FFmpeg/libavformat/seek.c
Michael Niedermayer 976a8b2179 Merge remote-tracking branch 'qatar/master'
* qatar/master: (40 commits)
  H.264: template left MB handling
  H.264: faster fill_decode_caches
  H.264: faster write_back_*
  H.264: faster fill_filter_caches
  H.264: make filter_mb_fast support the case of unavailable top mb
  Do not include log.h in avutil.h
  Do not include pixfmt.h in avutil.h
  Do not include rational.h in avutil.h
  Do not include mathematics.h in avutil.h
  Do not include intfloat_readwrite.h in avutil.h
  Remove return statements following infinite loops without break
  RTSP: Doxygen comment cleanup
  doxygen: Escape '\' in Doxygen documentation.
  md5: cosmetics
  md5: use AV_WL32 to write result
  md5: add fate test
  md5: include correct headers
  md5: fix test program
  doxygen: Drop array size declarations from Doxygen parameter names.
  doxygen: Fix parameter names to match the function prototypes.
  ...

Conflicts:
	libavcodec/x86/dsputil_mmx.c
	libavformat/flvenc.c
	libavformat/oggenc.c
	libavformat/wtv.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
2011-07-04 00:45:21 +02:00

520 lines
18 KiB
C

/*
* seek utility functions for use within format handlers
*
* Copyright (c) 2009 Ivan Schreter
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "seek.h"
#include "libavutil/mathematics.h"
#include "libavutil/mem.h"
#include "internal.h"
// NOTE: implementation should be moved here in another patch, to keep patches
// separated.
/**
* helper structure describing keyframe search state of one stream
*/
typedef struct {
int64_t pos_lo; ///< position of the frame with low timestamp in file or INT64_MAX if not found (yet)
int64_t ts_lo; ///< frame presentation timestamp or same as pos_lo for byte seeking
int64_t pos_hi; ///< position of the frame with high timestamp in file or INT64_MAX if not found (yet)
int64_t ts_hi; ///< frame presentation timestamp or same as pos_hi for byte seeking
int64_t last_pos; ///< last known position of a frame, for multi-frame packets
int64_t term_ts; ///< termination timestamp (which TS we already read)
AVRational term_ts_tb; ///< timebase for term_ts
int64_t first_ts; ///< first packet timestamp in this iteration (to fill term_ts later)
AVRational first_ts_tb; ///< timebase for first_ts
int terminated; ///< termination flag for the current iteration
} AVSyncPoint;
/**
* Compute a distance between timestamps.
*
* Distances are only comparable, if same time bases are used for computing
* distances.
*
* @param ts_hi high timestamp
* @param tb_hi high timestamp time base
* @param ts_lo low timestamp
* @param tb_lo low timestamp time base
* @return representation of distance between high and low timestamps
*/
static int64_t ts_distance(int64_t ts_hi,
AVRational tb_hi,
int64_t ts_lo,
AVRational tb_lo)
{
int64_t hi, lo;
hi = ts_hi * tb_hi.num * tb_lo.den;
lo = ts_lo * tb_lo.num * tb_hi.den;
return hi - lo;
}
/**
* Partial search for keyframes in multiple streams.
*
* This routine searches in each stream for the next lower and the next higher
* timestamp compared to the given target timestamp. The search starts at the current
* file position and ends at the file position, where all streams have already been
* examined (or when all higher key frames are found in the first iteration).
*
* This routine is called iteratively with an exponential backoff to find the lower
* timestamp.
