apedec.c

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/*
 * Monkey's Audio lossless audio decoder
 * Copyright (c) 2007 Benjamin Zores <[e-mail]>
 *  based upon libdemac from Dave Chapman.
 *
 * 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
 */

#define ALT_BITSTREAM_READER_LE
#include "avcodec.h"
#include "dsputil.h"
#include "bitstream.h"
#include "bytestream.h"
#undef memcpy
#define memcpy uc_memcpy
/**
 * @file apedec.c
 * Monkey's Audio lossless audio decoder
 */

#define BLOCKS_PER_LOOP     4608
#define MAX_CHANNELS        2
#define MAX_BYTESPERSAMPLE  3

#define APE_FRAMECODE_MONO_SILENCE    1
#define APE_FRAMECODE_STEREO_SILENCE  3
#define APE_FRAMECODE_PSEUDO_STEREO   4

#define HISTORY_SIZE 512
#define PREDICTOR_ORDER 8
/** Total size of all predictor histories */
#define PREDICTOR_SIZE 50

#define YDELAYA (18 + PREDICTOR_ORDER*4)
#define YDELAYB (18 + PREDICTOR_ORDER*3)
#define XDELAYA (18 + PREDICTOR_ORDER*2)
#define XDELAYB (18 + PREDICTOR_ORDER)

#define YADAPTCOEFFSA 18
#define XADAPTCOEFFSA 14
#define YADAPTCOEFFSB 10
#define XADAPTCOEFFSB 5

/**
 * Possible compression levels
 * @{
 */
enum APECompressionLevel {
    COMPRESSION_LEVEL_FAST       = 1000,
    COMPRESSION_LEVEL_NORMAL     = 2000,
    COMPRESSION_LEVEL_HIGH       = 3000,
    COMPRESSION_LEVEL_EXTRA_HIGH = 4000,
    COMPRESSION_LEVEL_INSANE     = 5000
};
/** @} */

#define APE_FILTER_LEVELS 3

/** Filter orders depending on compression level */
static const uint16_t ape_filter_orders[5][APE_FILTER_LEVELS] = {
    {  0,   0,    0 },
    { 16,   0,    0 },
    { 64,   0,    0 },
    { 32, 256,    0 },
    { 16, 256, 1280 }
};

/** Filter fraction bits depending on compression level */
static const uint16_t ape_filter_fracbits[5][APE_FILTER_LEVELS] = {
    {  0,  0,  0 },
    { 11,  0,  0 },
    { 11,  0,  0 },
    { 10, 13,  0 },
    { 11, 13, 15 }
};


/** Filters applied to the decoded data */
typedef struct APEFilter {
    int16_t *coeffs;        ///< actual coefficients used in filtering
    int16_t *adaptcoeffs;   ///< adaptive filter coefficients used for correcting of actual filter coefficients
    int16_t *historybuffer; ///< filter memory
    int16_t *delay;         ///< filtered values

    int avg;
} APEFilter;

typedef struct APERice {
    uint32_t k;
    uint32_t ksum;
} APERice;

typedef struct APERangecoder {
    uint32_t low;           ///< low end of interval
    uint32_t range;         ///< length of interval
    uint32_t help;          ///< bytes_to_follow resp. intermediate value
    unsigned int buffer;    ///< buffer for input/output
} APERangecoder;

/** Filter histories */
typedef struct APEPredictor {
    int32_t *buf;

    int32_t lastA[2];

    int32_t filterA[2];
    int32_t filterB[2];

    int32_t coeffsA[2][4];  ///< adaption coefficients
    int32_t coeffsB[2][5];  ///< adaption coefficients
    int32_t historybuffer[HISTORY_SIZE + PREDICTOR_SIZE];
} APEPredictor;

/** Decoder context */
typedef struct APEContext {
    AVCodecContext *avctx;
    DSPContext dsp;
    int channels;
    int samples;                             ///< samples left to decode in current frame

    int fileversion;                         ///< codec version, very important in decoding process
    int compression_level;                   ///< compression levels
    int fset;                                ///< which filter set to use (calculated from compression level)
    int flags;                               ///< global decoder flags

    uint32_t CRC;                            ///< frame CRC
    int frameflags;                          ///< frame flags
    int currentframeblocks;                  ///< samples (per channel) in current frame
    int blocksdecoded;                       ///< count of decoded samples in current frame
    APEPredictor predictor;                  ///< predictor used for final reconstruction

    int32_t decoded0[BLOCKS_PER_LOOP];       ///< decoded data for the first channel
    int32_t decoded1[BLOCKS_PER_LOOP];       ///< decoded data for the second channel

    int16_t* filterbuf[APE_FILTER_LEVELS];   ///< filter memory

    APERangecoder rc;                        ///< rangecoder used to decode actual values
    APERice riceX;                           ///< rice code parameters for the second channel
    APERice riceY;                           ///< rice code parameters for the first channel
    APEFilter filters[APE_FILTER_LEVELS][2]; ///< filters used for reconstruction

    uint8_t *data;                           ///< current frame data
    uint8_t *data_end;                       ///< frame data end
    uint8_t *ptr;                            ///< current position in frame data
    uint8_t *last_ptr;                       ///< position where last 4608-sample block ended
} APEContext;

