PeerStreamer

/*

 * IMC compatible decoder

 * Copyright (c) 2002-2004 Maxim Poliakovski

 * Copyright (c) 2006 Benjamin Larsson

 * 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

 */

/**

 *  @file

 *  IMC - Intel Music Coder

 *  A mdct based codec using a 256 points large transform

 *  divied into 32 bands with some mix of scale factors.

 *  Only mono is supported.

 *

 */

#include <math.h>

#include <stddef.h>

#include <stdio.h>

#define ALT_BITSTREAM_READER

#include "avcodec.h"

#include "get_bits.h"

#include "dsputil.h"

#include "fft.h"

#include "libavcore/audioconvert.h"

#include "imcdata.h"

#define IMC_BLOCK_SIZE 64

#define IMC_FRAME_ID 0x21

#define BANDS 32

#define COEFFS 256

typedef struct {

    float old_floor[BANDS];

    float flcoeffs1[BANDS];

    float flcoeffs2[BANDS];

    float flcoeffs3[BANDS];

    float flcoeffs4[BANDS];

    float flcoeffs5[BANDS];

    float flcoeffs6[BANDS];

    float CWdecoded[COEFFS];

    /** MDCT tables */

    //@{

    float mdct_sine_window[COEFFS];

    float post_cos[COEFFS];

    float post_sin[COEFFS];

    float pre_coef1[COEFFS];

    float pre_coef2[COEFFS];

    float last_fft_im[COEFFS];

    //@}

    int bandWidthT[BANDS];     ///< codewords per band

    int bitsBandT[BANDS];      ///< how many bits per codeword in band

    int CWlengthT[COEFFS];     ///< how many bits in each codeword

    int levlCoeffBuf[BANDS];

    int bandFlagsBuf[BANDS];   ///< flags for each band

    int sumLenArr[BANDS];      ///< bits for all coeffs in band

    int skipFlagRaw[BANDS];    ///< skip flags are stored in raw form or not

    int skipFlagBits[BANDS];   ///< bits used to code skip flags

    int skipFlagCount[BANDS];  ///< skipped coeffients per band

    int skipFlags[COEFFS];     ///< skip coefficient decoding or not

    int codewords[COEFFS];     ///< raw codewords read from bitstream

    float sqrt_tab[30];

    GetBitContext gb;

    int decoder_reset;

    float one_div_log2;

    DSPContext dsp;

    FFTContext fft;

    DECLARE_ALIGNED(16, FFTComplex, samples)[COEFFS/2];

    float *out_samples;

} IMCContext;

static VLC huffman_vlc[4][4];

#define VLC_TABLES_SIZE 9512

static const int vlc_offsets[17] = {

    0,     640, 1156, 1732, 2308, 2852, 3396, 3924,

    4452, 5220, 5860, 6628, 7268, 7908, 8424, 8936, VLC_TABLES_SIZE};

static VLC_TYPE vlc_tables[VLC_TABLES_SIZE][2];

static av_cold int imc_decode_init(AVCodecContext * avctx)

{

    int i, j;

    IMCContext *q = avctx->priv_data;

    double r1, r2;

    q->decoder_reset = 1;

    for(i = 0; i < BANDS; i++)

        q->old_floor[i] = 1.0;

    /* Build mdct window, a simple sine window normalized with sqrt(2) */

    ff_sine_window_init(q->mdct_sine_window, COEFFS);

    for(i = 0; i < COEFFS; i++)

        q->mdct_sine_window[i] *= sqrt(2.0);

    for(i = 0; i < COEFFS/2; i++){

        q->post_cos[i] = (1.0f / 32768) * cos(i / 256.0 * M_PI);

        q->post_sin[i] = (1.0f / 32768) * sin(i / 256.0 * M_PI);

        r1 = sin((i * 4.0 + 1.0) / 1024.0 * M_PI);

        r2 = cos((i * 4.0 + 1.0) / 1024.0 * M_PI);

        if (i & 0x1)

        {

            q->pre_coef1[i] =  (r1 + r2) * sqrt(2.0);

            q->pre_coef2[i] = -(r1 - r2) * sqrt(2.0);

