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/*

 * TwinVQ decoder

 * Copyright (c) 2009 Vitor Sessak

 *

 * 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 

#include 

#include "libavutil/channel_layout.h"

#include "libavutil/float_dsp.h"

#include "avcodec.h"

#include "fft.h"

#include "internal.h"

#include "lsp.h"

#include "sinewin.h"

#include "twinvq.h"

/**

 * Evaluate a single LPC amplitude spectrum envelope coefficient from the line

 * spectrum pairs.

 *

 * @param lsp a vector of the cosine of the LSP values

 * @param cos_val cos(PI*i/N) where i is the index of the LPC amplitude

 * @param order the order of the LSP (and the size of the *lsp buffer). Must

 *        be a multiple of four.

 * @return the LPC value

 *

 * @todo reuse code from Vorbis decoder: vorbis_floor0_decode

 */

static float eval_lpc_spectrum(const float *lsp, float cos_val, int order)

{

    int j;

    float p         = 0.5f;

    float q         = 0.5f;

    float two_cos_w = 2.0f * cos_val;

    for (j = 0; j + 1 < order; j += 2 * 2) {

        // Unroll the loop once since order is a multiple of four

        q *= lsp[j]     - two_cos_w;

        p *= lsp[j + 1] - two_cos_w;

        q *= lsp[j + 2] - two_cos_w;

        p *= lsp[j + 3] - two_cos_w;

    }

    p *= p * (2.0f - two_cos_w);

    q *= q * (2.0f + two_cos_w);

    return 0.5 / (p + q);

}

/**

 * Evaluate the LPC amplitude spectrum envelope from the line spectrum pairs.

 */

static void eval_lpcenv(TwinVQContext *tctx, const float *cos_vals, float *lpc)

{

    int i;

    const TwinVQModeTab *mtab = tctx->mtab;

    int size_s = mtab->size / mtab->fmode[TWINVQ_FT_SHORT].sub;

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

        float cos_i = tctx->cos_tabs[0][i];

        lpc[i]              = eval_lpc_spectrum(cos_vals,  cos_i, mtab->n_lsp);

        lpc[size_s - i - 1] = eval_lpc_spectrum(cos_vals, -cos_i, mtab->n_lsp);

    }

}

static void interpolate(float *out, float v1, float v2, int size)

{

    int i;

    float step = (v1 - v2) / (size + 1);

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

        v2    += step;

        out[i] = v2;

    }

}

static inline float get_cos(int idx, int part, const float *cos_tab, int size)

{

    return part ? -cos_tab[size - idx - 1]

                :  cos_tab[idx];

}

/**

 * Evaluate the LPC amplitude spectrum envelope from the line spectrum pairs.

 * Probably for speed reasons, the coefficients are evaluated as

 * siiiibiiiisiiiibiiiisiiiibiiiisiiiibiiiis ...

 * where s is an evaluated value, i is a value interpolated from the others

 * and b might be either calculated or interpolated, depending on an

 * unexplained condition.

 *

 * @param step the size of a block "siiiibiiii"

 * @param in the cosine of the LSP data

 * @param part is 0 for 0...PI (positive cosine values) and 1 for PI...2PI

 *        (negative cosine values)

 * @param size the size of the whole output

 */

static inline void eval_lpcenv_or_interp(TwinVQContext *tctx,

                                         enum TwinVQFrameType ftype,

                                         float *out, const float *in,

                                         int size, int step, int part)

{

    int i;

    const TwinVQModeTab *mtab = tctx->mtab;

    const float *cos_tab      = tctx->cos_tabs[ftype];

    // Fill the 's'

    for (i = 0; i < size; i += step)

        out[i] =

            eval_lpc_spectrum(in,

                              get_cos(i, part, cos_tab, size),

                              mtab->n_lsp);

    // Fill the 'iiiibiiii'

    for (i = step; i <= size - 2 * step; i += step) {

        if (out[i + step] + out[i - step] > 1.95 * out[i] ||

            out[i + step]                 >= out[i - step]) {

            interpolate(out + i - step + 1, out[i], out[i - step], step - 1);

        } else {

            out[i - step / 2] =

                eval_lpc_spectrum(in,

                                  get_cos(i - step / 2, part, cos_tab, size),

                                  mtab->n_lsp);

            interpolate(out + i - step + 1, out[i - step / 2],

                        out[i - step], step / 2 - 1);

            interpolate(out + i - step / 2 + 1, out[i],

                        out[i - step / 2], step / 2 - 1);

