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seek support

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Originally committed as revision 2501 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Fabrice Bellard
2003-11-10 18:47:52 +00:00
parent f9b5459e79
commit 27f388aa24
2 changed files with 426 additions and 39 deletions
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158
libavformat/mpegts.c
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@@ -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,
};