        }

        else

        {

            q->pre_coef1[i] = -(r1 + r2) * sqrt(2.0);

            q->pre_coef2[i] =  (r1 - r2) * sqrt(2.0);

        }

        q->last_fft_im[i] = 0;

    }

    /* Generate a square root table */

    for(i = 0; i < 30; i++) {

        q->sqrt_tab[i] = sqrt(i);

    }

    /* initialize the VLC tables */

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

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

            huffman_vlc[i][j].table = &vlc_tables[vlc_offsets[i * 4 + j]];

            huffman_vlc[i][j].table_allocated = vlc_offsets[i * 4 + j + 1] - vlc_offsets[i * 4 + j];

            init_vlc(&huffman_vlc[i][j], 9, imc_huffman_sizes[i],

                     imc_huffman_lens[i][j], 1, 1,

                     imc_huffman_bits[i][j], 2, 2, INIT_VLC_USE_NEW_STATIC);

        }

    }

    q->one_div_log2 = 1/log(2);

    ff_fft_init(&q->fft, 7, 1);

    dsputil_init(&q->dsp, avctx);

    avctx->sample_fmt = AV_SAMPLE_FMT_FLT;

    avctx->channel_layout = (avctx->channels==2) ? AV_CH_LAYOUT_STEREO : AV_CH_LAYOUT_MONO;

    return 0;

}

static void imc_calculate_coeffs(IMCContext* q, float* flcoeffs1, float* flcoeffs2, int* bandWidthT,

                                float* flcoeffs3, float* flcoeffs5)

{

    float   workT1[BANDS];

    float   workT2[BANDS];

    float   workT3[BANDS];

    float   snr_limit = 1.e-30;

    float   accum = 0.0;

    int i, cnt2;

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

        flcoeffs5[i] = workT2[i] = 0.0;

        if (bandWidthT[i]){

            workT1[i] = flcoeffs1[i] * flcoeffs1[i];

            flcoeffs3[i] = 2.0 * flcoeffs2[i];

        } else {

            workT1[i] = 0.0;

            flcoeffs3[i] = -30000.0;

        }

        workT3[i] = bandWidthT[i] * workT1[i] * 0.01;

        if (workT3[i] <= snr_limit)

            workT3[i] = 0.0;

    }

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

        for(cnt2 = i; cnt2 < cyclTab[i]; cnt2++)

            flcoeffs5[cnt2] = flcoeffs5[cnt2] + workT3[i];

        workT2[cnt2-1] = workT2[cnt2-1] + workT3[i];

    }

    for(i = 1; i < BANDS; i++) {

        accum = (workT2[i-1] + accum) * imc_weights1[i-1];

        flcoeffs5[i] += accum;

    }

    for(i = 0; i < BANDS; i++)

        workT2[i] = 0.0;

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

        for(cnt2 = i-1; cnt2 > cyclTab2[i]; cnt2--)

            flcoeffs5[cnt2] += workT3[i];

        workT2[cnt2+1] += workT3[i];

    }

    accum = 0.0;

    for(i = BANDS-2; i >= 0; i--) {

        accum = (workT2[i+1] + accum) * imc_weights2[i];

        flcoeffs5[i] += accum;

        //there is missing code here, but it seems to never be triggered

    }

}

static void imc_read_level_coeffs(IMCContext* q, int stream_format_code, int* levlCoeffs)

{

    int i;

    VLC *hufftab[4];

    int start = 0;

    const uint8_t *cb_sel;

    int s;

    s = stream_format_code >> 1;

    hufftab[0] = &huffman_vlc[s][0];

    hufftab[1] = &huffman_vlc[s][1];

    hufftab[2] = &huffman_vlc[s][2];

    hufftab[3] = &huffman_vlc[s][3];

    cb_sel = imc_cb_select[s];

    if(stream_format_code & 4)

        start = 1;

    if(start)

        levlCoeffs[0] = get_bits(&q->gb, 7);

    for(i = start; i < BANDS; i++){

        levlCoeffs[i] = get_vlc2(&q->gb, hufftab[cb_sel[i]]->table, hufftab[cb_sel[i]]->bits, 2);

        if(levlCoeffs[i] == 17)

            levlCoeffs[i] += get_bits(&q->gb, 4);