        }

    }

    interpolate(out + size - 2 * step + 1, out[size - step],

                out[size - 2 * step], step - 1);

}

static void eval_lpcenv_2parts(TwinVQContext *tctx, enum TwinVQFrameType ftype,

                               const float *buf, float *lpc,

                               int size, int step)

{

    eval_lpcenv_or_interp(tctx, ftype, lpc, buf, size / 2, step, 0);

    eval_lpcenv_or_interp(tctx, ftype, lpc + size / 2, buf, size / 2,

                          2 * step, 1);

    interpolate(lpc + size / 2 - step + 1, lpc[size / 2],

                lpc[size / 2 - step], step);

    twinvq_memset_float(lpc + size - 2 * step + 1, lpc[size - 2 * step],

                        2 * step - 1);

}

/**

 * Inverse quantization. Read CB coefficients for cb1 and cb2 from the

 * bitstream, sum the corresponding vectors and write the result to *out

 * after permutation.

 */

static void dequant(TwinVQContext *tctx, const uint8_t *cb_bits, float *out,

                    enum TwinVQFrameType ftype,

                    const int16_t *cb0, const int16_t *cb1, int cb_len)

{

    int pos = 0;

    int i, j;

    for (i = 0; i < tctx->n_div[ftype]; i++) {

        int tmp0, tmp1;

        int sign0 = 1;

        int sign1 = 1;

        const int16_t *tab0, *tab1;

        int length = tctx->length[ftype][i >= tctx->length_change[ftype]];

        int bitstream_second_part = (i >= tctx->bits_main_spec_change[ftype]);

        int bits = tctx->bits_main_spec[0][ftype][bitstream_second_part];

        tmp0 = *cb_bits++;

        if (bits == 7) {

            if (tmp0 & 0x40)

                sign0 = -1;

            tmp0 &= 0x3F;

        }

        bits = tctx->bits_main_spec[1][ftype][bitstream_second_part];

        tmp1 = *cb_bits++;

        if (bits == 7) {

            if (tmp1 & 0x40)

                sign1 = -1;

            tmp1 &= 0x3F;

        }

        tab0 = cb0 + tmp0 * cb_len;

        tab1 = cb1 + tmp1 * cb_len;

        for (j = 0; j < length; j++)

            out[tctx->permut[ftype][pos + j]] = sign0 * tab0[j] +

                                                sign1 * tab1[j];

        pos += length;

    }

}

static void dec_gain(TwinVQContext *tctx,

                     enum TwinVQFrameType ftype, float *out)

{

    const TwinVQModeTab   *mtab =  tctx->mtab;

    const TwinVQFrameData *bits = &tctx->bits;

    int i, j;

    int sub        = mtab->fmode[ftype].sub;

    float step     = TWINVQ_AMP_MAX     / ((1 << TWINVQ_GAIN_BITS)     - 1);

    float sub_step = TWINVQ_SUB_AMP_MAX / ((1 << TWINVQ_SUB_GAIN_BITS) - 1);

    if (ftype == TWINVQ_FT_LONG) {

        for (i = 0; i < tctx->avctx->channels; i++)

            out[i] = (1.0 / (1 << 13)) *

                     twinvq_mulawinv(step * 0.5 + step * bits->gain_bits[i],

                                     TWINVQ_AMP_MAX, TWINVQ_MULAW_MU);

    } else {

        for (i = 0; i < tctx->avctx->channels; i++) {

            float val = (1.0 / (1 << 23)) *

                        twinvq_mulawinv(step * 0.5 + step * bits->gain_bits[i],

                                        TWINVQ_AMP_MAX, TWINVQ_MULAW_MU);

            for (j = 0; j < sub; j++)

                out[i * sub + j] =

                    val * twinvq_mulawinv(sub_step * 0.5 +

                                          sub_step * bits->sub_gain_bits[i * sub + j],

                                          TWINVQ_SUB_AMP_MAX, TWINVQ_MULAW_MU);

        }

    }

}

/**

 * Rearrange the LSP coefficients so that they have a minimum distance of

 * min_dist. This function does it exactly as described in section of 3.2.4

 * of the G.729 specification (but interestingly is different from what the

 * reference decoder actually does).