// TODO: dsputilize
static inline void vector_add(int16_t * v1, int16_t * v2, int order)
{
    while (order--)
       *v1++ += *v2++;
}

// TODO: dsputilize
static inline void vector_sub(int16_t * v1, int16_t * v2, int order)
{
    while (order--)
        *v1++ -= *v2++;
}

// TODO: dsputilize
static inline int32_t scalarproduct(int16_t * v1, int16_t * v2, int order)
{
    int res = 0;

    while (order--)
        res += *v1++ * *v2++;

    return res;
}

static int ape_decode_init(AVCodecContext * avctx)
{
    APEContext *s = avctx->priv_data;
    int i;

    if (avctx->extradata_size != 6) {
        av_log(avctx, AV_LOG_ERROR, "Incorrect extradata\n");
        return -1;
    }
    if (avctx->bits_per_sample != 16) {
        av_log(avctx, AV_LOG_ERROR, "Only 16-bit samples are supported\n");
        return -1;
    }
    if (avctx->channels > 2) {
        av_log(avctx, AV_LOG_ERROR, "Only mono and stereo is supported\n");
        return -1;
    }
    s->avctx             = avctx;
    s->channels          = avctx->channels;
    s->fileversion       = AV_RL16(avctx->extradata);
    s->compression_level = AV_RL16(avctx->extradata + 2);
    s->flags             = AV_RL16(avctx->extradata + 4);

    av_log(avctx, AV_LOG_DEBUG, "Compression Level: %d - Flags: %d\n", s->compression_level, s->flags);
    if (s->compression_level % 1000 || s->compression_level > COMPRESSION_LEVEL_INSANE) {
        av_log(avctx, AV_LOG_ERROR, "Incorrect compression level %d\n", s->compression_level);
        return -1;
    }
    s->fset = s->compression_level / 1000 - 1;
    for (i = 0; i < APE_FILTER_LEVELS; i++) {
        if (!ape_filter_orders[s->fset][i])
            break;
        s->filterbuf[i] = av_malloc((ape_filter_orders[s->fset][i] * 3 + HISTORY_SIZE) * 4);
    }

    dsputil_init(&s->dsp, avctx);
    return 0;
}

static int ape_decode_close(AVCodecContext * avctx)
{
    APEContext *s = avctx->priv_data;
    int i;

    for (i = 0; i < APE_FILTER_LEVELS; i++)
        av_freep(&s->filterbuf[i]);

    return 0;
}

/**
 * @defgroup rangecoder APE range decoder
 * @{
 */

#define CODE_BITS    32
#define TOP_VALUE    ((unsigned int)1 << (CODE_BITS-1))
#define SHIFT_BITS   (CODE_BITS - 9)
#define EXTRA_BITS   ((CODE_BITS-2) % 8 + 1)
#define BOTTOM_VALUE (TOP_VALUE >> 8)

/** Start the decoder */
static inline void range_start_decoding(APEContext * ctx)
{
    ctx->rc.buffer = bytestream_get_byte(&ctx->ptr);
    ctx->rc.low    = ctx->rc.buffer >> (8 - EXTRA_BITS);
    ctx->rc.range  = (uint32_t) 1 << EXTRA_BITS;
}

/** Perform normalization */
static inline void range_dec_normalize(APEContext * ctx)
{
    while (ctx->rc.range <= BOTTOM_VALUE) {
        ctx->rc.buffer = (ctx->rc.buffer << 8) | bytestream_get_byte(&ctx->ptr);
        ctx->rc.low    = (ctx->rc.low << 8)    | ((ctx->rc.buffer >> 1) & 0xFF);
        ctx->rc.range  <<= 8;
    }
}

/**
 * Calculate culmulative frequency for next symbol. Does NO update!
 * @param tot_f is the total frequency or (code_value)1<<shift
 * @return the culmulative frequency
 */
static inline int range_decode_culfreq(APEContext * ctx, int tot_f)
{
    range_dec_normalize(ctx);
    ctx->rc.help = ctx->rc.range / tot_f;
    return ctx->rc.low / ctx->rc.help;
}

/**
 * Decode value with given size in bits
 * @param shift number of bits to decode
 */
static inline int range_decode_culshift(APEContext * ctx, int shift)
{
    range_dec_normalize(ctx);
    ctx->rc.help = ctx->rc.range >> shift;
    return ctx->rc.low / ctx->rc.help;
}


/**
 * Update decoding state
 * @param sy_f the interval length (frequency of the symbol)
 * @param lt_f the lower end (frequency sum of < symbols)
 */
static inline void range_decode_update(APEContext * ctx, int sy_f, int lt_f)
{
    ctx->rc.low  -= ctx->rc.help * lt_f;
    ctx->rc.range = ctx->rc.help * sy_f;
}

/** Decode n bits (n <= 16) without modelling */
static inline int range_decode_bits(APEContext * ctx, int n)
{
    int sym = range_decode_culshift(ctx, n);
    range_decode_update(ctx, 1, sym);
    return sym;
}