    }

}

static void imc_decode_level_coefficients(IMCContext* q, int* levlCoeffBuf, float* flcoeffs1,

                                         float* flcoeffs2)

{

    int i, level;

    float tmp, tmp2;

    //maybe some frequency division thingy

    flcoeffs1[0] = 20000.0 / pow (2, levlCoeffBuf[0] * 0.18945); // 0.18945 = log2(10) * 0.05703125

    flcoeffs2[0] = log(flcoeffs1[0])/log(2);

    tmp = flcoeffs1[0];

    tmp2 = flcoeffs2[0];

    for(i = 1; i < BANDS; i++) {

        level = levlCoeffBuf[i];

        if (level == 16) {

            flcoeffs1[i] = 1.0;

            flcoeffs2[i] = 0.0;

        } else {

            if (level < 17)

                level -=7;

            else if (level <= 24)

                level -=32;

            else

                level -=16;

            tmp  *= imc_exp_tab[15 + level];

            tmp2 += 0.83048 * level;  // 0.83048 = log2(10) * 0.25

            flcoeffs1[i] = tmp;

            flcoeffs2[i] = tmp2;

        }

    }

}

static void imc_decode_level_coefficients2(IMCContext* q, int* levlCoeffBuf, float* old_floor, float* flcoeffs1,

                                          float* flcoeffs2) {

    int i;

        //FIXME maybe flag_buf = noise coding and flcoeffs1 = new scale factors

        //      and flcoeffs2 old scale factors

        //      might be incomplete due to a missing table that is in the binary code

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

        flcoeffs1[i] = 0;

        if(levlCoeffBuf[i] < 16) {

            flcoeffs1[i] = imc_exp_tab2[levlCoeffBuf[i]] * old_floor[i];

            flcoeffs2[i] = (levlCoeffBuf[i]-7) * 0.83048 + flcoeffs2[i]; // 0.83048 = log2(10) * 0.25

        } else {

            flcoeffs1[i] = old_floor[i];

        }

    }

}

/**

 * Perform bit allocation depending on bits available

 */

static int bit_allocation (IMCContext* q, int stream_format_code, int freebits, int flag) {

    int i, j;

    const float limit = -1.e20;

    float highest = 0.0;

    int indx;

    int t1 = 0;

    int t2 = 1;

    float summa = 0.0;

    int iacc = 0;

    int summer = 0;

    int rres, cwlen;

    float lowest = 1.e10;

    int low_indx = 0;

    float workT[32];

    int flg;

    int found_indx = 0;

    for(i = 0; i < BANDS; i++)

        highest = FFMAX(highest, q->flcoeffs1[i]);

    for(i = 0; i < BANDS-1; i++) {

        q->flcoeffs4[i] = q->flcoeffs3[i] - log(q->flcoeffs5[i])/log(2);

    }

    q->flcoeffs4[BANDS - 1] = limit;

    highest = highest * 0.25;

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

        indx = -1;

        if ((band_tab[i+1] - band_tab[i]) == q->bandWidthT[i])

            indx = 0;

        if ((band_tab[i+1] - band_tab[i]) > q->bandWidthT[i])

            indx = 1;

        if (((band_tab[i+1] - band_tab[i])/2) >= q->bandWidthT[i])

            indx = 2;

        if (indx == -1)

            return -1;

        q->flcoeffs4[i] = q->flcoeffs4[i] + xTab[(indx*2 + (q->flcoeffs1[i] < highest)) * 2 + flag];

    }

    if (stream_format_code & 0x2) {

        q->flcoeffs4[0] = limit;

        q->flcoeffs4[1] = limit;

        q->flcoeffs4[2] = limit;

        q->flcoeffs4[3] = limit;

    }

    for(i = (stream_format_code & 0x2)?4:0; i < BANDS-1; i++) {

        iacc += q->bandWidthT[i];

        summa += q->bandWidthT[i] * q->flcoeffs4[i];