*
* @param s format context
* @param timestamp target timestamp (or position, if AVSEEK_FLAG_BYTE)
* @param timebase time base for timestamps
* @param flags seeking flags
* @param sync array with information per stream
* @param keyframes_to_find count of keyframes to find in total
* @param found_lo ptr to the count of already found low timestamp keyframes
* @param found_hi ptr to the count of already found high timestamp keyframes
* @param first_iter flag for first iteration
*/
static void search_hi_lo_keyframes(AVFormatContext *s,
int64_t timestamp,
AVRational timebase,
int flags,
AVSyncPoint *sync,
int keyframes_to_find,
int *found_lo,
int *found_hi,
int first_iter)
{
AVPacket pkt;
AVSyncPoint *sp;
AVStream *st;
int idx;
int flg;
int terminated_count = 0;
int64_t pos;
int64_t pts, dts; // PTS/DTS from stream
int64_t ts; // PTS in stream-local time base or position for byte seeking
AVRational ts_tb; // Time base of the stream or 1:1 for byte seeking
for (;;) {
if (av_read_frame(s, &pkt) < 0) {
// EOF or error, make sure high flags are set
for (idx = 0; idx < s->nb_streams; ++idx) {
if (s->streams[idx]->discard < AVDISCARD_ALL) {
sp = &sync[idx];
if (sp->pos_hi == INT64_MAX) {
// no high frame exists for this stream
(*found_hi)++;
sp->ts_hi = INT64_MAX;
sp->pos_hi = INT64_MAX - 1;
}
}
}
break;
}
idx = pkt.stream_index;
st = s->streams[idx];
if (st->discard >= AVDISCARD_ALL)
// this stream is not active, skip packet
continue;
sp = &sync[idx];
flg = pkt.flags;
pos = pkt.pos;
pts = pkt.pts;
dts = pkt.dts;
if (pts == AV_NOPTS_VALUE)
// some formats don't provide PTS, only DTS
pts = dts;
av_free_packet(&pkt);
// Multi-frame packets only return position for the very first frame.
// Other frames are read with position == -1. Therefore, we note down
// last known position of a frame and use it if a frame without
// position arrives. In this way, it's possible to seek to proper
// position. Additionally, for parsers not providing position at all,
// an approximation will be used (starting position of this iteration).
if (pos < 0)
pos = sp->last_pos;
else
sp->last_pos = pos;
// Evaluate key frames with known TS (or any frames, if AVSEEK_FLAG_ANY set).
if (pts != AV_NOPTS_VALUE &&
((flg & AV_PKT_FLAG_KEY) || (flags & AVSEEK_FLAG_ANY))) {
if (flags & AVSEEK_FLAG_BYTE) {
// for byte seeking, use position as timestamp
ts = pos;
ts_tb.num = 1;
ts_tb.den = 1;
} else {
// otherwise, get stream time_base
ts = pts;
ts_tb = st->time_base;
}
if (sp->first_ts == AV_NOPTS_VALUE) {
// Note down termination timestamp for the next iteration - when
// we encounter a packet with the same timestamp, we will ignore
// any further packets for this stream in next iteration (as they
// are already evaluated).
sp->first_ts = ts;
sp->first_ts_tb = ts_tb;
}
if (sp->term_ts != AV_NOPTS_VALUE &&
av_compare_ts(ts, ts_tb, sp->term_ts, sp->term_ts_tb) > 0) {
// past the end position from last iteration, ignore packet
if (!sp->terminated) {
sp->terminated = 1;
++terminated_count;
if (sp->pos_hi == INT64_MAX) {
// no high frame exists for this stream
(*found_hi)++;
sp->ts_hi = INT64_MAX;
sp->pos_hi = INT64_MAX - 1;
}
if (terminated_count == keyframes_to_find)
break; // all terminated, iteration done
}
continue;
}
if (av_compare_ts(ts, ts_tb, timestamp, timebase) <= 0) {
// keyframe found before target timestamp
if (sp->pos_lo == INT64_MAX) {
// found first keyframe lower than target timestamp
(*found_lo)++;
sp->ts_lo = ts;
sp->pos_lo = pos;
} else if (sp->ts_lo < ts) {
// found a better match (closer to target timestamp)
sp->ts_lo = ts;
sp->pos_lo = pos;
}
}
if (av_compare_ts(ts, ts_tb, timestamp, timebase) >= 0) {
// keyframe found after target timestamp
if (sp->pos_hi == INT64_MAX) {
// found first keyframe higher than target timestamp
(*found_hi)++;
sp->ts_hi = ts;
sp->pos_hi = pos;
if (*found_hi >= keyframes_to_find && first_iter) {
// We found high frame for all. They may get updated
// to TS closer to target TS in later iterations (which
// will stop at start position of previous iteration).
break;
}
} else if (sp->ts_hi > ts) {
// found a better match (actually, shouldn't happen)
sp->ts_hi = ts;
sp->pos_hi = pos;
}
}
}
}
// Clean up the parser.