 */

static void rearrange_lsp(int order, float *lsp, float min_dist)

{

    int i;

    float min_dist2 = min_dist * 0.5;

    for (i = 1; i < order; i++)

        if (lsp[i] - lsp[i - 1] < min_dist) {

            float avg = (lsp[i] + lsp[i - 1]) * 0.5;

            lsp[i - 1] = avg - min_dist2;

            lsp[i]     = avg + min_dist2;

        }

}

static void decode_lsp(TwinVQContext *tctx, int lpc_idx1, uint8_t *lpc_idx2,

                       int lpc_hist_idx, float *lsp, float *hist)

{

    const TwinVQModeTab *mtab = tctx->mtab;

    int i, j;

    const float *cb  = mtab->lspcodebook;

    const float *cb2 = cb  + (1 << mtab->lsp_bit1) * mtab->n_lsp;

    const float *cb3 = cb2 + (1 << mtab->lsp_bit2) * mtab->n_lsp;

    const int8_t funny_rounding[4] = {

        -2,

        mtab->lsp_split == 4 ? -2 : 1,

        mtab->lsp_split == 4 ? -2 : 1,

    };

    j = 0;

    for (i = 0; i < mtab->lsp_split; i++) {

        int chunk_end = ((i + 1) * mtab->n_lsp + funny_rounding[i]) /

                        mtab->lsp_split;

        for (; j < chunk_end; j++)

            lsp[j] = cb[lpc_idx1     * mtab->n_lsp + j] +

                     cb2[lpc_idx2[i] * mtab->n_lsp + j];

    }

    rearrange_lsp(mtab->n_lsp, lsp, 0.0001);

    for (i = 0; i < mtab->n_lsp; i++) {

        float tmp1 = 1.0     - cb3[lpc_hist_idx * mtab->n_lsp + i];

        float tmp2 = hist[i] * cb3[lpc_hist_idx * mtab->n_lsp + i];

        hist[i] = lsp[i];

        lsp[i]  = lsp[i] * tmp1 + tmp2;

    }

    rearrange_lsp(mtab->n_lsp, lsp, 0.0001);

    rearrange_lsp(mtab->n_lsp, lsp, 0.000095);

    ff_sort_nearly_sorted_floats(lsp, mtab->n_lsp);

}

static void dec_lpc_spectrum_inv(TwinVQContext *tctx, float *lsp,

                                 enum TwinVQFrameType ftype, float *lpc)

{

    int i;

    int size = tctx->mtab->size / tctx->mtab->fmode[ftype].sub;

    for (i = 0; i < tctx->mtab->n_lsp; i++)

        lsp[i] = 2 * cos(lsp[i]);

    switch (ftype) {

    case TWINVQ_FT_LONG:

        eval_lpcenv_2parts(tctx, ftype, lsp, lpc, size, 8);

        break;

    case TWINVQ_FT_MEDIUM:

        eval_lpcenv_2parts(tctx, ftype, lsp, lpc, size, 2);

        break;

    case TWINVQ_FT_SHORT:

        eval_lpcenv(tctx, lsp, lpc);

        break;

    }

}

static const uint8_t wtype_to_wsize[] = { 0, 0, 2, 2, 2, 1, 0, 1, 1 };

static void imdct_and_window(TwinVQContext *tctx, enum TwinVQFrameType ftype,

                             int wtype, float *in, float *prev, int ch)

{

    FFTContext *mdct = &tctx->mdct_ctx[ftype];

    const TwinVQModeTab *mtab = tctx->mtab;

    int bsize = mtab->size / mtab->fmode[ftype].sub;

    int size  = mtab->size;

    float *buf1 = tctx->tmp_buf;

    int j, first_wsize, wsize; // Window size

    float *out  = tctx->curr_frame + 2 * ch * mtab->size;

    float *out2 = out;

    float *prev_buf;

    int types_sizes[] = {

        mtab->size /  mtab->fmode[TWINVQ_FT_LONG].sub,

        mtab->size /  mtab->fmode[TWINVQ_FT_MEDIUM].sub,

        mtab->size / (mtab->fmode[TWINVQ_FT_SHORT].sub * 2),

    };

    wsize       = types_sizes[wtype_to_wsize[wtype]];

    first_wsize = wsize;

    prev_buf    = prev + (size - bsize) / 2;

