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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 | */ | |
31 | typedef 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 | */ | |
42 | typedef 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 | */ | |
78 | int64_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 | */ | |
100 | AVParserState *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 | */ | |
112 | void 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 | */ | |
120 | void ff_free_parser_state(AVFormatContext *s, AVParserState *state); | |
121 | ||
122 | #endif /* AVFORMAT_SEEK_H */ |