf("pos=0x%llx %0.3f<=%0.3f<=%0.3f\n",
pos, dts_min / 90000.0, timestamp / 90000.0, dts_max / 90000.0);
#endif
/* do the seek */
url_fseek(&s->pb, pos, SEEK_SET);
return 0;
}
static int mpegts_read_seek(AVFormatContext *s,
int stream_index, int64_t timestamp)
{
MpegTSContext *ts = s->priv_data;
timestamp = (timestamp * 90000) / AV_TIME_BASE;
return timestamp_read_seek(s, stream_index, timestamp,
mpegts_get_pcr, ts->raw_packet_size);
}
/**************************************************************/
/* parsing functions - called from other demuxers such as RTP */
@ -1265,6 +1420,7 @@ AVInputFormat mpegts_demux = {
mpegts_read_header,
mpegts_read_packet,
mpegts_read_close,
mpegts_read_seek,
.flags = AVFMT_SHOW_IDS,
};

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