    for (j = 0; j < mtab->fmode[ftype].sub; j++) {

        int sub_wtype = ftype == TWINVQ_FT_MEDIUM ? 8 : wtype;

        if (!j && wtype == 4)

            sub_wtype = 4;

        else if (j == mtab->fmode[ftype].sub - 1 && wtype == 7)

            sub_wtype = 7;

        wsize = types_sizes[wtype_to_wsize[sub_wtype]];

        mdct->imdct_half(mdct, buf1 + bsize * j, in + bsize * j);

        tctx->fdsp.vector_fmul_window(out2, prev_buf + (bsize - wsize) / 2,

                                      buf1 + bsize * j,

                                      ff_sine_windows[av_log2(wsize)],

                                      wsize / 2);

        out2 += wsize;

        memcpy(out2, buf1 + bsize * j + wsize / 2,

               (bsize - wsize / 2) * sizeof(float));

        out2 += ftype == TWINVQ_FT_MEDIUM ? (bsize - wsize) / 2 : bsize - wsize;

        prev_buf = buf1 + bsize * j + bsize / 2;

    }

    tctx->last_block_pos[ch] = (size + first_wsize) / 2;

}

static void imdct_output(TwinVQContext *tctx, enum TwinVQFrameType ftype,

                         int wtype, float **out)

{

    const TwinVQModeTab *mtab = tctx->mtab;

    float *prev_buf           = tctx->prev_frame + tctx->last_block_pos[0];

    int size1, size2, i;

    for (i = 0; i < tctx->avctx->channels; i++)

        imdct_and_window(tctx, ftype, wtype,

                         tctx->spectrum + i * mtab->size,

                         prev_buf + 2 * i * mtab->size,

                         i);

    if (!out)

        return;

    size2 = tctx->last_block_pos[0];

    size1 = mtab->size - size2;

    memcpy(&out[0][0],     prev_buf,         size1 * sizeof(out[0][0]));

    memcpy(&out[0][size1], tctx->curr_frame, size2 * sizeof(out[0][0]));

    if (tctx->avctx->channels == 2) {

        memcpy(&out[1][0], &prev_buf[2 * mtab->size],

               size1 * sizeof(out[1][0]));

        memcpy(&out[1][size1], &tctx->curr_frame[2 * mtab->size],

               size2 * sizeof(out[1][0]));

        tctx->fdsp.butterflies_float(out[0], out[1], mtab->size);

    }

}

static void read_and_decode_spectrum(TwinVQContext *tctx, float *out,

                                     enum TwinVQFrameType ftype)

{

    const TwinVQModeTab *mtab = tctx->mtab;

    TwinVQFrameData *bits     = &tctx->bits;

    int channels              = tctx->avctx->channels;

    int sub        = mtab->fmode[ftype].sub;

    int block_size = mtab->size / sub;

    float gain[TWINVQ_CHANNELS_MAX * TWINVQ_SUBBLOCKS_MAX];

    float ppc_shape[TWINVQ_PPC_SHAPE_LEN_MAX * TWINVQ_CHANNELS_MAX * 4];

    int i, j;

    dequant(tctx, bits->main_coeffs, out, ftype,

            mtab->fmode[ftype].cb0, mtab->fmode[ftype].cb1,

            mtab->fmode[ftype].cb_len_read);

    dec_gain(tctx, ftype, gain);

    if (ftype == TWINVQ_FT_LONG) {

        int cb_len_p = (tctx->n_div[3] + mtab->ppc_shape_len * channels - 1) /

                       tctx->n_div[3];

        dequant(tctx, bits->ppc_coeffs, ppc_shape,

                TWINVQ_FT_PPC, mtab->ppc_shape_cb,

                mtab->ppc_shape_cb + cb_len_p * TWINVQ_PPC_SHAPE_CB_SIZE,

                cb_len_p);

    }

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

        float *chunk = out + mtab->size * i;

        float lsp[TWINVQ_LSP_COEFS_MAX];

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

            tctx->dec_bark_env(tctx, bits->bark1[i][j],

                               bits->bark_use_hist[i][j], i,

                               tctx->tmp_buf, gain[sub * i + j], ftype);

            tctx->fdsp.vector_fmul(chunk + block_size * j,

                                   chunk + block_size * j,

                                   tctx->tmp_buf, block_size);

