yading@11: /*
yading@11:  * seek utility functions for use within format handlers
yading@11:  *
yading@11:  * Copyright (c) 2009 Ivan Schreter
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #include "seek.h"
yading@11: #include "libavutil/mathematics.h"
yading@11: #include "libavutil/mem.h"
yading@11: #include "internal.h"
yading@11: 
yading@11: // NOTE: implementation should be moved here in another patch, to keep patches
yading@11: // separated.
yading@11: 
yading@11: /**
yading@11:  * helper structure describing keyframe search state of one stream
yading@11:  */
yading@11: typedef struct {
yading@11:     int64_t     pos_lo;      ///< position of the frame with low timestamp in file or INT64_MAX if not found (yet)
yading@11:     int64_t     ts_lo;       ///< frame presentation timestamp or same as pos_lo for byte seeking
yading@11: 
yading@11:     int64_t     pos_hi;      ///< position of the frame with high timestamp in file or INT64_MAX if not found (yet)
yading@11:     int64_t     ts_hi;       ///< frame presentation timestamp or same as pos_hi for byte seeking
yading@11: 
yading@11:     int64_t     last_pos;    ///< last known position of a frame, for multi-frame packets
yading@11: 
yading@11:     int64_t     term_ts;     ///< termination timestamp (which TS we already read)
yading@11:     AVRational  term_ts_tb;  ///< timebase for term_ts
yading@11:     int64_t     first_ts;    ///< first packet timestamp in this iteration (to fill term_ts later)
yading@11:     AVRational  first_ts_tb; ///< timebase for first_ts
yading@11: 
yading@11:     int         terminated;  ///< termination flag for the current iteration
yading@11: } AVSyncPoint;
yading@11: 
yading@11: /**
yading@11:  * Compute a distance between timestamps.
yading@11:  *
yading@11:  * Distances are only comparable, if same time bases are used for computing
yading@11:  * distances.
yading@11:  *
yading@11:  * @param ts_hi high timestamp
yading@11:  * @param tb_hi high timestamp time base
yading@11:  * @param ts_lo low timestamp
yading@11:  * @param tb_lo low timestamp time base
yading@11:  * @return representation of distance between high and low timestamps
yading@11:  */
yading@11: static int64_t ts_distance(int64_t ts_hi,
yading@11:                            AVRational tb_hi,
yading@11:                            int64_t ts_lo,
yading@11:                            AVRational tb_lo)
yading@11: {
yading@11:     int64_t hi, lo;
yading@11: 
yading@11:     hi = ts_hi * tb_hi.num * tb_lo.den;
yading@11:     lo = ts_lo * tb_lo.num * tb_hi.den;
yading@11: 
yading@11:     return hi - lo;
yading@11: }
yading@11: 
yading@11: /**
yading@11:  * Partial search for keyframes in multiple streams.
yading@11:  *
yading@11:  * This routine searches in each stream for the next lower and the next higher
yading@11:  * timestamp compared to the given target timestamp. The search starts at the current
yading@11:  * file position and ends at the file position, where all streams have already been
yading@11:  * examined (or when all higher key frames are found in the first iteration).
yading@11:  *
yading@11:  * This routine is called iteratively with an exponential backoff to find the lower
yading@11:  * timestamp.