#define MODEL_ELEMENTS 64

/**
 * Fixed probabilities for symbols in Monkey Audio version 3.97
 */
static const uint32_t counts_3970[65] = {
        0, 14824, 28224, 39348, 47855, 53994, 58171, 60926,
    62682, 63786, 64463, 64878, 65126, 65276, 65365, 65419,
    65450, 65469, 65480, 65487, 65491, 65493, 65494, 65495,
    65496, 65497, 65498, 65499, 65500, 65501, 65502, 65503,
    65504, 65505, 65506, 65507, 65508, 65509, 65510, 65511,
    65512, 65513, 65514, 65515, 65516, 65517, 65518, 65519,
    65520, 65521, 65522, 65523, 65524, 65525, 65526, 65527,
    65528, 65529, 65530, 65531, 65532, 65533, 65534, 65535,
    65536
};

/**
 * Probability ranges for symbols in Monkey Audio version 3.97
 */
static const uint16_t counts_diff_3970[64] = {
    14824, 13400, 11124, 8507, 6139, 4177, 2755, 1756,
    1104, 677, 415, 248, 150, 89, 54, 31,
    19, 11, 7, 4, 2, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1
};

/**
 * Fixed probabilities for symbols in Monkey Audio version 3.98
 */
static const uint32_t counts_3980[65] = {
        0, 19578, 36160, 48417, 56323, 60899, 63265, 64435,
    64971, 65232, 65351, 65416, 65447, 65466, 65476, 65482,
    65485, 65488, 65490, 65491, 65492, 65493, 65494, 65495,
    65496, 65497, 65498, 65499, 65500, 65501, 65502, 65503,
    65504, 65505, 65506, 65507, 65508, 65509, 65510, 65511,
    65512, 65513, 65514, 65515, 65516, 65517, 65518, 65519,
    65520, 65521, 65522, 65523, 65524, 65525, 65526, 65527,
    65528, 65529, 65530, 65531, 65532, 65533, 65534, 65535,
    65536
};

/**
 * Probability ranges for symbols in Monkey Audio version 3.98
 */
static const uint16_t counts_diff_3980[64] = {
    19578, 16582, 12257, 7906, 4576, 2366, 1170, 536,
    261, 119, 65, 31, 19, 10, 6, 3,
    3, 2, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1
};

/**
 * Decode symbol
 * @param counts probability range start position
 * @param count_diffs probability range widths
 */
static inline int range_get_symbol(APEContext * ctx,
                                   const uint32_t counts[],
                                   const uint16_t counts_diff[])
{
    int symbol, cf;

    cf = range_decode_culshift(ctx, 16);

    /* figure out the symbol inefficiently; a binary search would be much better */
    for (symbol = 0; counts[symbol + 1] <= cf; symbol++);

    range_decode_update(ctx, counts_diff[symbol], counts[symbol]);

    return symbol;
}
/** @} */ // group rangecoder

static inline void update_rice(APERice *rice, int x)
{
    rice->ksum += ((x + 1) / 2) - ((rice->ksum + 16) >> 5);

    if (rice->k == 0)
        rice->k = 1;
    else if (rice->ksum < (1 << (rice->k + 4)))
        rice->k--;
    else if (rice->ksum >= (1 << (rice->k + 5)))
        rice->k++;
}

static inline int ape_decode_value(APEContext * ctx, APERice *rice)
{
    int x, overflow;

    if (ctx->fileversion < 3980) {
        int tmpk;

        overflow = range_get_symbol(ctx, counts_3970, counts_diff_3970);

        if (overflow == (MODEL_ELEMENTS - 1)) {
            tmpk = range_decode_bits(ctx, 5);
            overflow = 0;
        } else
            tmpk = (rice->k < 1) ? 0 : rice->k - 1;

        if (tmpk <= 16)
            x = range_decode_bits(ctx, tmpk);
        else {
            x = range_decode_bits(ctx, 16);
            x |= (range_decode_bits(ctx, tmpk - 16) << 16);
        }
        x += overflow << tmpk;
    } else {
        int base, pivot;

        pivot = rice->ksum >> 5;
        if (pivot == 0)
            pivot = 1;

        overflow = range_get_symbol(ctx, counts_3980, counts_diff_3980);

        if (overflow == (MODEL_ELEMENTS - 1)) {
            overflow  = range_decode_bits(ctx, 16) << 16;
            overflow |= range_decode_bits(ctx, 16);
        }

        base = range_decode_culfreq(ctx, pivot);
        range_decode_update(ctx, 1, base);

        x = base + overflow * pivot;
    }

    update_rice(rice, x);

    /* Convert to signed */
    if (x & 1)
        return (x >> 1) + 1;
    else
        return -(x >> 1);
}

static void entropy_decode(APEContext * ctx, int blockstodecode, int stereo)
{
    int32_t *decoded0 = ctx->decoded0;
    int32_t *decoded1 = ctx->decoded1;

    ctx->blocksdecoded = blockstodecode;

    if (ctx->frameflags & APE_FRAMECODE_STEREO_SILENCE) {