        }

        if (ftype == TWINVQ_FT_LONG)

            tctx->decode_ppc(tctx, bits->p_coef[i], bits->g_coef[i],

                             ppc_shape + i * mtab->ppc_shape_len, chunk);

        decode_lsp(tctx, bits->lpc_idx1[i], bits->lpc_idx2[i],

                   bits->lpc_hist_idx[i], lsp, tctx->lsp_hist[i]);

        dec_lpc_spectrum_inv(tctx, lsp, ftype, tctx->tmp_buf);

        for (j = 0; j < mtab->fmode[ftype].sub; j++) {

            tctx->fdsp.vector_fmul(chunk, chunk, tctx->tmp_buf, block_size);

            chunk += block_size;

        }

    }

}

const enum TwinVQFrameType ff_twinvq_wtype_to_ftype_table[] = {

    TWINVQ_FT_LONG,   TWINVQ_FT_LONG, TWINVQ_FT_SHORT, TWINVQ_FT_LONG,

    TWINVQ_FT_MEDIUM, TWINVQ_FT_LONG, TWINVQ_FT_LONG,  TWINVQ_FT_MEDIUM,

    TWINVQ_FT_MEDIUM

};

int ff_twinvq_decode_frame(AVCodecContext *avctx, void *data,

                           int *got_frame_ptr, AVPacket *avpkt)

{

    AVFrame *frame     = data;

    const uint8_t *buf = avpkt->data;

    int buf_size       = avpkt->size;

    TwinVQContext *tctx = avctx->priv_data;

    const TwinVQModeTab *mtab = tctx->mtab;

    float **out = NULL;

    int ret;

    /* get output buffer */

    if (tctx->discarded_packets >= 2) {

        frame->nb_samples = mtab->size;

        if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)

            return ret;

        out = (float **)frame->extended_data;

    }

    if (buf_size < avctx->block_align) {

        av_log(avctx, AV_LOG_ERROR,

               "Frame too small (%d bytes). Truncated file?\n", buf_size);

        return AVERROR(EINVAL);

    }

    if ((ret = tctx->read_bitstream(avctx, tctx, buf, buf_size)) < 0)

        return ret;

    read_and_decode_spectrum(tctx, tctx->spectrum, tctx->bits.ftype);

    imdct_output(tctx, tctx->bits.ftype, tctx->bits.window_type, out);

    FFSWAP(float *, tctx->curr_frame, tctx->prev_frame);

    if (tctx->discarded_packets < 2) {

        tctx->discarded_packets++;

        *got_frame_ptr = 0;

        return buf_size;

    }

    *got_frame_ptr = 1;

    return ret;

}

/**

 * Init IMDCT and windowing tables

 */

static av_cold int init_mdct_win(TwinVQContext *tctx)

{

    int i, j, ret;

    const TwinVQModeTab *mtab = tctx->mtab;

    int size_s = mtab->size / mtab->fmode[TWINVQ_FT_SHORT].sub;

    int size_m = mtab->size / mtab->fmode[TWINVQ_FT_MEDIUM].sub;

    int channels = tctx->avctx->channels;

    float norm = channels == 1 ? 2.0 : 1.0;

    for (i = 0; i < 3; i++) {

        int bsize = tctx->mtab->size / tctx->mtab->fmode[i].sub;

        if ((ret = ff_mdct_init(&tctx->mdct_ctx[i], av_log2(bsize) + 1, 1,

                                -sqrt(norm / bsize) / (1 << 15))))

            return ret;

    }

    FF_ALLOC_OR_GOTO(tctx->avctx, tctx->tmp_buf,

                     mtab->size * sizeof(*tctx->tmp_buf), alloc_fail);

    FF_ALLOC_OR_GOTO(tctx->avctx, tctx->spectrum,

                     2 * mtab->size * channels * sizeof(*tctx->spectrum),

                     alloc_fail);

    FF_ALLOC_OR_GOTO(tctx->avctx, tctx->curr_frame,

                     2 * mtab->size * channels * sizeof(*tctx->curr_frame),

                     alloc_fail);

    FF_ALLOC_OR_GOTO(tctx->avctx, tctx->prev_frame,

                     2 * mtab->size * channels * sizeof(*tctx->prev_frame),

                     alloc_fail);

    for (i = 0; i < 3; i++) {

        int m       = 4 * mtab->size / mtab->fmode[i].sub;

        double freq = 2 * M_PI / m;

