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* seek utility functions for use within format handlers
* Copyright (c) 2009 Ivan Schreter
* This file is part of FFmpeg.
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
#include "avformat.h"
* structure to store parser state of one AVStream
typedef struct AVParserStreamState {
// saved members of AVStream
AVCodecParserContext *parser;
AVPacket cur_pkt;
int64_t last_IP_pts;
int64_t cur_dts;
int64_t reference_dts;
const uint8_t *cur_ptr;
int cur_len;
int probe_packets;
} AVParserStreamState;
* structure to store parser state of AVFormat
typedef struct AVParserState {
int64_t fpos; ///< file position at the time of call
// saved members of AVFormatContext
AVStream *cur_st; ///< current stream.
AVPacketList *packet_buffer; ///< packet buffer of original state
AVPacketList *raw_packet_buffer; ///< raw packet buffer of original state
int raw_packet_buffer_remaining_size; ///< remaining space in raw_packet_buffer
// saved info for streams
int nb_streams; ///< number of streams with stored state
AVParserStreamState *stream_states; ///< states of individual streams (array)
} AVParserState;
* Search for the sync point of all active streams.
* This routine is not supposed to be called directly by a user application,
* but by demuxers.
* A sync point is defined as a point in stream, such that, when decoding start
* from this point, the decoded output of all streams synchronizes closest
* to the given timestamp ts. This routine also takes timestamp limits into account.
* Thus, the output will synchronize no sooner than ts_min and no later than ts_max.
* @param stream_index stream index for time base reference of timestamps
* @param pos approximate position where to start searching for key frames
* @param min_ts minimum allowed timestamp (position, if AVSEEK_FLAG_BYTE set)
* @param ts target timestamp (or position, if AVSEEK_FLAG_BYTE set in flags)
* @param max_ts maximum allowed timestamp (position, if AVSEEK_FLAG_BYTE set)
* @param flags if AVSEEK_FLAG_ANY is set, seek to any frame, otherwise only
* to a keyframe. If AVSEEK_FLAG_BYTE is set, search by
* position, not by timestamp.
* @return -1 if no such sync point could be found, otherwise stream position
* (stream is repositioned to this position)
int64_t ff_gen_syncpoint_search(AVFormatContext *s,
int stream_index,
int64_t pos,
int64_t min_ts,
int64_t ts,
int64_t max_ts,
int flags);
* Store current parser state and file position.
* This function can be used by demuxers before a destructive seeking algorithm
* to store the parser state. Depending on the outcome of the seek, either the original
* state can be restored or the new state kept and the original state freed.
* @note As a side effect, the original parser state is reset, since structures
* are relinked to the stored state instead of being deeply-copied (for
* performance reasons and to keep the code simple).
* @param s context from which to save state
* @return parser state object or NULL if memory could not be allocated
AVParserState *ff_store_parser_state(AVFormatContext *s);
* Restore previously saved parser state and file position.
* Saved state will be invalidated and freed by this call, since internal
* structures will be relinked back to the stored state instead of being
* deeply-copied.
* @param s context to which to restore state (same as used for storing state)
* @param state state to restore
void ff_restore_parser_state(AVFormatContext *s, AVParserState *state);
* Free previously saved parser state.
* @param s context to which the state belongs (same as used for storing state)
* @param state state to free
void ff_free_parser_state(AVFormatContext *s, AVParserState *state);
#endif /* AVFORMAT_SEEK_H */