    }

    q->bandWidthT[BANDS-1] = 0;

    summa = (summa * 0.5 - freebits) / iacc;

    for(i = 0; i < BANDS/2; i++) {

        rres = summer - freebits;

        if((rres >= -8) && (rres <= 8)) break;

        summer = 0;

        iacc = 0;

        for(j = (stream_format_code & 0x2)?4:0; j < BANDS; j++) {

            cwlen = av_clipf(((q->flcoeffs4[j] * 0.5) - summa + 0.5), 0, 6);

            q->bitsBandT[j] = cwlen;

            summer += q->bandWidthT[j] * cwlen;

            if (cwlen > 0)

                iacc += q->bandWidthT[j];

        }

        flg = t2;

        t2 = 1;

        if (freebits < summer)

            t2 = -1;

        if (i == 0)

            flg = t2;

        if(flg != t2)

            t1++;

        summa = (float)(summer - freebits) / ((t1 + 1) * iacc) + summa;

    }

    for(i = (stream_format_code & 0x2)?4:0; i < BANDS; i++) {

        for(j = band_tab[i]; j < band_tab[i+1]; j++)

            q->CWlengthT[j] = q->bitsBandT[i];

    }

    if (freebits > summer) {

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

            workT[i] = (q->bitsBandT[i] == 6) ? -1.e20 : (q->bitsBandT[i] * -2 + q->flcoeffs4[i] - 0.415);

        }

        highest = 0.0;

        do{

            if (highest <= -1.e20)

                break;

            found_indx = 0;

            highest = -1.e20;

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

                if (workT[i] > highest) {

                    highest = workT[i];

                    found_indx = i;

                }

            }

            if (highest > -1.e20) {

                workT[found_indx] -= 2.0;

                if (++(q->bitsBandT[found_indx]) == 6)

                    workT[found_indx] = -1.e20;

                for(j = band_tab[found_indx]; j < band_tab[found_indx+1] && (freebits > summer); j++){

                    q->CWlengthT[j]++;

                    summer++;

                }

            }

        }while (freebits > summer);

    }

    if (freebits < summer) {

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

            workT[i] = q->bitsBandT[i] ? (q->bitsBandT[i] * -2 + q->flcoeffs4[i] + 1.585) : 1.e20;

        }

        if (stream_format_code & 0x2) {

            workT[0] = 1.e20;

            workT[1] = 1.e20;

            workT[2] = 1.e20;

            workT[3] = 1.e20;

        }

        while (freebits < summer){

            lowest = 1.e10;

            low_indx = 0;

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

                if (workT[i] < lowest) {

                    lowest = workT[i];

                    low_indx = i;

                }

            }

            //if(lowest >= 1.e10) break;

            workT[low_indx] = lowest + 2.0;

            if (!(--q->bitsBandT[low_indx]))

                workT[low_indx] = 1.e20;

            for(j = band_tab[low_indx]; j < band_tab[low_indx+1] && (freebits < summer); j++){

                if(q->CWlengthT[j] > 0){

                    q->CWlengthT[j]--;

                    summer--;

                }

            }

        }

    }

    return 0;

}

static void imc_get_skip_coeff(IMCContext* q) {

    int i, j;

    memset(q->skipFlagBits, 0, sizeof(q->skipFlagBits));

    memset(q->skipFlagCount, 0, sizeof(q->skipFlagCount));

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

        if (!q->bandFlagsBuf[i] || !q->bandWidthT[i])

            continue;

        if (!q->skipFlagRaw[i]) {

            q->skipFlagBits[i] = band_tab[i+1] - band_tab[i];

            for(j = band_tab[i]; j < band_tab[i+1]; j++) {

                if ((q->skipFlags[j] = get_bits1(&q->gb)))

                    q->skipFlagCount[i]++;

            }

        } else {

            for(j = band_tab[i]; j < (band_tab[i+1]-1); j += 2) {

                if(!get_bits1(&q->gb)){//0

                    q->skipFlagBits[i]++;

                    q->skipFlags[j]=1;

                    q->skipFlags[j+1]=1;

                    q->skipFlagCount[i] += 2;

                }else{

                    if(get_bits1(&q->gb)){//11

                        q->skipFlagBits[i] +=2;

                        q->skipFlags[j]=0;

                        q->skipFlags[j+1]=1;

                        q->skipFlagCount[i]++;