        FF_ALLOC_OR_GOTO(tctx->avctx, tctx->cos_tabs[i],

                         (m / 4) * sizeof(*tctx->cos_tabs[i]), alloc_fail);

        for (j = 0; j <= m / 8; j++)

            tctx->cos_tabs[i][j] = cos((2 * j + 1) * freq);

        for (j = 1; j < m / 8; j++)

            tctx->cos_tabs[i][m / 4 - j] = tctx->cos_tabs[i][j];

    }

    ff_init_ff_sine_windows(av_log2(size_m));

    ff_init_ff_sine_windows(av_log2(size_s / 2));

    ff_init_ff_sine_windows(av_log2(mtab->size));

    return 0;

alloc_fail:

    return AVERROR(ENOMEM);

}

/**

 * Interpret the data as if it were a num_blocks x line_len[0] matrix and for

 * each line do a cyclic permutation, i.e.

 * abcdefghijklm -> defghijklmabc

 * where the amount to be shifted is evaluated depending on the column.

 */

static void permutate_in_line(int16_t *tab, int num_vect, int num_blocks,

                              int block_size,

                              const uint8_t line_len[2], int length_div,

                              enum TwinVQFrameType ftype)

{

    int i, j;

    for (i = 0; i < line_len[0]; i++) {

        int shift;

        if (num_blocks == 1                                    ||

            (ftype == TWINVQ_FT_LONG && num_vect % num_blocks) ||

            (ftype != TWINVQ_FT_LONG && num_vect & 1)          ||

            i == line_len[1]) {

            shift = 0;

        } else if (ftype == TWINVQ_FT_LONG) {

            shift = i;

        } else

            shift = i * i;

        for (j = 0; j < num_vect && (j + num_vect * i < block_size * num_blocks); j++)

            tab[i * num_vect + j] = i * num_vect + (j + shift) % num_vect;

    }

}

/**

 * Interpret the input data as in the following table:

 *

 * @verbatim

 *

 * abcdefgh

 * ijklmnop

 * qrstuvw

 * x123456

 *

 * @endverbatim

 *

 * and transpose it, giving the output

 * aiqxbjr1cks2dlt3emu4fvn5gow6hp

 */

static void transpose_perm(int16_t *out, int16_t *in, int num_vect,

                           const uint8_t line_len[2], int length_div)

{

    int i, j;

    int cont = 0;

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

        for (j = 0; j < line_len[i >= length_div]; j++)

            out[cont++] = in[j * num_vect + i];

}

static void linear_perm(int16_t *out, int16_t *in, int n_blocks, int size)

{

    int block_size = size / n_blocks;

    int i;

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

        out[i] = block_size * (in[i] % n_blocks) + in[i] / n_blocks;

}

static av_cold void construct_perm_table(TwinVQContext *tctx,

                                         enum TwinVQFrameType ftype)

{

    int block_size, size;

    const TwinVQModeTab *mtab = tctx->mtab;

    int16_t *tmp_perm = (int16_t *)tctx->tmp_buf;

    if (ftype == TWINVQ_FT_PPC) {

        size       = tctx->avctx->channels;

        block_size = mtab->ppc_shape_len;

    } else {

        size       = tctx->avctx->channels * mtab->fmode[ftype].sub;

        block_size = mtab->size / mtab->fmode[ftype].sub;

    }

    permutate_in_line(tmp_perm, tctx->n_div[ftype], size,

                      block_size, tctx->length[ftype],

                      tctx->length_change[ftype], ftype);

    transpose_perm(tctx->permut[ftype], tmp_perm, tctx->n_div[ftype],

                   tctx->length[ftype], tctx->length_change[ftype]);

    linear_perm(tctx->permut[ftype], tctx->permut[ftype], size,

                size * block_size);

}

static av_cold void init_bitstream_params(TwinVQContext *tctx)

{

    const TwinVQModeTab *mtab = tctx->mtab;

    int n_ch                  = tctx->avctx->channels;

    int total_fr_bits         = tctx->avctx->bit_rate * mtab->size /

                                tctx->avctx->sample_rate;

    int lsp_bits_per_block = n_ch * (mtab->lsp_bit0 + mtab->lsp_bit1 +

                                     mtab->lsp_split * mtab->lsp_bit2);

    int ppc_bits = n_ch * (mtab->pgain_bit + mtab->ppc_shape_bit +

                           mtab->ppc_period_bit);

    int bsize_no_main_cb[3], bse_bits[3], i;

    enum TwinVQFrameType frametype;

    for (i = 0; i < 3; i++)

