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/libavformat/seek.h

http://github.com/FFmpeg/FFmpeg
C++ Header | 123 lines | 30 code | 11 blank | 82 comment | 0 complexity | 5e12bb4ece0de03df04b7f78e34f347c MD5 | raw file
  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    int64_t                 reference_dts;
 37    int                     probe_packets;
 38} AVParserStreamState;
 39
 40/**
 41 * structure to store parser state of AVFormat
 42 */
 43typedef struct AVParserState {
 44    int64_t         fpos;                   ///< file position at the time of call
 45
 46    // saved members of AVFormatContext
 47    AVPacketList   *packet_buffer;          ///< packet buffer of original state
 48    AVPacketList   *parse_queue;            ///< parse queue of original state
 49    AVPacketList   *raw_packet_buffer;      ///< raw packet buffer of original state
 50    int raw_packet_buffer_remaining_size;   ///< remaining space in raw_packet_buffer
 51
 52    // saved info for streams
 53    int                  nb_streams;        ///< number of streams with stored state
 54    AVParserStreamState *stream_states;     ///< states of individual streams (array)
 55} AVParserState;
 56
 57/**
 58 * Search for the sync point of all active streams.
 59 *
 60 * This routine is not supposed to be called directly by a user application,
 61 * but by demuxers.
 62 *
 63 * A sync point is defined as a point in stream, such that, when decoding start
 64 * from this point, the decoded output of all streams synchronizes closest
 65 * to the given timestamp ts. This routine also takes timestamp limits into account.
 66 * Thus, the output will synchronize no sooner than ts_min and no later than ts_max.
 67 *
 68 * @param stream_index stream index for time base reference of timestamps
 69 * @param pos          approximate position where to start searching for key frames
 70 * @param min_ts       minimum allowed timestamp (position, if AVSEEK_FLAG_BYTE set)
 71 * @param ts           target timestamp (or position, if AVSEEK_FLAG_BYTE set in flags)
 72 * @param max_ts       maximum allowed timestamp (position, if AVSEEK_FLAG_BYTE set)
 73 * @param flags        if AVSEEK_FLAG_ANY is set, seek to any frame, otherwise only
 74 *                     to a keyframe. If AVSEEK_FLAG_BYTE is set, search by
 75 *                     position, not by timestamp.
 76 * @return -1 if no such sync point could be found, otherwise stream position
 77 *                     (stream is repositioned to this position)
 78 */
 79int64_t ff_gen_syncpoint_search(AVFormatContext *s,
 80                                int stream_index,
 81                                int64_t pos,
 82                                int64_t min_ts,
 83                                int64_t ts,
 84                                int64_t max_ts,
 85                                int flags);
 86
 87/**
 88 * Store current parser state and file position.
 89 *
 90 * This function can be used by demuxers before a destructive seeking algorithm
 91 * to store the parser state. Depending on the outcome of the seek, either the original
 92 * state can be restored or the new state kept and the original state freed.
 93 *
 94 * @note As a side effect, the original parser state is reset, since structures
 95 *       are relinked to the stored state instead of being deeply-copied (for
 96 *       performance reasons and to keep the code simple).
 97 *
 98 * @param s context from which to save state
 99 * @return parser state object or NULL if memory could not be allocated
100 */
101AVParserState *ff_store_parser_state(AVFormatContext *s);
102
103/**
104 * Restore previously saved parser state and file position.
105 *
106 * Saved state will be invalidated and freed by this call, since internal
107 * structures will be relinked back to the stored state instead of being
108 * deeply-copied.
109 *
110 * @param s     context to which to restore state (same as used for storing state)
111 * @param state state to restore
112 */
113void ff_restore_parser_state(AVFormatContext *s, AVParserState *state);
114
115/**
116 * Free previously saved parser state.
117 *
118 * @param s     context to which the state belongs (same as used for storing state)
119 * @param state state to free
120 */
121void ff_free_parser_state(AVFormatContext *s, AVParserState *state);
122
123#endif /* AVFORMAT_SEEK_H */