                    }else{

                        q->skipFlagBits[i] +=3;

                        q->skipFlags[j+1]=0;

                        if(!get_bits1(&q->gb)){//100

                            q->skipFlags[j]=1;

                            q->skipFlagCount[i]++;

                        }else{//101

                            q->skipFlags[j]=0;

                        }

                    }

                }

            }

            if (j < band_tab[i+1]) {

                q->skipFlagBits[i]++;

                if ((q->skipFlags[j] = get_bits1(&q->gb)))

                    q->skipFlagCount[i]++;

            }

        }

    }

}

/**

 * Increase highest' band coefficient sizes as some bits won't be used

 */

static void imc_adjust_bit_allocation (IMCContext* q, int summer) {

    float workT[32];

    int corrected = 0;

    int i, j;

    float highest = 0;

    int found_indx=0;

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

        workT[i] = (q->bitsBandT[i] == 6) ? -1.e20 : (q->bitsBandT[i] * -2 + q->flcoeffs4[i] - 0.415);

    }

    while (corrected < summer) {

        if(highest <= -1.e20)

            break;

        highest = -1.e20;

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

            if (workT[i] > highest) {

                highest = workT[i];

                found_indx = i;

            }

        }

        if (highest > -1.e20) {

            workT[found_indx] -= 2.0;

            if (++(q->bitsBandT[found_indx]) == 6)

                workT[found_indx] = -1.e20;

            for(j = band_tab[found_indx]; j < band_tab[found_indx+1] && (corrected < summer); j++) {

                if (!q->skipFlags[j] && (q->CWlengthT[j] < 6)) {

                    q->CWlengthT[j]++;

                    corrected++;

                }

            }

        }

    }

}

static void imc_imdct256(IMCContext *q) {

    int i;

    float re, im;

    /* prerotation */

    for(i=0; i < COEFFS/2; i++){

        q->samples[i].re = -(q->pre_coef1[i] * q->CWdecoded[COEFFS-1-i*2]) -

                           (q->pre_coef2[i] * q->CWdecoded[i*2]);

        q->samples[i].im = (q->pre_coef2[i] * q->CWdecoded[COEFFS-1-i*2]) -

                           (q->pre_coef1[i] * q->CWdecoded[i*2]);

    }

    /* FFT */

    ff_fft_permute(&q->fft, q->samples);

    ff_fft_calc (&q->fft, q->samples);

    /* postrotation, window and reorder */

    for(i = 0; i < COEFFS/2; i++){

        re = (q->samples[i].re * q->post_cos[i]) + (-q->samples[i].im * q->post_sin[i]);

        im = (-q->samples[i].im * q->post_cos[i]) - (q->samples[i].re * q->post_sin[i]);

        q->out_samples[i*2] = (q->mdct_sine_window[COEFFS-1-i*2] * q->last_fft_im[i]) + (q->mdct_sine_window[i*2] * re);

        q->out_samples[COEFFS-1-i*2] = (q->mdct_sine_window[i*2] * q->last_fft_im[i]) - (q->mdct_sine_window[COEFFS-1-i*2] * re);

        q->last_fft_im[i] = im;

    }

}

static int inverse_quant_coeff (IMCContext* q, int stream_format_code) {

    int i, j;

    int middle_value, cw_len, max_size;

    const float* quantizer;

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

        for(j = band_tab[i]; j < band_tab[i+1]; j++) {

            q->CWdecoded[j] = 0;

            cw_len = q->CWlengthT[j];

            if (cw_len <= 0 || q->skipFlags[j])

                continue;

            max_size = 1 << cw_len;

            middle_value = max_size >> 1;

            if (q->codewords[j] >= max_size || q->codewords[j] < 0)

                return -1;

            if (cw_len >= 4){

                quantizer = imc_quantizer2[(stream_format_code & 2) >> 1];

                if (q->codewords[j] >= middle_value)

                    q->CWdecoded[j] = quantizer[q->codewords[j] - 8] * q->flcoeffs6[i];

                else

                    q->CWdecoded[j] = -quantizer[max_size - q->codewords[j] - 8 - 1] * q->flcoeffs6[i];