        // +1 for history usage switch

        bse_bits[i] = n_ch *

                      (mtab->fmode[i].bark_n_coef *

                       mtab->fmode[i].bark_n_bit + 1);

    bsize_no_main_cb[2] = bse_bits[2] + lsp_bits_per_block + ppc_bits +

                          TWINVQ_WINDOW_TYPE_BITS + n_ch * TWINVQ_GAIN_BITS;

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

        bsize_no_main_cb[i] =

            lsp_bits_per_block + n_ch * TWINVQ_GAIN_BITS +

            TWINVQ_WINDOW_TYPE_BITS +

            mtab->fmode[i].sub * (bse_bits[i] + n_ch * TWINVQ_SUB_GAIN_BITS);

    if (tctx->codec == TWINVQ_CODEC_METASOUND) {

        bsize_no_main_cb[1] += 2;

        bsize_no_main_cb[2] += 2;

    }

    // The remaining bits are all used for the main spectrum coefficients

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

        int bit_size, vect_size;

        int rounded_up, rounded_down, num_rounded_down, num_rounded_up;

        if (i == 3) {

            bit_size  = n_ch * mtab->ppc_shape_bit;

            vect_size = n_ch * mtab->ppc_shape_len;

        } else {

            bit_size  = total_fr_bits - bsize_no_main_cb[i];

            vect_size = n_ch * mtab->size;

        }

        tctx->n_div[i] = (bit_size + 13) / 14;

        rounded_up                     = (bit_size + tctx->n_div[i] - 1) /

                                         tctx->n_div[i];

        rounded_down                   = (bit_size) / tctx->n_div[i];

        num_rounded_down               = rounded_up * tctx->n_div[i] - bit_size;

        num_rounded_up                 = tctx->n_div[i] - num_rounded_down;

        tctx->bits_main_spec[0][i][0]  = (rounded_up + 1)   / 2;

        tctx->bits_main_spec[1][i][0]  =  rounded_up        / 2;

        tctx->bits_main_spec[0][i][1]  = (rounded_down + 1) / 2;

        tctx->bits_main_spec[1][i][1]  =  rounded_down      / 2;

        tctx->bits_main_spec_change[i] = num_rounded_up;

        rounded_up             = (vect_size + tctx->n_div[i] - 1) /

                                 tctx->n_div[i];

        rounded_down           = (vect_size) / tctx->n_div[i];

        num_rounded_down       = rounded_up * tctx->n_div[i] - vect_size;

        num_rounded_up         = tctx->n_div[i] - num_rounded_down;

        tctx->length[i][0]     = rounded_up;

        tctx->length[i][1]     = rounded_down;

        tctx->length_change[i] = num_rounded_up;

    }

    for (frametype = TWINVQ_FT_SHORT; frametype <= TWINVQ_FT_PPC; frametype++)

        construct_perm_table(tctx, frametype);

}

av_cold int ff_twinvq_decode_close(AVCodecContext *avctx)

{

    TwinVQContext *tctx = avctx->priv_data;

    int i;

    for (i = 0; i < 3; i++) {

        ff_mdct_end(&tctx->mdct_ctx[i]);

        av_free(tctx->cos_tabs[i]);

    }

    av_free(tctx->curr_frame);

    av_free(tctx->spectrum);

    av_free(tctx->prev_frame);

    av_free(tctx->tmp_buf);

    return 0;

}

av_cold int ff_twinvq_decode_init(AVCodecContext *avctx)

{

    int ret;

    TwinVQContext *tctx = avctx->priv_data;

    tctx->avctx       = avctx;

    avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;

    avpriv_float_dsp_init(&tctx->fdsp, avctx->flags & CODEC_FLAG_BITEXACT);

    if ((ret = init_mdct_win(tctx))) {

        av_log(avctx, AV_LOG_ERROR, "Error initializing MDCT\n");

        ff_twinvq_decode_close(avctx);

        return ret;

    }

    init_bitstream_params(tctx);

    twinvq_memset_float(tctx->bark_hist[0][0], 0.1,

                        FF_ARRAY_ELEMS(tctx->bark_hist));

    return 0;

}