PeerStreamer

/*

 * copyright (c) 2001 Fabrice Bellard

 *

 * 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 mpegaudio.h

 * mpeg audio declarations for both encoder and decoder.

 */

#ifndef FFMPEG_MPEGAUDIO_H

#define FFMPEG_MPEGAUDIO_H

#include "avcodec.h"

#include "bitstream.h"

#include "dsputil.h"

/* max frame size, in samples */

#define MPA_FRAME_SIZE 1152

/* max compressed frame size */

#define MPA_MAX_CODED_FRAME_SIZE 1792

#define MPA_MAX_CHANNELS 2

#define SBLIMIT 32 /* number of subbands */

#define MPA_STEREO  0

#define MPA_JSTEREO 1

#define MPA_DUAL    2

#define MPA_MONO    3

/* header + layer + bitrate + freq + lsf/mpeg25 */

#define SAME_HEADER_MASK \

   (0xffe00000 | (3 << 17) | (0xf << 12) | (3 << 10) | (3 << 19))

#define MP3_MASK 0xFFFE0CCF

/* define USE_HIGHPRECISION to have a bit exact (but slower) mpeg

   audio decoder */

#ifdef USE_HIGHPRECISION

#define FRAC_BITS   23   /* fractional bits for sb_samples and dct */

#define WFRAC_BITS  16   /* fractional bits for window */

#else

#define FRAC_BITS   15   /* fractional bits for sb_samples and dct */

#define WFRAC_BITS  14   /* fractional bits for window */

#endif

#define FRAC_ONE    (1 << FRAC_BITS)

#define FIX(a)   ((int)((a) * FRAC_ONE))

#if defined(USE_HIGHPRECISION) && defined(CONFIG_AUDIO_NONSHORT)

typedef int32_t OUT_INT;

#define OUT_MAX INT32_MAX

#define OUT_MIN INT32_MIN

#define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 31)

#else

typedef int16_t OUT_INT;

#define OUT_MAX INT16_MAX

#define OUT_MIN INT16_MIN

#define OUT_SHIFT (WFRAC_BITS + FRAC_BITS - 15)

#endif

#if FRAC_BITS <= 15

typedef int16_t MPA_INT;

#else

typedef int32_t MPA_INT;

#endif

#define BACKSTEP_SIZE 512

#define EXTRABYTES 24

struct GranuleDef;

typedef struct MPADecodeContext {

    DECLARE_ALIGNED_8(uint8_t, last_buf[2*BACKSTEP_SIZE + EXTRABYTES]);

    int last_buf_size;

    int frame_size;

    /* next header (used in free format parsing) */

    uint32_t free_format_next_header;

    int error_protection;

    int layer;

    int sample_rate;

    int sample_rate_index; /* between 0 and 8 */

    int bit_rate;

    GetBitContext gb;

    GetBitContext in_gb;

    int nb_channels;

    int mode;

    int mode_ext;

    int lsf;

    DECLARE_ALIGNED_16(MPA_INT, synth_buf[MPA_MAX_CHANNELS][512 * 2]);

    int synth_buf_offset[MPA_MAX_CHANNELS];

    DECLARE_ALIGNED_16(int32_t, sb_samples[MPA_MAX_CHANNELS][36][SBLIMIT]);

    int32_t mdct_buf[MPA_MAX_CHANNELS][SBLIMIT * 18]; /* previous samples, for layer 3 MDCT */

#ifdef DEBUG

    int frame_count;

#endif

    void (*compute_antialias)(struct MPADecodeContext *s, struct GranuleDef *g);

    int adu_mode; ///< 0 for standard mp3, 1 for adu formatted mp3

    int dither_state;

    int error_resilience;

    AVCodecContext* avctx;

} MPADecodeContext;

/* layer 3 huffman tables */

typedef struct HuffTable {

    int xsize;

    const uint8_t *bits;

    const uint16_t *codes;

} HuffTable;

int ff_mpa_l2_select_table(int bitrate, int nb_channels, int freq, int lsf);

int ff_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate);

void ff_mpa_synth_init(MPA_INT *window);

void ff_mpa_synth_filter(MPA_INT *synth_buf_ptr, int *synth_buf_offset,

                         MPA_INT *window, int *dither_state,

                         OUT_INT *samples, int incr,

                         int32_t sb_samples[SBLIMIT]);

/* fast header check for resync */

static inline int ff_mpa_check_header(uint32_t header){

    /* header */

    if ((header & 0xffe00000) != 0xffe00000)

        return -1;

    /* layer check */

    if ((header & (3<<17)) == 0)

        return -1;

    /* bit rate */

    if ((header & (0xf<<12)) == 0xf<<12)

        return -1;

    /* frequency */

    if ((header & (3<<10)) == 3<<10)

        return -1;

    return 0;

}

#endif /* FFMPEG_MPEGAUDIO_H */