/*
 * ADPCM codecs
 * Copyright (c) 2001-2003 The ffmpeg Project
 *
 * 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
 */
#include "avcodec.h"
#include "get_bits.h"
#include "put_bits.h"
#include "bytestream.h"

/**
 * @file
 * ADPCM codecs.
 * First version by Francois Revol (revol@free.fr)
 * Fringe ADPCM codecs (e.g., DK3, DK4, Westwood)
 *   by Mike Melanson (melanson@pcisys.net)
 * CD-ROM XA ADPCM codec by BERO
 * EA ADPCM decoder by Robin Kay (komadori@myrealbox.com)
 *
 * Features and limitations:
 *
 * Reference documents:
 * http://www.pcisys.net/~melanson/codecs/simpleaudio.html
 * http://www.geocities.com/SiliconValley/8682/aud3.txt
 * http://openquicktime.sourceforge.net/plugins.htm
 * XAnim sources (xa_codec.c) http://www.rasnaimaging.com/people/lapus/download.html
 * http://www.cs.ucla.edu/~leec/mediabench/applications.html
 * SoX source code http://home.sprynet.com/~cbagwell/sox.html
 *
 * CD-ROM XA:
 * http://ku-www.ss.titech.ac.jp/~yatsushi/xaadpcm.html
 * vagpack & depack http://homepages.compuserve.de/bITmASTER32/psx-index.html
 * readstr http://www.geocities.co.jp/Playtown/2004/
 */

#define BLKSIZE 1024

/* step_table[] and index_table[] are from the ADPCM reference source */
/* This is the index table: */
static const int index_table[16] = {
    -1, -1, -1, -1, 2, 4, 6, 8,
    -1, -1, -1, -1, 2, 4, 6, 8,
};

/**
 * This is the step table. Note that many programs use slight deviations from
 * this table, but such deviations are negligible:
 */
static const int step_table[89] = {
    7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
    19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
    50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
    130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
    337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
    876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
    2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
    5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
    15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
};

/* These are for MS-ADPCM */
/* AdaptationTable[], AdaptCoeff1[], and AdaptCoeff2[] are from libsndfile */
static const int AdaptationTable[] = {
        230, 230, 230, 230, 307, 409, 512, 614,
        768, 614, 512, 409, 307, 230, 230, 230
};

/** Divided by 4 to fit in 8-bit integers */
static const uint8_t AdaptCoeff1[] = {
        64, 128, 0, 48, 60, 115, 98
};

/** Divided by 4 to fit in 8-bit integers */
static const int8_t AdaptCoeff2[] = {
        0, -64, 0, 16, 0, -52, -58
};

/* These are for CD-ROM XA ADPCM */
static const int xa_adpcm_table[5][2] = {
   {   0,   0 },
   {  60,   0 },
   { 115, -52 },
   {  98, -55 },
   { 122, -60 }
};

static const int ea_adpcm_table[] = {
    0, 240, 460, 392, 0, 0, -208, -220, 0, 1,
    3, 4, 7, 8, 10, 11, 0, -1, -3, -4
};

// padded to zero where table size is less then 16
static const int swf_index_tables[4][16] = {
    /*2*/ { -1, 2 },
    /*3*/ { -1, -1, 2, 4 },
    /*4*/ { -1, -1, -1, -1, 2, 4, 6, 8 },
    /*5*/ { -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 4, 6, 8, 10, 13, 16 }
};

static const int yamaha_indexscale[] = {
    230, 230, 230, 230, 307, 409, 512, 614,
    230, 230, 230, 230, 307, 409, 512, 614
};

static const int yamaha_difflookup[] = {
    1, 3, 5, 7, 9, 11, 13, 15,
    -1, -3, -5, -7, -9, -11, -13, -15
};

/* end of tables */

typedef struct ADPCMChannelStatus {
    int predictor;
    short int step_index;
    int step;
    /* for encoding */
    int prev_sample;

