VbrTag.h

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/*
 *      Xing VBR tagging for LAME.
 *
 *      Copyright (c) 1999 A.L. Faber
 *
 * This library 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 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#ifndef LAME_VRBTAG_H
#define LAME_VRBTAG_H


/* -----------------------------------------------------------
 * A Vbr header may be present in the ancillary
 * data field of the first frame of an mp3 bitstream
 * The Vbr header (optionally) contains
 *      frames      total number of audio frames in the bitstream
 *      bytes       total number of bytes in the bitstream
 *      toc         table of contents

 * toc (table of contents) gives seek points
 * for random access
 * the ith entry determines the seek point for
 * i-percent duration
 * seek point in bytes = (toc[i]/256.0) * total_bitstream_bytes
 * e.g. half duration seek point = (toc[50]/256.0) * total_bitstream_bytes
 */


#define FRAMES_FLAG     0x0001
#define BYTES_FLAG      0x0002
#define TOC_FLAG        0x0004
#define VBR_SCALE_FLAG  0x0008

#define NUMTOCENTRIES 100

#define FRAMES_AND_BYTES (FRAMES_FLAG | BYTES_FLAG)



/*structure to receive extracted header */
/* toc may be NULL*/
typedef struct {
    int     h_id;            /* from MPEG header, 0=MPEG2, 1=MPEG1 */
    int     samprate;        /* determined from MPEG header */
    int     flags;           /* from Vbr header data */
    int     frames;          /* total bit stream frames from Vbr header data */
    int     bytes;           /* total bit stream bytes from Vbr header data */
    int     vbr_scale;       /* encoded vbr scale from Vbr header data */
    unsigned char toc[NUMTOCENTRIES]; /* may be NULL if toc not desired */
    int     headersize;      /* size of VBR header, in bytes */
    int     enc_delay;       /* encoder delay */
    int     enc_padding;     /* encoder paddign added at end of stream */
} VBRTAGDATA;

int     CheckVbrTag(unsigned char *buf);
int     GetVbrTag(VBRTAGDATA * pTagData, unsigned char *buf);

int     SeekPoint(unsigned char TOC[NUMTOCENTRIES], int file_bytes, float percent);
int     InitVbrTag(lame_global_flags * gfp);
int     PutVbrTag(lame_global_flags const* gfp, FILE * fid);
int     PutLameVBR(lame_global_flags const* gfp, FILE * fpStream, uint8_t * pbtStreamBuffer,
                   uint32_t id3v2size, uint16_t crc);
void    AddVbrFrame(lame_global_flags * gfp);
void    UpdateMusicCRC(uint16_t * crc, unsigned char *buffer, int size);

#endif

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