1/* 2 * seek utility functions for use within format handlers 3 * 4 * Copyright (c) 2009 Ivan Schreter 5 * 6 * This file is part of FFmpeg. 7 * 8 * FFmpeg is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU Lesser General Public 10 * License as published by the Free Software Foundation; either 11 * version 2.1 of the License, or (at your option) any later version. 12 * 13 * FFmpeg is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 16 * Lesser General Public License for more details. 17 * 18 * You should have received a copy of the GNU Lesser General Public 19 * License along with FFmpeg; if not, write to the Free Software 20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 21 */ 22 23#ifndef AVFORMAT_SEEK_H 24#define AVFORMAT_SEEK_H 25 26#include "avformat.h" 27 28/** 29 * structure to store parser state of one AVStream 30 */ 31typedef struct AVParserStreamState { 32 // saved members of AVStream 33 AVCodecParserContext *parser; 34 int64_t last_IP_pts; 35 int64_t cur_dts; 36 int probe_packets; 37} AVParserStreamState; 38 39/** 40 * structure to store parser state of AVFormat 41 */ 42typedef struct AVParserState { 43 int64_t fpos; ///< file position at the time of call 44 45 // saved members of AVFormatContext 46 AVPacketList *packet_buffer; ///< packet buffer of original state 47 AVPacketList *parse_queue; ///< parse queue of original state 48 AVPacketList *raw_packet_buffer; ///< raw packet buffer of original state 49 int raw_packet_buffer_remaining_size; ///< remaining space in raw_packet_buffer 50 51 // saved info for streams 52 int nb_streams; ///< number of streams with stored state 53 AVParserStreamState *stream_states; ///< states of individual streams (array) 54} AVParserState; 55 56/** 57 * Search for the sync point of all active streams. 58 * 59 * This routine is not supposed to be called directly by a user application, 60 * but by demuxers. 61 * 62 * A sync point is defined as a point in stream, such that, when decoding start 63 * from this point, the decoded output of all streams synchronizes closest 64 * to the given timestamp ts. This routine also takes timestamp limits into account. 65 * Thus, the output will synchronize no sooner than ts_min and no later than ts_max. 66 * 67 * @param stream_index stream index for time base reference of timestamps 68 * @param pos approximate position where to start searching for key frames 69 * @param min_ts minimum allowed timestamp (position, if AVSEEK_FLAG_BYTE set) 70 * @param ts target timestamp (or position, if AVSEEK_FLAG_BYTE set in flags) 71 * @param max_ts maximum allowed timestamp (position, if AVSEEK_FLAG_BYTE set) 72 * @param flags if AVSEEK_FLAG_ANY is set, seek to any frame, otherwise only 73 * to a keyframe. If AVSEEK_FLAG_BYTE is set, search by 74 * position, not by timestamp. 75 * @return -1 if no such sync point could be found, otherwise stream position 76 * (stream is repositioned to this position) 77 */ 78int64_t ff_gen_syncpoint_search(AVFormatContext *s, 79 int stream_index, 80 int64_t pos, 81 int64_t min_ts, 82 int64_t ts, 83 int64_t max_ts, 84 int flags); 85 86/** 87 * Store current parser state and file position. 88 * 89 * This function can be used by demuxers before a destructive seeking algorithm 90 * to store the parser state. Depending on the outcome of the seek, either the original 91 * state can be restored or the new state kept and the original state freed. 92 * 93 * @note As a side effect, the original parser state is reset, since structures 94 * are relinked to the stored state instead of being deeply-copied (for 95 * performance reasons and to keep the code simple). 96 * 97 * @param s context from which to save state 98 * @return parser state object or NULL if memory could not be allocated 99 */ 100AVParserState *ff_store_parser_state(AVFormatContext *s); 101 102/** 103 * Restore previously saved parser state and file position. 104 * 105 * Saved state will be invalidated and freed by this call, since internal 106 * structures will be relinked back to the stored state instead of being 107 * deeply-copied. 108 * 109 * @param s context to which to restore state (same as used for storing state) 110 * @param state state to restore 111 */ 112void ff_restore_parser_state(AVFormatContext *s, AVParserState *state); 113 114/** 115 * Free previously saved parser state. 116 * 117 * @param s context to which the state belongs (same as used for storing state) 118 * @param state state to free 119 */ 120void ff_free_parser_state(AVFormatContext *s, AVParserState *state); 121 122#endif /* AVFORMAT_SEEK_H */ 123