    /* MS version */
    short sample1;
    short sample2;
    int coeff1;
    int coeff2;
    int idelta;
} ADPCMChannelStatus;

typedef struct TrellisPath {
    int nibble;
    int prev;
} TrellisPath;

typedef struct TrellisNode {
    uint32_t ssd;
    int path;
    int sample1;
    int sample2;
    int step;
} TrellisNode;

typedef struct ADPCMContext {
    ADPCMChannelStatus status[6];
    TrellisPath *paths;
    TrellisNode *node_buf;
    TrellisNode **nodep_buf;
} ADPCMContext;

static av_cold int adpcm_decode_init(AVCodecContext * avctx)
{
    ADPCMContext *c = avctx->priv_data;
    unsigned int max_channels = 2;

    if(avctx->channels > max_channels){
        return -1;
    }

    switch(avctx->codec->id) {
    case CODEC_ID_ADPCM_CT:
        c->status[0].step = c->status[1].step = 511;
        break;
    case CODEC_ID_ADPCM_IMA_WS:
        if (avctx->extradata && avctx->extradata_size == 2 * 4) {
            c->status[0].predictor = AV_RL32(avctx->extradata);
            c->status[1].predictor = AV_RL32(avctx->extradata + 4);
        }
        break;
    default:
        break;
    }
    avctx->sample_fmt = SAMPLE_FMT_S16;
    return 0;
}

static inline short adpcm_ima_expand_nibble(ADPCMChannelStatus *c, char nibble, int shift)
{
    int step_index;
    int predictor;
    int sign, delta, diff, step;

    step = step_table[c->step_index];
    step_index = c->step_index + index_table[(unsigned)nibble];
    if (step_index < 0) step_index = 0;
    else if (step_index > 88) step_index = 88;

    sign = nibble & 8;
    delta = nibble & 7;
    /* perform direct multiplication instead of series of jumps proposed by
     * the reference ADPCM implementation since modern CPUs can do the mults
     * quickly enough */
    diff = ((2 * delta + 1) * step) >> shift;
    predictor = c->predictor;
    if (sign) predictor -= diff;
    else predictor += diff;

    c->predictor = av_clip_int16(predictor);
    c->step_index = step_index;

    return (short)c->predictor;
}

static inline short adpcm_ms_expand_nibble(ADPCMChannelStatus *c, char nibble)
{
    int predictor;

    predictor = (((c->sample1) * (c->coeff1)) + ((c->sample2) * (c->coeff2))) / 64;
    predictor += (signed)((nibble & 0x08)?(nibble - 0x10):(nibble)) * c->idelta;

    c->sample2 = c->sample1;
    c->sample1 = av_clip_int16(predictor);
    c->idelta = (AdaptationTable[(int)nibble] * c->idelta) >> 8;
    if (c->idelta < 16) c->idelta = 16;

    return c->sample1;
}

static inline short adpcm_ct_expand_nibble(ADPCMChannelStatus *c, char nibble)
{
    int sign, delta, diff;
    int new_step;

    sign = nibble & 8;
    delta = nibble & 7;
    /* perform direct multiplication instead of series of jumps proposed by
     * the reference ADPCM implementation since modern CPUs can do the mults
     * quickly enough */
    diff = ((2 * delta + 1) * c->step) >> 3;
    /* predictor update is not so trivial: predictor is multiplied on 254/256 before updating */
    c->predictor = ((c->predictor * 254) >> 8) + (sign ? -diff : diff);
    c->predictor = av_clip_int16(c->predictor);
    /* calculate new step and clamp it to range 511..32767 */
    new_step = (AdaptationTable[nibble & 7] * c->step) >> 8;
    c->step = av_clip(new_step, 511, 32767);

    return (short)c->predictor;
}

static inline short adpcm_sbpro_expand_nibble(ADPCMChannelStatus *c, char nibble, int size, int shift)
{
    int sign, delta, diff;

    sign = nibble & (1<<(size-1));
    delta = nibble & ((1<<(size-1))-1);
    diff = delta << (7 + c->step + shift);

    /* clamp result */
    c->predictor = av_clip(c->predictor + (sign ? -diff : diff), -16384,16256);