ff_read_frame_flush(s);
}
int64_t ff_gen_syncpoint_search(AVFormatContext *s,
int stream_index,
int64_t pos,
int64_t ts_min,
int64_t ts,
int64_t ts_max,
int flags)
{
AVSyncPoint *sync, *sp;
AVStream *st;
int i;
int keyframes_to_find = 0;
int64_t curpos;
int64_t step;
int found_lo = 0, found_hi = 0;
int64_t min_distance, distance;
int64_t min_pos = 0;
int first_iter = 1;
AVRational time_base;
if (flags & AVSEEK_FLAG_BYTE) {
// for byte seeking, we have exact 1:1 "timestamps" - positions
time_base.num = 1;
time_base.den = 1;
} else {
if (stream_index >= 0) {
// we have a reference stream, which time base we use
st = s->streams[stream_index];
time_base = st->time_base;
} else {
// no reference stream, use AV_TIME_BASE as reference time base
time_base.num = 1;
time_base.den = AV_TIME_BASE;
}
}
// Initialize syncpoint structures for each stream.
sync = av_malloc(s->nb_streams * sizeof(AVSyncPoint));
if (!sync)
// cannot allocate helper structure
return -1;
for (i = 0; i < s->nb_streams; ++i) {
st = s->streams[i];
sp = &sync[i];
sp->pos_lo = INT64_MAX;
sp->ts_lo = INT64_MAX;
sp->pos_hi = INT64_MAX;
sp->ts_hi = INT64_MAX;
sp->terminated = 0;
sp->first_ts = AV_NOPTS_VALUE;
sp->term_ts = ts_max;
sp->term_ts_tb = time_base;
sp->last_pos = pos;
st->cur_dts = AV_NOPTS_VALUE;
if (st->discard < AVDISCARD_ALL)
++keyframes_to_find;
}
if (!keyframes_to_find) {
// no stream active, error
av_free(sync);
return -1;
}
// Find keyframes in all active streams with timestamp/position just before
// and just after requested timestamp/position.
step = s->pb->buffer_size;
curpos = FFMAX(pos - step / 2, 0);
for (;;) {
avio_seek(s->pb, curpos, SEEK_SET);
search_hi_lo_keyframes(s,
ts, time_base,
flags,
sync,
keyframes_to_find,
&found_lo, &found_hi,
first_iter);
if (found_lo == keyframes_to_find && found_hi == keyframes_to_find)
break; // have all keyframes we wanted
if (!curpos)
break; // cannot go back anymore
curpos = pos - step;
if (curpos < 0)
curpos = 0;
step *= 2;
// switch termination positions
for (i = 0; i < s->nb_streams; ++i) {
st = s->streams[i];
st->cur_dts = AV_NOPTS_VALUE;
sp = &sync[i];
if (sp->first_ts != AV_NOPTS_VALUE) {
sp->term_ts = sp->first_ts;
sp->term_ts_tb = sp->first_ts_tb;
sp->first_ts = AV_NOPTS_VALUE;
}
sp->terminated = 0;
sp->last_pos = curpos;
}
first_iter = 0;
}
// Find actual position to start decoding so that decoder synchronizes
// closest to ts and between ts_min and ts_max.
pos = INT64_MAX;
for (i = 0; i < s->nb_streams; ++i) {
st = s->streams[i];
if (st->discard < AVDISCARD_ALL) {
sp = &sync[i];
min_distance = INT64_MAX;
// Find timestamp closest to requested timestamp within min/max limits.
