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 AVPacket cur_pkt; 35 int64_t last_IP_pts; 36 int64_t cur_dts; 37 int64_t reference_dts; 38 const uint8_t *cur_ptr; 39 int cur_len; 40 int probe_packets; 41} AVParserStreamState; 42 43/** 44 * structure to store parser state of AVFormat 45 */ 46typedef struct AVParserState { 47 int64_t fpos; ///< file position at the time of call 48 49 // saved members of AVFormatContext 50 AVStream *cur_st; ///< current stream. 51 AVPacketList *packet_buffer; ///< packet buffer of original state 52 AVPacketList *raw_packet_buffer; ///< raw packet buffer of original state 53 int raw_packet_buffer_remaining_size; ///< remaining space in raw_packet_buffer 54 55 // saved info for streams 56 int nb_streams; ///< number of streams with stored state 57 AVParserStreamState *stream_states; ///< states of individual streams (array) 58} AVParserState; 59 60/** 61 * Search for the sync point of all active streams. 62 * 63 * This routine is not supposed to be called directly by a user application, 64 * but by demuxers. 65 * 66 * A sync point is defined as a point in stream, such that, when decoding start 67 * from this point, the decoded output of all streams synchronizes closest 68 * to the given timestamp ts. This routine also takes timestamp limits into account. 69 * Thus, the output will synchronize no sooner than ts_min and no later than ts_max. 70 * 71 * @param stream_index stream index for time base reference of timestamps 72 * @param pos approximate position where to start searching for key frames 73 * @param min_ts minimum allowed timestamp (position, if AVSEEK_FLAG_BYTE set) 74 * @param ts target timestamp (or position, if AVSEEK_FLAG_BYTE set in flags) 75 * @param max_ts maximum allowed timestamp (position, if AVSEEK_FLAG_BYTE set) 76 * @param flags if AVSEEK_FLAG_ANY is set, seek to any frame, otherwise only 77 * to a keyframe. If AVSEEK_FLAG_BYTE is set, search by 78 * position, not by timestamp. 79 * @return -1 if no such sync point could be found, otherwise stream position 80 * (stream is repositioned to this position) 81 */ 82int64_t ff_gen_syncpoint_search(AVFormatContext *s, 83 int stream_index, 84 int64_t pos, 85 int64_t min_ts, 86 int64_t ts, 87 int64_t max_ts, 88 int flags); 89 90/** 91 * Store current parser state and file position. 92 * 93 * This function can be used by demuxers before a destructive seeking algorithm 94 * to store the parser state. Depending on the outcome of the seek, either the original 95 * state can be restored or the new state kept and the original state freed. 96 * 97 * @note As a side effect, the original parser state is reset, since structures 98 * are relinked to the stored state instead of being deeply-copied (for 99 * performance reasons and to keep the code simple). 100 * 101 * @param s context from which to save state 102 * @return parser state object or NULL if memory could not be allocated 103 */ 104AVParserState *ff_store_parser_state(AVFormatContext *s); 105 106/** 107 * Restore previously saved parser state and file position. 108 * 109 * Saved state will be invalidated and freed by this call, since internal 110 * structures will be relinked back to the stored state instead of being 111 * deeply-copied. 112 * 113 * @param s context to which to restore state (same as used for storing state) 114 * @param state state to restore 115 */ 116void ff_restore_parser_state(AVFormatContext *s, AVParserState *state); 117 118/** 119 * Free previously saved parser state. 120 * 121 * @param s context to which the state belongs (same as used for storing state) 122 * @param state state to free 123 */ 124void ff_free_parser_state(AVFormatContext *s, AVParserState *state); 125 126#endif /* AVFORMAT_SEEK_H */ 127