FFmpeg/libavcodec/vorbis_parser.h

/*
 * Copyright (c) 2012 Justin Ruggles
 *
 * 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
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * 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
 */

/**
 * @file
 * Vorbis audio parser
 *
 * Determines the duration for each packet.
 */

#ifndef AVCODEC_VORBIS_PARSER_H
#define AVCODEC_VORBIS_PARSER_H

#include "avcodec.h"

typedef struct VorbisParseContext {
    AVCodecContext *avctx;      ///< codec context
    int extradata_parsed;       ///< we have attempted to parse extradata
    int valid_extradata;        ///< extradata is valid, so we can calculate duration
    int blocksize[2];           ///< short and long window sizes
    int previous_blocksize;     ///< previous window size
    int mode_blocksize[64];     ///< window size mapping for each mode
    int mode_count;             ///< number of modes
    int mode_mask;              ///< bitmask used to get the mode in each packet
    int prev_mask;              ///< bitmask used to get the previous mode flag in each packet
} VorbisParseContext;

/**
 * Initialize the Vorbis parser using headers in the extradata.
 *
 * @param avctx codec context
 * @param s     Vorbis parser context
 */
int avpriv_vorbis_parse_extradata(AVCodecContext *avctx, VorbisParseContext *s);

#define VORBIS_FLAG_HEADER  0x00000001
#define VORBIS_FLAG_COMMENT 0x00000002

/**
 * Get the duration for a Vorbis packet.
 *
 * avpriv_vorbis_parse_extradata() must have been successfully called prior to
 * this in order for a correct duration to be returned. If @p flags is @c NULL,
 * special frames are considered invalid.
 *
 * @param s        Vorbis parser context
 * @param buf      buffer containing a Vorbis frame
 * @param buf_size size of the buffer
 * @param flags    flags for special frames
 */
int avpriv_vorbis_parse_frame_flags(VorbisParseContext *s, const uint8_t *buf,
                                    int buf_size, int *flags);

/**
 * Get the duration for a Vorbis packet.
 *
 * avpriv_vorbis_parse_extradata() must have been successfully called prior to
 * this in order for a correct duration to be returned.
 *
 * @param s        Vorbis parser context
 * @param buf      buffer containing a Vorbis frame
 * @param buf_size size of the buffer
 */
int avpriv_vorbis_parse_frame(VorbisParseContext *s, const uint8_t *buf,
                              int buf_size);

void avpriv_vorbis_parse_reset(VorbisParseContext *s);

#endif /* AVCODEC_VORBIS_PARSER_H */