    /* calculate new step */
    if (delta >= (2*size - 3) && c->step < 3)
        c->step++;
    else if (delta == 0 && c->step > 0)
        c->step--;

    return (short) c->predictor;
}

static inline short adpcm_yamaha_expand_nibble(ADPCMChannelStatus *c, unsigned char nibble)
{
    if(!c->step) {
        c->predictor = 0;
        c->step = 127;
    }

    c->predictor += (c->step * yamaha_difflookup[nibble]) / 8;
    c->predictor = av_clip_int16(c->predictor);
    c->step = (c->step * yamaha_indexscale[nibble]) >> 8;
    c->step = av_clip(c->step, 127, 24567);
    return c->predictor;
}

static void xa_decode(short *out, const unsigned char *in,
    ADPCMChannelStatus *left, ADPCMChannelStatus *right, int inc)
{
    int i, j;
    int shift,filter,f0,f1;
    int s_1,s_2;
    int d,s,t;

    for(i=0;i<4;i++) {

        shift  = 12 - (in[4+i*2] & 15);
        filter = in[4+i*2] >> 4;
        f0 = xa_adpcm_table[filter][0];
        f1 = xa_adpcm_table[filter][1];

        s_1 = left->sample1;
        s_2 = left->sample2;

        for(j=0;j<28;j++) {
            d = in[16+i+j*4];

            t = (signed char)(d<<4)>>4;
            s = ( t<<shift ) + ((s_1*f0 + s_2*f1+32)>>6);
            s_2 = s_1;
            s_1 = av_clip_int16(s);
            *out = s_1;
            out += inc;
        }

        if (inc==2) { /* stereo */
            left->sample1 = s_1;
            left->sample2 = s_2;
            s_1 = right->sample1;
            s_2 = right->sample2;
            out = out + 1 - 28*2;
        }

        shift  = 12 - (in[5+i*2] & 15);
        filter = in[5+i*2] >> 4;

        f0 = xa_adpcm_table[filter][0];
        f1 = xa_adpcm_table[filter][1];

        for(j=0;j<28;j++) {
            d = in[16+i+j*4];

            t = (signed char)d >> 4;
            s = ( t<<shift ) + ((s_1*f0 + s_2*f1+32)>>6);
            s_2 = s_1;
            s_1 = av_clip_int16(s);
            *out = s_1;
            out += inc;
        }

        if (inc==2) { /* stereo */
            right->sample1 = s_1;
            right->sample2 = s_2;
            out -= 1;
        } else {
            left->sample1 = s_1;
            left->sample2 = s_2;
        }
    }
}


/* DK3 ADPCM support macro */
#define DK3_GET_NEXT_NIBBLE() \
    if (decode_top_nibble_next) \
    { \
        nibble = last_byte >> 4; \
        decode_top_nibble_next = 0; \
    } \
    else \
    { \
        last_byte = *src++; \
        if (src >= buf + buf_size) break; \
        nibble = last_byte & 0x0F; \
        decode_top_nibble_next = 1; \
    }

static int adpcm_decode_frame(AVCodecContext *avctx,
                            void *data, int *data_size,
                            const uint8_t *buf, int buf_size)
{
    ADPCMContext *c = avctx->priv_data;
    ADPCMChannelStatus *cs;
    int n, m, channel, i;
    int block_predictor[2];
    short *samples;
    short *samples_end;
    const uint8_t *src;
    int st; /* stereo */

    /* DK3 ADPCM accounting variables */
    unsigned char last_byte = 0;
    unsigned char nibble;
    int decode_top_nibble_next = 0;
    int diff_channel;

    /* EA ADPCM state variables */
    uint32_t samples_in_chunk;
    int32_t previous_left_sample, previous_right_sample;
    int32_t current_left_sample, current_right_sample;
    int32_t next_left_sample, next_right_sample;
    int32_t coeff1l, coeff2l, coeff1r, coeff2r;
    uint8_t shift_left, shift_right;
    int count1, count2;

    if (!buf_size)
        return 0;

