wavpack.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

/*
 * WavPack lossless audio decoder
 * Copyright (c) 2006 Konstantin Shishkov
 *
 * 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 "bitstream.h"
#include "unary.h"

/**
 * @file wavpack.c
 * WavPack lossless audio decoder
 */

#define WV_JOINT_STEREO 0x00000010
#define WV_FALSE_STEREO 0x40000000

enum WP_ID_Flags{
    WP_IDF_MASK   = 0x1F,
    WP_IDF_IGNORE = 0x20,
    WP_IDF_ODD    = 0x40,
    WP_IDF_LONG   = 0x80
};

enum WP_ID{
    WP_ID_DUMMY = 0,
    WP_ID_ENCINFO,
    WP_ID_DECTERMS,
    WP_ID_DECWEIGHTS,
    WP_ID_DECSAMPLES,
    WP_ID_ENTROPY,
    WP_ID_HYBRID,
    WP_ID_SHAPING,
    WP_ID_FLOATINFO,
    WP_ID_INT32INFO,
    WP_ID_DATA,
    WP_ID_CORR,
    WP_ID_FLT,
    WP_ID_CHANINFO
};

#define MAX_TERMS 16

typedef struct Decorr {
    int delta;
    int value;
    int weightA;
    int weightB;
    int samplesA[8];
    int samplesB[8];
} Decorr;

typedef struct WavpackContext {
    AVCodecContext *avctx;
    int stereo, stereo_in;
    int joint;
    uint32_t CRC;
    GetBitContext gb;
    int data_size; // in bits
    int samples;
    int median[6];
    int terms;
    Decorr decorr[MAX_TERMS];
    int zero, one, zeroes;
    int and, or, shift;
} WavpackContext;

// exponent table copied from WavPack source
static const uint8_t wp_exp2_table [256] = {
    0x00, 0x01, 0x01, 0x02, 0x03, 0x03, 0x04, 0x05, 0x06, 0x06, 0x07, 0x08, 0x08, 0x09, 0x0a, 0x0b,
    0x0b, 0x0c, 0x0d, 0x0e, 0x0e, 0x0f, 0x10, 0x10, 0x11, 0x12, 0x13, 0x13, 0x14, 0x15, 0x16, 0x16,
    0x17, 0x18, 0x19, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1d, 0x1e, 0x1f, 0x20, 0x20, 0x21, 0x22, 0x23,
    0x24, 0x24, 0x25, 0x26, 0x27, 0x28, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2c, 0x2d, 0x2e, 0x2f, 0x30,
    0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3a, 0x3b, 0x3c, 0x3d,
    0x3e, 0x3f, 0x40, 0x41, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x48, 0x49, 0x4a, 0x4b,
    0x4c, 0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a,
    0x5b, 0x5c, 0x5d, 0x5e, 0x5e, 0x5f, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
    0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
    0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x87, 0x88, 0x89, 0x8a,
    0x8b, 0x8c, 0x8d, 0x8e, 0x8f, 0x90, 0x91, 0x92, 0x93, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b,
    0x9c, 0x9d, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad,
    0xaf, 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0,
    0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc8, 0xc9, 0xca, 0xcb, 0xcd, 0xce, 0xcf, 0xd0, 0xd2, 0xd3, 0xd4,
    0xd6, 0xd7, 0xd8, 0xd9, 0xdb, 0xdc, 0xdd, 0xde, 0xe0, 0xe1, 0xe2, 0xe4, 0xe5, 0xe6, 0xe8, 0xe9,
    0xea, 0xec, 0xed, 0xee, 0xf0, 0xf1, 0xf2, 0xf4, 0xf5, 0xf6, 0xf8, 0xf9, 0xfa, 0xfc, 0xfd, 0xff
};

static av_always_inline int wp_exp2(int16_t val)
{
    int res, neg = 0;

    if(val < 0){
        val = -val;
        neg = 1;
    }

    res = wp_exp2_table[val & 0xFF] | 0x100;
    val >>= 8;
    res = (val > 9) ? (res << (val - 9)) : (res >> (9 - val));
    return neg ? -res : res;
}

// macros for manipulating median values
#define GET_MED(n) ((median[n] >> 4) + 1)
#define DEC_MED(n) median[n] -= ((median[n] + (128>>n) - 2) / (128>>n)) * 2
#define INC_MED(n) median[n] += ((median[n] + (128>>n)) / (128>>n)) * 5

// macros for applying weight
#define UPDATE_WEIGHT_CLIP(weight, delta, samples, in) \
        if(samples && in){ \
            if((samples ^ in) < 0){ \
                weight -= delta; \
                if(weight < -1024) weight = -1024; \
            }else{ \
                weight += delta; \
                if(weight > 1024) weight = 1024; \
            } \
        }


static av_always_inline int get_tail(GetBitContext *gb, int k)
{
    int p, e, res;

    if(k<1)return 0;
    p = av_log2(k);
    e = (1 << (p + 1)) - k - 1;
    res = p ? get_bits(gb, p) : 0;
    if(res >= e){
        res = (res<<1) - e + get_bits1(gb);
    }
    return res;
}

static int wv_get_value(WavpackContext *ctx, GetBitContext *gb, int *median, int *last)
{
    int t, t2;
    int sign, base, add, ret;

