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# frame.h

    00001 /*
    00002  * libmad - MPEG audio decoder library
    00003  * Copyright (C) 2000-2003 Underbit Technologies, Inc.
    00004  *
    00005  * This program is free software; you can redistribute it and/or modify
    00006  * it under the terms of the GNU General Public License as published by
    00007  * the Free Software Foundation; either version 2 of the License, or
    00008  * (at your option) any later version.
    00009  *
    00010  * This program is distributed in the hope that it will be useful,
    00011  * but WITHOUT ANY WARRANTY; without even the implied warranty of
    00012  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    00013  * GNU General Public License for more details.
    00014  *
    00015  * You should have received a copy of the GNU General Public License
    00016  * along with this program; if not, write to the Free Software
    00017  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    00018  *
    00019  * $Id: frame.h,v 1.1 2003/08/31 18:59:46 gabest Exp $
    00020  */
    00021
    00022 # ifndef LIBMAD_FRAME_H
    00023 # define LIBMAD_FRAME_H
    00024
    00025 # include "fixed.h"
    00026 # include "timer.h"
    00027 # include "stream.h"
    00028
    00029 enum mad_layer {
    00030   MAD_LAYER_I   = 1,                    /* Layer I */
    00031   MAD_LAYER_II  = 2,                    /* Layer II */
    00032   MAD_LAYER_III = 3                     /* Layer III */
    00033 };
    00034
    00035 enum mad_mode {
    00036   MAD_MODE_SINGLE_CHANNEL = 0,          /* single channel */
    00037   MAD_MODE_DUAL_CHANNEL   = 1,          /* dual channel */
    00038   MAD_MODE_JOINT_STEREO   = 2,          /* joint (MS/intensity) stereo */
    00039   MAD_MODE_STEREO         = 3           /* normal LR stereo */
    00040 };
    00041
    00042 enum mad_emphasis {
    00043   MAD_EMPHASIS_NONE       = 0,          /* no emphasis */
    00044   MAD_EMPHASIS_50_15_US   = 1,          /* 50/15 microseconds emphasis */
    00045   MAD_EMPHASIS_CCITT_J_17 = 3,          /* CCITT J.17 emphasis */
    00046   MAD_EMPHASIS_RESERVED   = 2           /* unknown emphasis */
    00047 };
    00048
    00049 struct mad_header {
    00050   enum mad_layer layer;                 /* audio layer (1, 2, or 3) */
    00051   enum mad_mode mode;                   /* channel mode (see above) */
    00052   int mode_extension;                   /* additional mode info */
    00053   enum mad_emphasis emphasis;           /* de-emphasis to use (see above) */
    00054
    00055   unsigned long bitrate;                /* stream bitrate (bps) */
    00056   unsigned int samplerate;              /* sampling frequency (Hz) */
    00057
    00058   unsigned short crc_check;             /* frame CRC accumulator */
    00059   unsigned short crc_target;            /* final target CRC checksum */
    00060
    00061   int flags;                            /* flags (see below) */
    00062   int private_bits;                     /* private bits (see below) */
    00063
    00064   mad_timer_t duration;                 /* audio playing time of frame */
    00065 };
    00066
    00067 struct mad_frame {
    00068   struct mad_header header;             /* MPEG audio header */
    00069
    00070   int options;                          /* decoding options (from stream) */
    00071
    00072   mad_fixed_t sbsample[2][36][32];      /* synthesis subband filter samples */
    00073   mad_fixed_t (*overlap)[2][32][18];    /* Layer III block overlap data */
    00074 };
    00075
    00076 # define MAD_NCHANNELS(header)          ((header)->mode ? 2 : 1)
    00077 # define MAD_NSBSAMPLES(header)  \
    00078   ((header)->layer == MAD_LAYER_I ? 12 :  \
    00079    (((header)->layer == MAD_LAYER_III &&  \
    00080      ((header)->flags & MAD_FLAG_LSF_EXT)) ? 18 : 36))
    00081
    00082 enum {
    00083   MAD_FLAG_NPRIVATE_III = 0x0007,       /* number of Layer III private bits */
    00084   MAD_FLAG_INCOMPLETE   = 0x0008,       /* header but not data is decoded */
    00085
    00086   MAD_FLAG_PROTECTION   = 0x0010,       /* frame has CRC protection */
    00087   MAD_FLAG_COPYRIGHT    = 0x0020,       /* frame is copyright */
    00088   MAD_FLAG_ORIGINAL     = 0x0040,       /* frame is original (else copy) */
    00089   MAD_FLAG_PADDING      = 0x0080,       /* frame has additional slot */
    00090
    00091   MAD_FLAG_I_STEREO     = 0x0100,       /* uses intensity joint stereo */
    00092   MAD_FLAG_MS_STEREO    = 0x0200,       /* uses middle/side joint stereo */
    00093   MAD_FLAG_FREEFORMAT   = 0x0400,       /* uses free format bitrate */
    00094
    00095   MAD_FLAG_LSF_EXT      = 0x1000,       /* lower sampling freq. extension */
    00096   MAD_FLAG_MC_EXT       = 0x2000,       /* multichannel audio extension */
    00097   MAD_FLAG_MPEG_2_5_EXT = 0x4000        /* MPEG 2.5 (unofficial) extension */
    00098 };
    00099
    00100 enum {
    00101   MAD_PRIVATE_HEADER    = 0x0100,       /* header private bit */
    00102   MAD_PRIVATE_III       = 0x001f        /* Layer III private bits (up to 5) */
    00103 };
    00104
    00105 void mad_header_init(struct mad_header *);
    00106
    00107 # define mad_header_finish(header)  /* nothing */
    00108
    00109 int mad_header_decode(struct mad_header *, struct mad_stream *);
    00110
    00111 void mad_frame_init(struct mad_frame *);
    00112 void mad_frame_finish(struct mad_frame *);
    00113
    00114 int mad_frame_decode(struct mad_frame *, struct mad_stream *);
    00115
    00116 void mad_frame_mute(struct mad_frame *);
    00117
    00118 # endif