    //should protect all 4bit ADPCM variants
    //8 is needed for CODEC_ID_ADPCM_IMA_WAV with 2 channels
    //
    if(*data_size/4 < buf_size + 8)
        return -1;

    samples = data;
    samples_end= samples + *data_size/2;
    *data_size= 0;
    src = buf;

    st = avctx->channels == 2 ? 1 : 0;

    switch(avctx->codec->id) {
    case CODEC_ID_ADPCM_IMA_QT:
        n = buf_size - 2*avctx->channels;
        for (channel = 0; channel < avctx->channels; channel++) {
            cs = &(c->status[channel]);
            /* (pppppp) (piiiiiii) */

            /* Bits 15-7 are the _top_ 9 bits of the 16-bit initial predictor value */
            cs->predictor = (*src++) << 8;
            cs->predictor |= (*src & 0x80);
            cs->predictor &= 0xFF80;

            /* sign extension */
            if(cs->predictor & 0x8000)
                cs->predictor -= 0x10000;

            cs->predictor = av_clip_int16(cs->predictor);

            cs->step_index = (*src++) & 0x7F;

            if (cs->step_index > 88){
                av_log(avctx, AV_LOG_ERROR, "ERROR: step_index = %i\n", cs->step_index);
                cs->step_index = 88;
            }

            cs->step = step_table[cs->step_index];

            samples = (short*)data + channel;

            for(m=32; n>0 && m>0; n--, m--) { /* in QuickTime, IMA is encoded by chuncks of 34 bytes (=64 samples) */
                *samples = adpcm_ima_expand_nibble(cs, src[0] & 0x0F, 3);
                samples += avctx->channels;
                *samples = adpcm_ima_expand_nibble(cs, src[0] >> 4  , 3);
                samples += avctx->channels;
                src ++;
            }
        }
        if (st)
            samples--;
        break;
    case CODEC_ID_ADPCM_IMA_WAV:
        if (avctx->block_align != 0 && buf_size > avctx->block_align)
            buf_size = avctx->block_align;

//        samples_per_block= (block_align-4*chanels)*8 / (bits_per_sample * chanels) + 1;

        for(i=0; i<avctx->channels; i++){
            cs = &(c->status[i]);
            cs->predictor = *samples++ = (int16_t)bytestream_get_le16(&src);

            cs->step_index = *src++;
            if (cs->step_index > 88){
                av_log(avctx, AV_LOG_ERROR, "ERROR: step_index = %i\n", cs->step_index);
                cs->step_index = 88;
            }
            if (*src++) av_log(avctx, AV_LOG_ERROR, "unused byte should be null but is %d!!\n", src[-1]); /* unused */
        }

        while(src < buf + buf_size){
            for(m=0; m<4; m++){
                for(i=0; i<=st; i++)
                    *samples++ = adpcm_ima_expand_nibble(&c->status[i], src[4*i] & 0x0F, 3);
                for(i=0; i<=st; i++)
                    *samples++ = adpcm_ima_expand_nibble(&c->status[i], src[4*i] >> 4  , 3);
                src++;
            }
            src += 4*st;
        }
        break;
    case CODEC_ID_ADPCM_4XM:
        cs = &(c->status[0]);
        c->status[0].predictor= (int16_t)bytestream_get_le16(&src);
        if(st){
            c->status[1].predictor= (int16_t)bytestream_get_le16(&src);
        }
        c->status[0].step_index= (int16_t)bytestream_get_le16(&src);
        if(st){
            c->status[1].step_index= (int16_t)bytestream_get_le16(&src);
        }
        if (cs->step_index < 0) cs->step_index = 0;
        if (cs->step_index > 88) cs->step_index = 88;

        m= (buf_size - (src - buf))>>st;
        for(i=0; i<m; i++) {
            *samples++ = adpcm_ima_expand_nibble(&c->status[0], src[i] & 0x0F, 4);
            if (st)
                *samples++ = adpcm_ima_expand_nibble(&c->status[1], src[i+m] & 0x0F, 4);
            *samples++ = adpcm_ima_expand_nibble(&c->status[0], src[i] >> 4, 4);
            if (st)
                *samples++ = adpcm_ima_expand_nibble(&c->status[1], src[i+m] >> 4, 4);
        }