            }else{

                quantizer = imc_quantizer1[((stream_format_code & 2) >> 1) | (q->bandFlagsBuf[i] << 1)];

                if (q->codewords[j] >= middle_value)

                    q->CWdecoded[j] = quantizer[q->codewords[j] - 1] * q->flcoeffs6[i];

                else

                    q->CWdecoded[j] = -quantizer[max_size - 2 - q->codewords[j]] * q->flcoeffs6[i];

            }

        }

    }

    return 0;

}

static int imc_get_coeffs (IMCContext* q) {

    int i, j, cw_len, cw;

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

        if(!q->sumLenArr[i]) continue;

        if (q->bandFlagsBuf[i] || q->bandWidthT[i]) {

            for(j = band_tab[i]; j < band_tab[i+1]; j++) {

                cw_len = q->CWlengthT[j];

                cw = 0;

                if (get_bits_count(&q->gb) + cw_len > 512){

//av_log(NULL,0,"Band %i coeff %i cw_len %i\n",i,j,cw_len);

                    return -1;

                }

                if(cw_len && (!q->bandFlagsBuf[i] || !q->skipFlags[j]))

                    cw = get_bits(&q->gb, cw_len);

                q->codewords[j] = cw;

            }

        }

    }

    return 0;

}

static int imc_decode_frame(AVCodecContext * avctx,

                            void *data, int *data_size,

                            AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    IMCContext *q = avctx->priv_data;

    int stream_format_code;

    int imc_hdr, i, j;

    int flag;

    int bits, summer;

    int counter, bitscount;

    uint16_t buf16[IMC_BLOCK_SIZE / 2];

    if (buf_size < IMC_BLOCK_SIZE) {

        av_log(avctx, AV_LOG_ERROR, "imc frame too small!\n");

        return -1;

    }

    for(i = 0; i < IMC_BLOCK_SIZE / 2; i++)

        buf16[i] = av_bswap16(((const uint16_t*)buf)[i]);

    q->out_samples = data;

    init_get_bits(&q->gb, (const uint8_t*)buf16, IMC_BLOCK_SIZE * 8);

    /* Check the frame header */

    imc_hdr = get_bits(&q->gb, 9);

    if (imc_hdr != IMC_FRAME_ID) {

        av_log(avctx, AV_LOG_ERROR, "imc frame header check failed!\n");

        av_log(avctx, AV_LOG_ERROR, "got %x instead of 0x21.\n", imc_hdr);

        return -1;

    }

    stream_format_code = get_bits(&q->gb, 3);

    if(stream_format_code & 1){

        av_log(avctx, AV_LOG_ERROR, "Stream code format %X is not supported\n", stream_format_code);

        return -1;

    }

//    av_log(avctx, AV_LOG_DEBUG, "stream_format_code = %d\n", stream_format_code);

    if (stream_format_code & 0x04)

        q->decoder_reset = 1;

    if(q->decoder_reset) {

        memset(q->out_samples, 0, sizeof(q->out_samples));

        for(i = 0; i < BANDS; i++)q->old_floor[i] = 1.0;

        for(i = 0; i < COEFFS; i++)q->CWdecoded[i] = 0;

        q->decoder_reset = 0;

    }

    flag = get_bits1(&q->gb);

    imc_read_level_coeffs(q, stream_format_code, q->levlCoeffBuf);

    if (stream_format_code & 0x4)

        imc_decode_level_coefficients(q, q->levlCoeffBuf, q->flcoeffs1, q->flcoeffs2);

    else

        imc_decode_level_coefficients2(q, q->levlCoeffBuf, q->old_floor, q->flcoeffs1, q->flcoeffs2);

    memcpy(q->old_floor, q->flcoeffs1, 32 * sizeof(float));

    counter = 0;

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

        if (q->levlCoeffBuf[i] == 16) {

            q->bandWidthT[i] = 0;

            counter++;

        } else

            q->bandWidthT[i] = band_tab[i+1] - band_tab[i];

    }

    memset(q->bandFlagsBuf, 0, BANDS * sizeof(int));

    for(i = 0; i < BANDS-1; i++) {

        if (q->bandWidthT[i])

            q->bandFlagsBuf[i] = get_bits1(&q->gb);

