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->packet_buffer = state->packet_buffer;
s->parse_queue = state->parse_queue;
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->probe_packets = ss->probe_packets;
}
av_freep(&state->stream_states);
av_freep(&state);
}
/**
* 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);
}