        src += m<<st;

        break;
    case CODEC_ID_ADPCM_MS:
        if (avctx->block_align != 0 && buf_size > avctx->block_align)
            buf_size = avctx->block_align;
        n = buf_size - 7 * avctx->channels;
        if (n < 0)
            return -1;
        block_predictor[0] = av_clip(*src++, 0, 6);
        block_predictor[1] = 0;
        if (st)
            block_predictor[1] = av_clip(*src++, 0, 6);
        c->status[0].idelta = (int16_t)bytestream_get_le16(&src);
        if (st){
            c->status[1].idelta = (int16_t)bytestream_get_le16(&src);
        }
        c->status[0].coeff1 = AdaptCoeff1[block_predictor[0]];
        c->status[0].coeff2 = AdaptCoeff2[block_predictor[0]];
        c->status[1].coeff1 = AdaptCoeff1[block_predictor[1]];
        c->status[1].coeff2 = AdaptCoeff2[block_predictor[1]];

        c->status[0].sample1 = bytestream_get_le16(&src);
        if (st) c->status[1].sample1 = bytestream_get_le16(&src);
        c->status[0].sample2 = bytestream_get_le16(&src);
        if (st) c->status[1].sample2 = bytestream_get_le16(&src);

        *samples++ = c->status[0].sample2;
        if (st) *samples++ = c->status[1].sample2;
        *samples++ = c->status[0].sample1;
        if (st) *samples++ = c->status[1].sample1;
        for(;n>0;n--) {
            *samples++ = adpcm_ms_expand_nibble(&c->status[0 ], src[0] >> 4  );
            *samples++ = adpcm_ms_expand_nibble(&c->status[st], src[0] & 0x0F);
            src ++;
        }
        break;
    case CODEC_ID_ADPCM_IMA_DK4:
        if (avctx->block_align != 0 && buf_size > avctx->block_align)
            buf_size = avctx->block_align;

        c->status[0].predictor  = (int16_t)bytestream_get_le16(&src);
        c->status[0].step_index = *src++;
        src++;
        *samples++ = c->status[0].predictor;
        if (st) {
            c->status[1].predictor  = (int16_t)bytestream_get_le16(&src);
            c->status[1].step_index = *src++;
            src++;
            *samples++ = c->status[1].predictor;
        }
        while (src < buf + buf_size) {

            /* take care of the top nibble (always left or mono channel) */
            *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                src[0] >> 4, 3);

            /* take care of the bottom nibble, which is right sample for
             * stereo, or another mono sample */
            if (st)
                *samples++ = adpcm_ima_expand_nibble(&c->status[1],
                    src[0] & 0x0F, 3);
            else
                *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                    src[0] & 0x0F, 3);

            src++;
        }
        break;
    case CODEC_ID_ADPCM_IMA_DK3:
        if (avctx->block_align != 0 && buf_size > avctx->block_align)
            buf_size = avctx->block_align;

        if(buf_size + 16 > (samples_end - samples)*3/8)
            return -1;

        c->status[0].predictor  = (int16_t)AV_RL16(src + 10);
        c->status[1].predictor  = (int16_t)AV_RL16(src + 12);
        c->status[0].step_index = src[14];
        c->status[1].step_index = src[15];
        /* sign extend the predictors */
        src += 16;
        diff_channel = c->status[1].predictor;

        /* the DK3_GET_NEXT_NIBBLE macro issues the break statement when
         * the buffer is consumed */
        while (1) {

            /* for this algorithm, c->status[0] is the sum channel and
             * c->status[1] is the diff channel */

            /* process the first predictor of the sum channel */
            DK3_GET_NEXT_NIBBLE();
            adpcm_ima_expand_nibble(&c->status[0], nibble, 3);

            /* process the diff channel predictor */
            DK3_GET_NEXT_NIBBLE();
            adpcm_ima_expand_nibble(&c->status[1], nibble, 3);

