frame.h

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/*
 * libmad - MPEG audio decoder library
 * Copyright (C) 2000-2004 Underbit Technologies, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * $Id: frame.h,v 1.20 2004/01/23 09:41:32 rob Exp $
 */

# ifndef LIBMAD_FRAME_H
# define LIBMAD_FRAME_H
 
# include "fixed.h"
# include "timer.h"
# include "stream.h"
 
enum mad_layer {
  MAD_LAYER_I   = 1,            /* Layer I */
  MAD_LAYER_II  = 2,            /* Layer II */
  MAD_LAYER_III = 3         /* Layer III */
};
 
enum mad_mode {
  MAD_MODE_SINGLE_CHANNEL = 0,      /* single channel */
  MAD_MODE_DUAL_CHANNEL   = 1,      /* dual channel */
  MAD_MODE_JOINT_STEREO   = 2,      /* joint (MS/intensity) stereo */
  MAD_MODE_STEREO     = 3       /* normal LR stereo */
};
 
enum mad_emphasis {
  MAD_EMPHASIS_NONE   = 0,      /* no emphasis */
  MAD_EMPHASIS_50_15_US   = 1,      /* 50/15 microseconds emphasis */
  MAD_EMPHASIS_CCITT_J_17 = 3,      /* CCITT J.17 emphasis */
  MAD_EMPHASIS_RESERVED   = 2       /* unknown emphasis */
};
 
struct mad_header {
  enum mad_layer layer;         /* audio layer (1, 2, or 3) */
  enum mad_mode mode;           /* channel mode (see above) */
  int mode_extension;           /* additional mode info */
  enum mad_emphasis emphasis;       /* de-emphasis to use (see above) */
 
  unsigned long bitrate;        /* stream bitrate (bps) */
  unsigned int samplerate;      /* sampling frequency (Hz) */
 
  unsigned short crc_check;     /* frame CRC accumulator */
  unsigned short crc_target;        /* final target CRC checksum */
 
  int flags;                /* flags (see below) */
  int private_bits;         /* private bits (see below) */
 
  mad_timer_t duration;         /* audio playing time of frame */
};
 
struct mad_frame {
  struct mad_header header;     /* MPEG audio header */
 
  int options;              /* decoding options (from stream) */
 
  mad_fixed_t sbsample[2][36][32];  /* synthesis subband filter samples */
  mad_fixed_t (*overlap)[2][32][18];    /* Layer III block overlap data */
};
 
# define MAD_NCHANNELS(header)      ((header)->mode ? 2 : 1)
# define MAD_NSBSAMPLES(header)  \
  ((header)->layer == MAD_LAYER_I ? 12 :  \
   (((header)->layer == MAD_LAYER_III &&  \
     ((header)->flags & MAD_FLAG_LSF_EXT)) ? 18 : 36))
 
enum {
  MAD_FLAG_NPRIVATE_III = 0x0007,   /* number of Layer III private bits */
  MAD_FLAG_INCOMPLETE   = 0x0008,   /* header but not data is decoded */
 
  MAD_FLAG_PROTECTION   = 0x0010,   /* frame has CRC protection */
  MAD_FLAG_COPYRIGHT    = 0x0020,   /* frame is copyright */
  MAD_FLAG_ORIGINAL = 0x0040,   /* frame is original (else copy) */
  MAD_FLAG_PADDING  = 0x0080,   /* frame has additional slot */
 
  MAD_FLAG_I_STEREO = 0x0100,   /* uses intensity joint stereo */
  MAD_FLAG_MS_STEREO    = 0x0200,   /* uses middle/side joint stereo */
  MAD_FLAG_FREEFORMAT   = 0x0400,   /* uses free format bitrate */
 
  MAD_FLAG_LSF_EXT  = 0x1000,   /* lower sampling freq. extension */
  MAD_FLAG_MC_EXT   = 0x2000,   /* multichannel audio extension */
  MAD_FLAG_MPEG_2_5_EXT = 0x4000    /* MPEG 2.5 (unofficial) extension */
};
 
enum {
  MAD_PRIVATE_HEADER    = 0x0100,   /* header private bit */
  MAD_PRIVATE_III   = 0x001f    /* Layer III private bits (up to 5) */
};
 
void mad_header_init(struct mad_header *);
 
# define mad_header_finish(header)  /* nothing */
 
int mad_header_decode(struct mad_header *, struct mad_stream *);
 
void mad_frame_init(struct mad_frame *);
void mad_frame_finish(struct mad_frame *);
 
int mad_frame_decode(struct mad_frame *, struct mad_stream *);
 
void mad_frame_mute(struct mad_frame *);
 
# endif