yading@11:  *
yading@11:  * @param s                 format context
yading@11:  * @param timestamp         target timestamp (or position, if AVSEEK_FLAG_BYTE)
yading@11:  * @param timebase          time base for timestamps
yading@11:  * @param flags             seeking flags
yading@11:  * @param sync              array with information per stream
yading@11:  * @param keyframes_to_find count of keyframes to find in total
yading@11:  * @param found_lo          ptr to the count of already found low timestamp keyframes
yading@11:  * @param found_hi          ptr to the count of already found high timestamp keyframes
yading@11:  * @param first_iter        flag for first iteration
yading@11:  */
yading@11: static void search_hi_lo_keyframes(AVFormatContext *s,
yading@11:                                    int64_t timestamp,
yading@11:                                    AVRational timebase,
yading@11:                                    int flags,
yading@11:                                    AVSyncPoint *sync,
yading@11:                                    int keyframes_to_find,
yading@11:                                    int *found_lo,
yading@11:                                    int *found_hi,
yading@11:                                    int first_iter)
yading@11: {
yading@11:     AVPacket pkt;
yading@11:     AVSyncPoint *sp;
yading@11:     AVStream *st;
yading@11:     int idx;
yading@11:     int flg;
yading@11:     int terminated_count = 0;
yading@11:     int64_t pos;
yading@11:     int64_t pts, dts;   // PTS/DTS from stream
yading@11:     int64_t ts;         // PTS in stream-local time base or position for byte seeking
yading@11:     AVRational ts_tb;   // Time base of the stream or 1:1 for byte seeking
yading@11: 
yading@11:     for (;;) {
yading@11:         if (av_read_frame(s, &pkt) < 0) {
yading@11:             // EOF or error, make sure high flags are set
yading@11:             for (idx = 0; idx < s->nb_streams; ++idx) {
yading@11:                 if (s->streams[idx]->discard < AVDISCARD_ALL) {
yading@11:                     sp = &sync[idx];
yading@11:                     if (sp->pos_hi == INT64_MAX) {
yading@11:                         // no high frame exists for this stream
yading@11:                         (*found_hi)++;
yading@11:                         sp->ts_hi  = INT64_MAX;
yading@11:                         sp->pos_hi = INT64_MAX - 1;
yading@11:                     }
yading@11:                 }
yading@11:             }
yading@11:             break;
yading@11:         }
yading@11: 
yading@11:         idx = pkt.stream_index;
yading@11:         st = s->streams[idx];
yading@11:         if (st->discard >= AVDISCARD_ALL)
yading@11:             // this stream is not active, skip packet
yading@11:             continue;
yading@11: 
yading@11:         sp = &sync[idx];
yading@11: 
yading@11:         flg = pkt.flags;
yading@11:         pos = pkt.pos;
yading@11:         pts = pkt.pts;
yading@11:         dts = pkt.dts;
yading@11:         if (pts == AV_NOPTS_VALUE)
yading@11:             // some formats don't provide PTS, only DTS
yading@11:             pts = dts;
yading@11: 
yading@11:         av_free_packet(&pkt);
yading@11: 
yading@11:         // Multi-frame packets only return position for the very first frame.
yading@11:         // Other frames are read with position == -1. Therefore, we note down
yading@11:         // last known position of a frame and use it if a frame without
yading@11:         // position arrives. In this way, it's possible to seek to proper
yading@11:         // position. Additionally, for parsers not providing position at all,
yading@11:         // an approximation will be used (starting position of this iteration).
yading@11:         if (pos < 0)
yading@11:             pos = sp->last_pos;
yading@11:         else
yading@11:             sp->last_pos = pos;
yading@11: 
yading@11:         // Evaluate key frames with known TS (or any frames, if AVSEEK_FLAG_ANY set).
yading@11:         if (pts != AV_NOPTS_VALUE &&
yading@11:             ((flg & AV_PKT_FLAG_KEY) || (flags & AVSEEK_FLAG_ANY))) {
yading@11:             if (flags & AVSEEK_FLAG_BYTE) {
yading@11:                 // for byte seeking, use position as timestamp
yading@11:                 ts        = pos;
yading@11:                 ts_tb.num = 1;
yading@11:                 ts_tb.den = 1;
yading@11:             } else {
yading@11:                 // otherwise, get stream time_base
yading@11:                 ts    = pts;
yading@11:                 ts_tb = st->time_base;
yading@11:             }
yading@11: 
yading@11:             if (sp->first_ts == AV_NOPTS_VALUE) {
yading@11:                 // Note down termination timestamp for the next iteration - when
yading@11:                 // we encounter a packet with the same timestamp, we will ignore
yading@11:                 // any further packets for this stream in next iteration (as they
yading@11:                 // are already evaluated).