            /* process the first pair of stereo PCM samples */
            diff_channel = (diff_channel + c->status[1].predictor) / 2;
            *samples++ = c->status[0].predictor + c->status[1].predictor;
            *samples++ = c->status[0].predictor - c->status[1].predictor;

            /* process the second predictor of the sum channel */
            DK3_GET_NEXT_NIBBLE();
            adpcm_ima_expand_nibble(&c->status[0], nibble, 3);

            /* process the second pair of stereo PCM samples */
            diff_channel = (diff_channel + c->status[1].predictor) / 2;
            *samples++ = c->status[0].predictor + c->status[1].predictor;
            *samples++ = c->status[0].predictor - c->status[1].predictor;
        }
        break;
    case CODEC_ID_ADPCM_IMA_WS:
        /* no per-block initialization; just start decoding the data */
        while (src < buf + buf_size) {

            if (st) {
                *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                    src[0] >> 4  , 3);
                *samples++ = adpcm_ima_expand_nibble(&c->status[1],
                    src[0] & 0x0F, 3);
            } else {
                *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                    src[0] >> 4  , 3);
                *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                    src[0] & 0x0F, 3);
            }

            src++;
        }
        break;
    case CODEC_ID_ADPCM_XA:
        while (buf_size >= 128) {
            xa_decode(samples, src, &c->status[0], &c->status[1],
                avctx->channels);
            src += 128;
            samples += 28 * 8;
            buf_size -= 128;
        }
        break;
    case CODEC_ID_ADPCM_EA:
        if (buf_size < 4 || AV_RL32(src) >= ((buf_size - 12) * 2)) {
            src += buf_size;
            break;
        }
        samples_in_chunk = AV_RL32(src);
        src += 4;
        current_left_sample   = (int16_t)bytestream_get_le16(&src);
        previous_left_sample  = (int16_t)bytestream_get_le16(&src);
        current_right_sample  = (int16_t)bytestream_get_le16(&src);
        previous_right_sample = (int16_t)bytestream_get_le16(&src);

        for (count1 = 0; count1 < samples_in_chunk/28;count1++) {
            coeff1l = ea_adpcm_table[ *src >> 4       ];
            coeff2l = ea_adpcm_table[(*src >> 4  ) + 4];
            coeff1r = ea_adpcm_table[*src & 0x0F];
            coeff2r = ea_adpcm_table[(*src & 0x0F) + 4];
            src++;

            shift_left  = (*src >> 4  ) + 8;
            shift_right = (*src & 0x0F) + 8;
            src++;

            for (count2 = 0; count2 < 28; count2++) {
                next_left_sample  = (int32_t)((*src & 0xF0) << 24) >> shift_left;
                next_right_sample = (int32_t)((*src & 0x0F) << 28) >> shift_right;
                src++;

                next_left_sample = (next_left_sample +
                    (current_left_sample * coeff1l) +
                    (previous_left_sample * coeff2l) + 0x80) >> 8;
                next_right_sample = (next_right_sample +
                    (current_right_sample * coeff1r) +
                    (previous_right_sample * coeff2r) + 0x80) >> 8;

                previous_left_sample = current_left_sample;
                current_left_sample = av_clip_int16(next_left_sample);
                previous_right_sample = current_right_sample;
                current_right_sample = av_clip_int16(next_right_sample);
                *samples++ = (unsigned short)current_left_sample;
                *samples++ = (unsigned short)current_right_sample;
            }
        }

        if (src - buf == buf_size - 2)
            src += 2; // Skip terminating 0x0000

        break;
    case CODEC_ID_ADPCM_IMA_AMV:
    case CODEC_ID_ADPCM_IMA_SMJPEG:
        c->status[0].predictor = (int16_t)bytestream_get_le16(&src);
        c->status[0].step_index = bytestream_get_le16(&src);

        if (avctx->codec->id == CODEC_ID_ADPCM_IMA_AMV)
            src+=4;

        while (src < buf + buf_size) {
            char hi, lo;
            lo = *src & 0x0F;
            hi = *src >> 4;

            if (avctx->codec->id == CODEC_ID_ADPCM_IMA_AMV)
                FFSWAP(char, hi, lo);