    *last = 0;

    if((ctx->median[0] < 2U) && (ctx->median[3] < 2U) && !ctx->zero && !ctx->one){
        if(ctx->zeroes){
            ctx->zeroes--;
            if(ctx->zeroes)
                return 0;
        }else{
            t = get_unary_0_33(gb);
            if(t >= 2) t = get_bits(gb, t - 1) | (1 << (t-1));
            ctx->zeroes = t;
            if(ctx->zeroes){
                memset(ctx->median, 0, sizeof(ctx->median));
                return 0;
            }
        }
    }

    if(get_bits_count(gb) >= ctx->data_size){
        *last = 1;
        return 0;
    }

    if(ctx->zero){
        t = 0;
        ctx->zero = 0;
    }else{
        t = get_unary_0_33(gb);
        if(get_bits_count(gb) >= ctx->data_size){
            *last = 1;
            return 0;
        }
        if(t == 16) {
            t2 = get_unary_0_33(gb);
            if(t2 < 2) t += t2;
            else t += get_bits(gb, t2 - 1) | (1 << (t2 - 1));
        }

        if(ctx->one){
            ctx->one = t&1;
            t = (t>>1) + 1;
        }else{
            ctx->one = t&1;
            t >>= 1;
        }
        ctx->zero = !ctx->one;
    }

    if(!t){
        base = 0;
        add = GET_MED(0) - 1;
        DEC_MED(0);
    }else if(t == 1){
        base = GET_MED(0);
        add = GET_MED(1) - 1;
        INC_MED(0);
        DEC_MED(1);
    }else if(t == 2){
        base = GET_MED(0) + GET_MED(1);
        add = GET_MED(2) - 1;
        INC_MED(0);
        INC_MED(1);
        DEC_MED(2);
    }else{
        base = GET_MED(0) + GET_MED(1) + GET_MED(2) * (t - 2);
        add = GET_MED(2) - 1;
        INC_MED(0);
        INC_MED(1);
        INC_MED(2);
    }
    ret = base + get_tail(gb, add);
    sign = get_bits1(gb);
    return sign ? ~ret : ret;
}

static int wv_unpack_stereo(WavpackContext *s, GetBitContext *gb, int16_t *dst)
{
    int i, j, count = 0;
    int last, t;
    int A, B, L, L2, R, R2, bit;
    int pos = 0;
    uint32_t crc = 0xFFFFFFFF;

    s->one = s->zero = s->zeroes = 0;
    do{
        L = wv_get_value(s, gb, s->median, &last);
        if(last) break;
        R = wv_get_value(s, gb, s->median + 3, &last);
        if(last) break;
        for(i = 0; i < s->terms; i++){
            t = s->decorr[i].value;
            j = 0;
            if(t > 0){
                if(t > 8){
                    if(t & 1){
                        A = 2 * s->decorr[i].samplesA[0] - s->decorr[i].samplesA[1];
                        B = 2 * s->decorr[i].samplesB[0] - s->decorr[i].samplesB[1];
                    }else{
                        A = (3 * s->decorr[i].samplesA[0] - s->decorr[i].samplesA[1]) >> 1;
                        B = (3 * s->decorr[i].samplesB[0] - s->decorr[i].samplesB[1]) >> 1;
                    }
                    s->decorr[i].samplesA[1] = s->decorr[i].samplesA[0];
                    s->decorr[i].samplesB[1] = s->decorr[i].samplesB[0];
                    j = 0;
                }else{
                    A = s->decorr[i].samplesA[pos];
                    B = s->decorr[i].samplesB[pos];
                    j = (pos + t) & 7;
                }
                L2 = L + ((s->decorr[i].weightA * A + 512) >> 10);
                R2 = R + ((s->decorr[i].weightB * B + 512) >> 10);
                if(A && L) s->decorr[i].weightA -= ((((L ^ A) >> 30) & 2) - 1) * s->decorr[i].delta;
                if(B && R) s->decorr[i].weightB -= ((((R ^ B) >> 30) & 2) - 1) * s->decorr[i].delta;
                s->decorr[i].samplesA[j] = L = L2;
                s->decorr[i].samplesB[j] = R = R2;
            }else if(t == -1){
                L2 = L + ((s->decorr[i].weightA * s->decorr[i].samplesA[0] + 512) >> 10);
                UPDATE_WEIGHT_CLIP(s->decorr[i].weightA, s->decorr[i].delta, s->decorr[i].samplesA[0], L);
                L = L2;
                R2 = R + ((s->decorr[i].weightB * L2 + 512) >> 10);
                UPDATE_WEIGHT_CLIP(s->decorr[i].weightB, s->decorr[i].delta, L2, R);
                R = R2;
                s->decorr[i].samplesA[0] = R;
            }else{
                R2 = R + ((s->decorr[i].weightB * s->decorr[i].samplesB[0] + 512) >> 10);
                UPDATE_WEIGHT_CLIP(s->decorr[i].weightB, s->decorr[i].delta, s->decorr[i].samplesB[0], R);
                R = R2;

                if(t == -3){
                    R2 = s->decorr[i].samplesA[0];
                    s->decorr[i].samplesA[0] = R;
                }

                L2 = L + ((s->decorr[i].weightA * R2 + 512) >> 10);
                UPDATE_WEIGHT_CLIP(s->decorr[i].weightA, s->decorr[i].delta, R2, L);
                L = L2;
                s->decorr[i].samplesB[0] = L;
            }
        }
        pos = (pos + 1) & 7;
        if(s->joint)
            L += (R -= (L >> 1));