yading@11:                 sp->first_ts    = ts;
yading@11:                 sp->first_ts_tb = ts_tb;
yading@11:             }
yading@11: 
yading@11:             if (sp->term_ts != AV_NOPTS_VALUE &&
yading@11:                 av_compare_ts(ts, ts_tb, sp->term_ts, sp->term_ts_tb) > 0) {
yading@11:                 // past the end position from last iteration, ignore packet
yading@11:                 if (!sp->terminated) {
yading@11:                     sp->terminated = 1;
yading@11:                     ++terminated_count;
yading@11:                     if (sp->pos_hi == INT64_MAX) {
yading@11:                         // no high frame exists for this stream
yading@11:                         (*found_hi)++;
yading@11:                         sp->ts_hi  = INT64_MAX;
yading@11:                         sp->pos_hi = INT64_MAX - 1;
yading@11:                     }
yading@11:                     if (terminated_count == keyframes_to_find)
yading@11:                         break;  // all terminated, iteration done
yading@11:                 }
yading@11:                 continue;
yading@11:             }
yading@11: 
yading@11:             if (av_compare_ts(ts, ts_tb, timestamp, timebase) <= 0) {
yading@11:                 // keyframe found before target timestamp
yading@11:                 if (sp->pos_lo == INT64_MAX) {
yading@11:                     // found first keyframe lower than target timestamp
yading@11:                     (*found_lo)++;
yading@11:                     sp->ts_lo  = ts;
yading@11:                     sp->pos_lo = pos;
yading@11:                 } else if (sp->ts_lo < ts) {
yading@11:                     // found a better match (closer to target timestamp)
yading@11:                     sp->ts_lo  = ts;
yading@11:                     sp->pos_lo = pos;
yading@11:                 }
yading@11:             }
yading@11:             if (av_compare_ts(ts, ts_tb, timestamp, timebase) >= 0) {
yading@11:                 // keyframe found after target timestamp
yading@11:                 if (sp->pos_hi == INT64_MAX) {
yading@11:                     // found first keyframe higher than target timestamp
yading@11:                     (*found_hi)++;
yading@11:                     sp->ts_hi  = ts;
yading@11:                     sp->pos_hi = pos;
yading@11:                     if (*found_hi >= keyframes_to_find && first_iter) {
yading@11:                         // We found high frame for all. They may get updated
yading@11:                         // to TS closer to target TS in later iterations (which
yading@11:                         // will stop at start position of previous iteration).
yading@11:                         break;
yading@11:                     }
yading@11:                 } else if (sp->ts_hi > ts) {
yading@11:                     // found a better match (actually, shouldn't happen)
yading@11:                     sp->ts_hi  = ts;
yading@11:                     sp->pos_hi = pos;
yading@11:                 }
yading@11:             }
yading@11:         }
yading@11:     }
yading@11: 
yading@11:     // Clean up the parser.
yading@11:     ff_read_frame_flush(s);
yading@11: }
yading@11: 
yading@11: int64_t ff_gen_syncpoint_search(AVFormatContext *s,
yading@11:                                 int stream_index,
yading@11:                                 int64_t pos,
yading@11:                                 int64_t ts_min,
yading@11:                                 int64_t ts,
yading@11:                                 int64_t ts_max,
yading@11:                                 int flags)
yading@11: {
yading@11:     AVSyncPoint *sync, *sp;
yading@11:     AVStream *st;
yading@11:     int i;
yading@11:     int keyframes_to_find = 0;
yading@11:     int64_t curpos;
yading@11:     int64_t step;
yading@11:     int found_lo = 0, found_hi = 0;
yading@11:     int64_t min_distance, distance;
yading@11:     int64_t min_pos = 0;
yading@11:     int first_iter = 1;
yading@11:     AVRational time_base;
yading@11: 
yading@11:     if (flags & AVSEEK_FLAG_BYTE) {
yading@11:         // for byte seeking, we have exact 1:1 "timestamps" - positions
yading@11:         time_base.num = 1;
yading@11:         time_base.den = 1;
yading@11:     } else {
yading@11:         if (stream_index >= 0) {
yading@11:             // we have a reference stream, which time base we use
yading@11:             st = s->streams[stream_index];
yading@11:             time_base = st->time_base;
yading@11:         } else {
yading@11:             // no reference stream, use AV_TIME_BASE as reference time base
yading@11:             time_base.num = 1;
yading@11:             time_base.den = AV_TIME_BASE;
yading@11:         }
yading@11:     }
yading@11: 
yading@11:     // Initialize syncpoint structures for each stream.
yading@11:     sync = av_malloc(s->nb_streams * sizeof(AVSyncPoint));
yading@11:     if (!sync)
yading@11:         // cannot allocate helper structure
yading@11:         return -1;
yading@11: 
yading@11:     for (i = 0; i < s->nb_streams; ++i) {
yading@11:         st = s->streams[i];
yading@11:         sp = &sync[i];
yading@11: 
yading@11:         sp->pos_lo     = INT64_MAX;
yading@11:         sp->ts_lo      = INT64_MAX;
yading@11:         sp->pos_hi     = INT64_MAX;
yading@11:         sp->ts_hi      = INT64_MAX;
yading@11:         sp->terminated = 0;
yading@11:         sp->first_ts   = AV_NOPTS_VALUE;
yading@11:         sp->term_ts    = ts_max;
yading@11:         sp->term_ts_tb = time_base;
yading@11:         sp->last_pos   = pos;
yading@11: 
yading@11:         st->cur_dts    = AV_NOPTS_VALUE;
yading@11: 
yading@11:         if (st->discard < AVDISCARD_ALL)
yading@11:             ++keyframes_to_find;
yading@11:     }
yading@11: 
yading@11:     if (!keyframes_to_find) {
yading@11:         // no stream active, error
yading@11:         av_free(sync);
yading@11:         return -1;
yading@11:     }
yading@11: 
yading@11:     // Find keyframes in all active streams with timestamp/position just before
yading@11:     // and just after requested timestamp/position.