            *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                lo, 3);
            *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                hi, 3);
            src++;
        }
        break;
    case CODEC_ID_ADPCM_CT:
        while (src < buf + buf_size) {
            if (st) {
                *samples++ = adpcm_ct_expand_nibble(&c->status[0],
                    src[0] >> 4);
                *samples++ = adpcm_ct_expand_nibble(&c->status[1],
                    src[0] & 0x0F);
            } else {
                *samples++ = adpcm_ct_expand_nibble(&c->status[0],
                    src[0] >> 4);
                *samples++ = adpcm_ct_expand_nibble(&c->status[0],
                    src[0] & 0x0F);
            }
            src++;
        }
        break;
    case CODEC_ID_ADPCM_SBPRO_4:
    case CODEC_ID_ADPCM_SBPRO_3:
    case CODEC_ID_ADPCM_SBPRO_2:
        if (!c->status[0].step_index) {
            /* the first byte is a raw sample */
            *samples++ = 128 * (*src++ - 0x80);
            if (st)
              *samples++ = 128 * (*src++ - 0x80);
            c->status[0].step_index = 1;
        }
        if (avctx->codec->id == CODEC_ID_ADPCM_SBPRO_4) {
            while (src < buf + buf_size) {
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[0],
                    src[0] >> 4, 4, 0);
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[st],
                    src[0] & 0x0F, 4, 0);
                src++;
            }
        } else if (avctx->codec->id == CODEC_ID_ADPCM_SBPRO_3) {
            while (src < buf + buf_size && samples + 2 < samples_end) {
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[0],
                     src[0] >> 5        , 3, 0);
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[0],
                    (src[0] >> 2) & 0x07, 3, 0);
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[0],
                    src[0] & 0x03, 2, 0);
                src++;
            }
        } else {
            while (src < buf + buf_size && samples + 3 < samples_end) {
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[0],
                     src[0] >> 6        , 2, 2);
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[st],
                    (src[0] >> 4) & 0x03, 2, 2);
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[0],
                    (src[0] >> 2) & 0x03, 2, 2);
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[st],
                    src[0] & 0x03, 2, 2);
                src++;
            }
        }
        break;
    case CODEC_ID_ADPCM_SWF:
    {
        GetBitContext gb;
        const int *table;
        int k0, signmask, nb_bits, count;
        int size = buf_size*8;

        init_get_bits(&gb, buf, size);

        //read bits & initial values
        nb_bits = get_bits(&gb, 2)+2;
        //av_log(NULL,AV_LOG_INFO,"nb_bits: %d\n", nb_bits);
        table = swf_index_tables[nb_bits-2];
        k0 = 1 << (nb_bits-2);
        signmask = 1 << (nb_bits-1);

        while (get_bits_count(&gb) <= size - 22*avctx->channels) {
            for (i = 0; i < avctx->channels; i++) {
                *samples++ = c->status[i].predictor = get_sbits(&gb, 16);
                c->status[i].step_index = get_bits(&gb, 6);
            }

            for (count = 0; get_bits_count(&gb) <= size - nb_bits*avctx->channels && count < 4095; count++) {
                int i;

                for (i = 0; i < avctx->channels; i++) {
                    // similar to IMA adpcm
                    int delta = get_bits(&gb, nb_bits);
                    int step = step_table[c->status[i].step_index];
                    long vpdiff = 0; // vpdiff = (delta+0.5)*step/4
                    int k = k0;

                    do {
                        if (delta & k)
                            vpdiff += step;
                        step >>= 1;
                        k >>= 1;
                    } while(k);
                    vpdiff += step;

                    if (delta & signmask)
                        c->status[i].predictor -= vpdiff;
                    else
                        c->status[i].predictor += vpdiff;

                    c->status[i].step_index += table[delta & (~signmask)];

                    c->status[i].step_index = av_clip(c->status[i].step_index, 0, 88);
                    c->status[i].predictor = av_clip_int16(c->status[i].predictor);

