X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavformat%2Fseek.h;h=408f7d6ac7f15a67b49ddc1ed3e2493643eb780b;hb=bba66fc7be8d3c47bc9659ffe9ccd63aea84352f;hp=570c2bcedf5fd586c6d8f8b31799504cb1c01f08;hpb=101036adb9ad143c1da8db41c2dd89eaf6d32deb;p=ffmpeg diff --git a/libavformat/seek.h b/libavformat/seek.h index 570c2bcedf5..408f7d6ac7f 100644 --- a/libavformat/seek.h +++ b/libavformat/seek.h @@ -1,5 +1,5 @@ /* - * Utility functions for seeking for use within FFmpeg format handlers. + * seek utility functions for use within format handlers * * Copyright (c) 2009 Ivan Schreter * @@ -25,30 +25,59 @@ #include "avformat.h" -/// Opaque structure for parser state. -typedef struct AVParserState AVParserState; +/** + * 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 sync point of all active streams. + * Search for the sync point of all active streams. * - * This is not supposed to be called directly by a user application, + * This routine is not supposed to be called directly by a user application, * but by demuxers. * - * A sync point is a point in stream, so that decoding from this point, - * output of decoders of all streams synchronizes closest to given timestamp - * ts (but taking timestamp limits into account, i.e., no sooner than ts_min - * and no later than ts_max). + * 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 < 0 if no such sync point could be found, otherwise stream position - * (stream is repositioned to this position). + * @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, @@ -61,16 +90,16 @@ int64_t ff_gen_syncpoint_search(AVFormatContext *s, /** * Store current parser state and file position. * - * This function can be used by demuxers before destructive seeking algorithm - * to store parser state. After the seek, depending on outcome, original state - * can be restored or new state kept and original state freed. + * 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, original parser state is reset, since structures - * are relinked to stored state instead of being deeply-copied (for - * performance reasons and to keep code simple). + * @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. + * @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); @@ -78,19 +107,19 @@ 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 stored state instead of being + * 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. + * @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. + * @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);