yading@11:     step = s->pb->buffer_size;
yading@11:     curpos = FFMAX(pos - step / 2, 0);
yading@11:     for (;;) {
yading@11:         avio_seek(s->pb, curpos, SEEK_SET);
yading@11:         search_hi_lo_keyframes(s,
yading@11:                                ts, time_base,
yading@11:                                flags,
yading@11:                                sync,
yading@11:                                keyframes_to_find,
yading@11:                                &found_lo, &found_hi,
yading@11:                                first_iter);
yading@11:         if (found_lo == keyframes_to_find && found_hi == keyframes_to_find)
yading@11:             break;  // have all keyframes we wanted
yading@11:         if (!curpos)
yading@11:             break;  // cannot go back anymore
yading@11: 
yading@11:         curpos = pos - step;
yading@11:         if (curpos < 0)
yading@11:             curpos = 0;
yading@11:         step *= 2;
yading@11: 
yading@11:         // switch termination positions
yading@11:         for (i = 0; i < s->nb_streams; ++i) {
yading@11:             st = s->streams[i];
yading@11:             st->cur_dts = AV_NOPTS_VALUE;
yading@11: 
yading@11:             sp = &sync[i];
yading@11:             if (sp->first_ts != AV_NOPTS_VALUE) {
yading@11:                 sp->term_ts    = sp->first_ts;
yading@11:                 sp->term_ts_tb = sp->first_ts_tb;
yading@11:                 sp->first_ts   = AV_NOPTS_VALUE;
yading@11:             }
yading@11:             sp->terminated = 0;
yading@11:             sp->last_pos = curpos;
yading@11:         }
yading@11:         first_iter = 0;
yading@11:     }
yading@11: 
yading@11:     // Find actual position to start decoding so that decoder synchronizes
yading@11:     // closest to ts and between ts_min and ts_max.
yading@11:     pos = INT64_MAX;
yading@11: 
yading@11:     for (i = 0; i < s->nb_streams; ++i) {
yading@11:         st = s->streams[i];
yading@11:         if (st->discard < AVDISCARD_ALL) {
yading@11:             sp = &sync[i];
yading@11:             min_distance = INT64_MAX;
yading@11:             // Find timestamp closest to requested timestamp within min/max limits.
yading@11:             if (sp->pos_lo != INT64_MAX
yading@11:                 && av_compare_ts(ts_min, time_base, sp->ts_lo, st->time_base) <= 0
yading@11:                 && av_compare_ts(sp->ts_lo, st->time_base, ts_max, time_base) <= 0) {
yading@11:                 // low timestamp is in range
yading@11:                 min_distance = ts_distance(ts, time_base, sp->ts_lo, st->time_base);
yading@11:                 min_pos = sp->pos_lo;
yading@11:             }
yading@11:             if (sp->pos_hi != INT64_MAX
yading@11:                 && av_compare_ts(ts_min, time_base, sp->ts_hi, st->time_base) <= 0
yading@11:                 && av_compare_ts(sp->ts_hi, st->time_base, ts_max, time_base) <= 0) {
yading@11:                 // high timestamp is in range, check distance
yading@11:                 distance = ts_distance(sp->ts_hi, st->time_base, ts, time_base);
yading@11:                 if (distance < min_distance) {
yading@11:                     min_distance = distance;
yading@11:                     min_pos = sp->pos_hi;
yading@11:                 }
yading@11:             }
yading@11:             if (min_distance == INT64_MAX) {
yading@11:                 // no timestamp is in range, cannot seek
yading@11:                 av_free(sync);
yading@11:                 return -1;
yading@11:             }
yading@11:             if (min_pos < pos)
yading@11:                 pos = min_pos;
yading@11:         }
yading@11:     }
yading@11: 
yading@11:     avio_seek(s->pb, pos, SEEK_SET);
yading@11:     av_free(sync);
yading@11:     return pos;
yading@11: }
yading@11: 
yading@11: AVParserState *ff_store_parser_state(AVFormatContext *s)
yading@11: {
yading@11:     int i;
yading@11:     AVStream *st;
yading@11:     AVParserStreamState *ss;
yading@11:     AVParserState *state = av_malloc(sizeof(AVParserState));
yading@11:     if (!state)
yading@11:         return NULL;
yading@11: 
yading@11:     state->stream_states = av_malloc(sizeof(AVParserStreamState) * s->nb_streams);
