[SCM] libav/experimental: seek support
siretart at users.alioth.debian.org
siretart at users.alioth.debian.org
Sun Jun 30 15:38:20 UTC 2013
The following commit has been merged in the experimental branch:
commit 27f388aa2488aeceb736fa45ea3733e1b5cd1967
Author: Fabrice Bellard <fabrice at bellard.org>
Date: Mon Nov 10 18:47:52 2003 +0000
seek support
Originally committed as revision 2501 to svn://svn.ffmpeg.org/ffmpeg/trunk
diff --git a/libavformat/mpeg.c b/libavformat/mpeg.c
index 9c13855..de26738 100644
--- a/libavformat/mpeg.c
+++ b/libavformat/mpeg.c
@@ -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)
diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
index 6c4f1a1..e7ec00f 100644
--- a/libavformat/mpegts.c
+++ b/libavformat/mpegts.c
@@ -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(×tamp, &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(×tamp, &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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