    }

    imc_calculate_coeffs(q, q->flcoeffs1, q->flcoeffs2, q->bandWidthT, q->flcoeffs3, q->flcoeffs5);

    bitscount = 0;

    /* first 4 bands will be assigned 5 bits per coefficient */

    if (stream_format_code & 0x2) {

        bitscount += 15;

        q->bitsBandT[0] = 5;

        q->CWlengthT[0] = 5;

        q->CWlengthT[1] = 5;

        q->CWlengthT[2] = 5;

        for(i = 1; i < 4; i++){

            bits = (q->levlCoeffBuf[i] == 16) ? 0 : 5;

            q->bitsBandT[i] = bits;

            for(j = band_tab[i]; j < band_tab[i+1]; j++) {

                q->CWlengthT[j] = bits;

                bitscount += bits;

            }

        }

    }

    if(bit_allocation (q, stream_format_code, 512 - bitscount - get_bits_count(&q->gb), flag) < 0) {

        av_log(avctx, AV_LOG_ERROR, "Bit allocations failed\n");

        q->decoder_reset = 1;

        return -1;

    }

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

        q->sumLenArr[i] = 0;

        q->skipFlagRaw[i] = 0;

        for(j = band_tab[i]; j < band_tab[i+1]; j++)

            q->sumLenArr[i] += q->CWlengthT[j];

        if (q->bandFlagsBuf[i])

            if( (((band_tab[i+1] - band_tab[i]) * 1.5) > q->sumLenArr[i]) && (q->sumLenArr[i] > 0))

                q->skipFlagRaw[i] = 1;

    }

    imc_get_skip_coeff(q);

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

        q->flcoeffs6[i] = q->flcoeffs1[i];

        /* band has flag set and at least one coded coefficient */

        if (q->bandFlagsBuf[i] && (band_tab[i+1] - band_tab[i]) != q->skipFlagCount[i]){

                q->flcoeffs6[i] *= q->sqrt_tab[band_tab[i+1] - band_tab[i]] /

                                   q->sqrt_tab[(band_tab[i+1] - band_tab[i] - q->skipFlagCount[i])];

        }

    }

    /* calculate bits left, bits needed and adjust bit allocation */

    bits = summer = 0;

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

        if (q->bandFlagsBuf[i]) {

            for(j = band_tab[i]; j < band_tab[i+1]; j++) {

                if(q->skipFlags[j]) {

                    summer += q->CWlengthT[j];

                    q->CWlengthT[j] = 0;

                }

            }

            bits += q->skipFlagBits[i];

            summer -= q->skipFlagBits[i];

        }

    }

    imc_adjust_bit_allocation(q, summer);

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

        q->sumLenArr[i] = 0;

        for(j = band_tab[i]; j < band_tab[i+1]; j++)

            if (!q->skipFlags[j])

                q->sumLenArr[i] += q->CWlengthT[j];

    }

    memset(q->codewords, 0, sizeof(q->codewords));

    if(imc_get_coeffs(q) < 0) {

        av_log(avctx, AV_LOG_ERROR, "Read coefficients failed\n");

        q->decoder_reset = 1;

        return 0;

    }

    if(inverse_quant_coeff(q, stream_format_code) < 0) {

        av_log(avctx, AV_LOG_ERROR, "Inverse quantization of coefficients failed\n");

        q->decoder_reset = 1;

        return 0;

    }

    memset(q->skipFlags, 0, sizeof(q->skipFlags));

    imc_imdct256(q);

    *data_size = COEFFS * sizeof(float);

    return IMC_BLOCK_SIZE;

}

static av_cold int imc_decode_close(AVCodecContext * avctx)

{

    IMCContext *q = avctx->priv_data;

    ff_fft_end(&q->fft);

    return 0;

}

AVCodec ff_imc_decoder = {

    .name = "imc",

    .type = AVMEDIA_TYPE_AUDIO,

    .id = CODEC_ID_IMC,

    .priv_data_size = sizeof(IMCContext),

    .init = imc_decode_init,

    .close = imc_decode_close,

    .decode = imc_decode_frame,

    .long_name = NULL_IF_CONFIG_SMALL("IMC (Intel Music Coder)"),

};