yading@11:     if (!state->stream_states) {
yading@11:         av_free(state);
yading@11:         return NULL;
yading@11:     }
yading@11: 
yading@11:     state->fpos = avio_tell(s->pb);
yading@11: 
yading@11:     // copy context structures
yading@11:     state->packet_buffer                    = s->packet_buffer;
yading@11:     state->parse_queue                      = s->parse_queue;
yading@11:     state->raw_packet_buffer                = s->raw_packet_buffer;
yading@11:     state->raw_packet_buffer_remaining_size = s->raw_packet_buffer_remaining_size;
yading@11: 
yading@11:     s->packet_buffer                        = NULL;
yading@11:     s->parse_queue                          = NULL;
yading@11:     s->raw_packet_buffer                    = NULL;
yading@11:     s->raw_packet_buffer_remaining_size     = RAW_PACKET_BUFFER_SIZE;
yading@11: 
yading@11:     // copy stream structures
yading@11:     state->nb_streams = s->nb_streams;
yading@11:     for (i = 0; i < s->nb_streams; i++) {
yading@11:         st = s->streams[i];
yading@11:         ss = &state->stream_states[i];
yading@11: 
yading@11:         ss->parser        = st->parser;
yading@11:         ss->last_IP_pts   = st->last_IP_pts;
yading@11:         ss->cur_dts       = st->cur_dts;
yading@11:         ss->reference_dts = st->reference_dts;
yading@11:         ss->probe_packets = st->probe_packets;
yading@11: 
yading@11:         st->parser        = NULL;
yading@11:         st->last_IP_pts   = AV_NOPTS_VALUE;
yading@11:         st->cur_dts       = AV_NOPTS_VALUE;
yading@11:         st->reference_dts = AV_NOPTS_VALUE;
yading@11:         st->probe_packets = MAX_PROBE_PACKETS;
yading@11:     }
yading@11: 
yading@11:     return state;
yading@11: }
yading@11: 
yading@11: void ff_restore_parser_state(AVFormatContext *s, AVParserState *state)
yading@11: {
yading@11:     int i;
yading@11:     AVStream *st;
yading@11:     AVParserStreamState *ss;
yading@11:     ff_read_frame_flush(s);
yading@11: 
yading@11:     if (!state)
yading@11:         return;
yading@11: 
yading@11:     avio_seek(s->pb, state->fpos, SEEK_SET);
yading@11: 
yading@11:     // copy context structures
yading@11:     s->packet_buffer                    = state->packet_buffer;
yading@11:     s->parse_queue                      = state->parse_queue;
yading@11:     s->raw_packet_buffer                = state->raw_packet_buffer;
yading@11:     s->raw_packet_buffer_remaining_size = state->raw_packet_buffer_remaining_size;
yading@11: 
yading@11:     // copy stream structures
yading@11:     for (i = 0; i < state->nb_streams; i++) {
yading@11:         st = s->streams[i];
yading@11:         ss = &state->stream_states[i];
yading@11: 
yading@11:         st->parser        = ss->parser;
yading@11:         st->last_IP_pts   = ss->last_IP_pts;
yading@11:         st->cur_dts       = ss->cur_dts;
yading@11:         st->reference_dts = ss->reference_dts;
yading@11:         st->probe_packets = ss->probe_packets;
yading@11:     }
yading@11: 
yading@11:     av_free(state->stream_states);
yading@11:     av_free(state);
yading@11: }
yading@11: 
yading@11: static void free_packet_list(AVPacketList *pktl)
yading@11: {
yading@11:     AVPacketList *cur;
yading@11:     while (pktl) {
yading@11:         cur = pktl;
yading@11:         pktl = cur->next;
yading@11:         av_free_packet(&cur->pkt);
yading@11:         av_free(cur);
yading@11:     }
yading@11: }
yading@11: 
yading@11: void ff_free_parser_state(AVFormatContext *s, AVParserState *state)
yading@11: {
yading@11:     int i;
yading@11:     AVParserStreamState *ss;
yading@11: 
yading@11:     if (!state)
yading@11:         return;
yading@11: 
yading@11:     for (i = 0; i < state->nb_streams; i++) {
yading@11:         ss = &state->stream_states[i];
yading@11:         if (ss->parser)
yading@11:             av_parser_close(ss->parser);
yading@11:     }
yading@11: 
yading@11:     free_packet_list(state->packet_buffer);
yading@11:     free_packet_list(state->parse_queue);
yading@11:     free_packet_list(state->raw_packet_buffer);
yading@11: 
yading@11:     av_free(state->stream_states);
yading@11:     av_free(state);
yading@11: }