                    *samples++ = c->status[i].predictor;
                    if (samples >= samples_end) {
                        av_log(avctx, AV_LOG_ERROR, "allocated output buffer is too small\n");
                        return -1;
                    }
                }
            }
        }
        src += buf_size;
        break;
    }
    case CODEC_ID_ADPCM_YAMAHA:
        while (src < buf + buf_size) {
            if (st) {
                *samples++ = adpcm_yamaha_expand_nibble(&c->status[0],
                        src[0] & 0x0F);
                *samples++ = adpcm_yamaha_expand_nibble(&c->status[1],
                        src[0] >> 4  );
            } else {
                *samples++ = adpcm_yamaha_expand_nibble(&c->status[0],
                        src[0] & 0x0F);
                *samples++ = adpcm_yamaha_expand_nibble(&c->status[0],
                        src[0] >> 4  );
            }
            src++;
        }
        break;

    default:
        return -1;
    }
    *data_size = (uint8_t *)samples - (uint8_t *)data;
    return src - buf;
}

#if CONFIG_DECODERS
#define ADPCM_DECODER(id,name,long_name_)       \
AVCodec name ## _decoder = {                    \
    #name,                                      \
    AVMEDIA_TYPE_AUDIO,                         \
    id,                                         \
    sizeof(ADPCMContext),                       \
    adpcm_decode_init,                          \
    NULL,                                       \
    NULL,                                       \
    adpcm_decode_frame,                         \
    /*.capabilities = */0,                      \
    /*.next = */NULL,                           \
    /*.flush = */NULL,                          \
    /*.supported_framerates = */NULL,           \
    /*.pix_fmts = */NULL,                       \
    /*.long_name = */NULL_IF_CONFIG_SMALL(long_name_), \
};
#else
#define ADPCM_DECODER(id,name,long_name_)
#endif

/* Note: Do not forget to add new entries to the Makefile as well. */
ADPCM_DECODER(CODEC_ID_ADPCM_4XM, adpcm_4xm, "ADPCM 4X Movie");
ADPCM_DECODER(CODEC_ID_ADPCM_CT, adpcm_ct, "ADPCM Creative Technology");
ADPCM_DECODER(CODEC_ID_ADPCM_EA, adpcm_ea, "ADPCM Electronic Arts");
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_AMV, adpcm_ima_amv, "ADPCM IMA AMV");
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_DK3, adpcm_ima_dk3, "ADPCM IMA Duck DK3");
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_DK4, adpcm_ima_dk4, "ADPCM IMA Duck DK4");
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_QT, adpcm_ima_qt, "ADPCM IMA QuickTime");
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_SMJPEG, adpcm_ima_smjpeg, "ADPCM IMA Loki SDL MJPEG");
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_WAV, adpcm_ima_wav, "ADPCM IMA WAV");
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_WS, adpcm_ima_ws, "ADPCM IMA Westwood");
ADPCM_DECODER(CODEC_ID_ADPCM_MS, adpcm_ms, "ADPCM Microsoft");
ADPCM_DECODER(CODEC_ID_ADPCM_SBPRO_2, adpcm_sbpro_2, "ADPCM Sound Blaster Pro 2-bit");
ADPCM_DECODER(CODEC_ID_ADPCM_SBPRO_3, adpcm_sbpro_3, "ADPCM Sound Blaster Pro 2.6-bit");
ADPCM_DECODER(CODEC_ID_ADPCM_SBPRO_4, adpcm_sbpro_4, "ADPCM Sound Blaster Pro 4-bit");
ADPCM_DECODER(CODEC_ID_ADPCM_SWF, adpcm_swf, "ADPCM Shockwave Flash");
ADPCM_DECODER(CODEC_ID_ADPCM_XA, adpcm_xa, "ADPCM CDROM XA");
ADPCM_DECODER(CODEC_ID_ADPCM_YAMAHA, adpcm_yamaha, "ADPCM Yamaha");