if (sp->pos_lo != INT64_MAX
&& av_compare_ts(ts_min, time_base, sp->ts_lo, st->time_base) <= 0
&& av_compare_ts(sp->ts_lo, st->time_base, ts_max, time_base) <= 0) {
// low timestamp is in range
min_distance = ts_distance(ts, time_base, sp->ts_lo, st->time_base);
min_pos = sp->pos_lo;
}
if (sp->pos_hi != INT64_MAX
&& av_compare_ts(ts_min, time_base, sp->ts_hi, st->time_base) <= 0
&& av_compare_ts(sp->ts_hi, st->time_base, ts_max, time_base) <= 0) {
// high timestamp is in range, check distance
distance = ts_distance(sp->ts_hi, st->time_base, ts, time_base);
if (distance < min_distance) {
min_distance = distance;
min_pos = sp->pos_hi;
}
}
if (min_distance == INT64_MAX) {
// no timestamp is in range, cannot seek
av_free(sync);
return -1;
}
if (min_pos < pos)
pos = min_pos;
}
}
avio_seek(s->pb, pos, SEEK_SET);
av_free(sync);
return pos;
}
AVParserState *ff_store_parser_state(AVFormatContext *s)
{
int i;
AVStream *st;
AVParserStreamState *ss;
AVParserState *state = av_malloc(sizeof(AVParserState));
if (!state)
return NULL;
state->stream_states = av_malloc(sizeof(AVParserStreamState) * s->nb_streams);
if (!state->stream_states) {
av_free(state);
return NULL;
}
state->fpos = avio_tell(s->pb);
// copy context structures
state->cur_st = s->cur_st;
state->packet_buffer = s->packet_buffer;
state->raw_packet_buffer = s->raw_packet_buffer;
state->raw_packet_buffer_remaining_size = s->raw_packet_buffer_remaining_size;
s->cur_st = NULL;
s->packet_buffer = NULL;
s->raw_packet_buffer = NULL;
s->raw_packet_buffer_remaining_size = RAW_PACKET_BUFFER_SIZE;
// copy stream structures
state->nb_streams = s->nb_streams;
for (i = 0; i < s->nb_streams; i++) {
st = s->streams[i];
ss = &state->stream_states[i];
ss->parser = st->parser;
ss->last_IP_pts = st->last_IP_pts;
ss->cur_dts = st->cur_dts;
ss->reference_dts = st->reference_dts;
ss->cur_ptr = st->cur_ptr;
ss->cur_len = st->cur_len;
ss->probe_packets = st->probe_packets;
ss->cur_pkt = st->cur_pkt;
st->parser = NULL;
st->last_IP_pts = AV_NOPTS_VALUE;
st->cur_dts = AV_NOPTS_VALUE;
st->reference_dts = AV_NOPTS_VALUE;
st->cur_ptr = NULL;
st->cur_len = 0;
st->probe_packets = MAX_PROBE_PACKETS;
av_init_packet(&st->cur_pkt);
}
return state;
}
void ff_restore_parser_state(AVFormatContext *s, AVParserState *state)
{
int i;
AVStream *st;
AVParserStreamState *ss;
ff_read_frame_flush(s);
if (!state)
return;
avio_seek(s->pb, state->fpos, SEEK_SET);
// copy context structures
s->cur_st = state->cur_st;
s->packet_buffer = state->packet_buffer;
s->raw_packet_buffer = state->raw_packet_buffer;
s->raw_packet_buffer_remaining_size = state->raw_packet_buffer_remaining_size;
// copy stream structures
for (i = 0; i < state->nb_streams; i++) {
st = s->streams[i];
ss = &state->stream_states[i];
st->parser = ss->parser;
st->last_IP_pts = ss->last_IP_pts;
st->cur_dts = ss->cur_dts;
st->reference_dts = ss->reference_dts;
st->cur_ptr = ss->cur_ptr;
st->cur_len = ss->cur_len;
st->probe_packets = ss->probe_packets;
st->cur_pkt = ss->cur_pkt;
}
av_free(state->stream_states);
av_free(state);
}
static void free_packet_list(AVPacketList *pktl)
{
AVPacketList *cur;
while (pktl) {
cur = pktl;
pktl = cur->next;
av_free_packet(&cur->pkt);
av_free(cur);
}
}
void ff_free_parser_state(AVFormatContext *s, AVParserState *state)
{
int i;
AVParserStreamState *ss;
if (!state)
return;
for (i = 0; i < state->nb_streams; i++) {
ss = &state->stream_states[i];
if (ss->parser)
av_parser_close(ss->parser);
av_free_packet(&ss->cur_pkt);
}
free_packet_list(state->packet_buffer);
free_packet_list(state->raw_packet_buffer);
av_free(state->stream_states);
av_free(state);
}