diff options
Diffstat (limited to 'libavformat/seek.c')
-rw-r--r-- | libavformat/seek.c | 507 |
1 files changed, 0 insertions, 507 deletions
diff --git a/libavformat/seek.c b/libavformat/seek.c deleted file mode 100644 index 967f282d51..0000000000 --- a/libavformat/seek.c +++ /dev/null @@ -1,507 +0,0 @@ -/* - * 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 <stdint.h> - -#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_array(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_array(s->nb_streams, sizeof(AVParserStreamState)); - if (!state->stream_states) { - av_free(state); - return NULL; - } - - state->fpos = avio_tell(s->pb); - - // copy context structures - state->packet_buffer = s->packet_buffer; - state->parse_queue = s->parse_queue; - state->raw_packet_buffer = s->raw_packet_buffer; - state->raw_packet_buffer_remaining_size = s->raw_packet_buffer_remaining_size; - - s->packet_buffer = NULL; - s->parse_queue = 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->probe_packets = st->probe_packets; - - st->parser = NULL; - st->last_IP_pts = AV_NOPTS_VALUE; - st->cur_dts = AV_NOPTS_VALUE; - st->probe_packets = MAX_PROBE_PACKETS; - } - - 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->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); -} - -static void free_packet_list(AVPacketList *pktl) -{ - while (pktl) { - AVPacketList *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); - } - - free_packet_list(state->packet_buffer); - free_packet_list(state->parse_queue); - free_packet_list(state->raw_packet_buffer); - - av_freep(&state->stream_states); - av_freep(&state); -} |