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FFmpeg/libavcodec/imc.c

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  1. /*

  2.  * IMC compatible decoder

  3.  * Copyright (c) 2002-2004 Maxim Poliakovski

  4.  * Copyright (c) 2006 Benjamin Larsson

  5.  * Copyright (c) 2006 Konstantin Shishkov

  6.  *

  7.  * This file is part of FFmpeg.

  8.  *

  9.  * FFmpeg is free software; you can redistribute it and/or

  10.  * modify it under the terms of the GNU Lesser General Public

  11.  * License as published by the Free Software Foundation; either

  12.  * version 2.1 of the License, or (at your option) any later version.

  13.  *

  14.  * FFmpeg is distributed in the hope that it will be useful,

  15.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  16.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  17.  * Lesser General Public License for more details.

  18.  *

  19.  * You should have received a copy of the GNU Lesser General Public

  20.  * License along with FFmpeg; if not, write to the Free Software

  21.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  22.  */

  23. 

  24. /**

  25.  *  @file imc.c IMC - Intel Music Coder

  26.  *  A mdct based codec using a 256 points large transform

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

  28.  *  Only mono is supported.

  29.  *

  30.  */

  31. 

  32. 

  33. #include <math.h>

  34. #include <stddef.h>

  35. #include <stdio.h>

  36. 

  37. #define ALT_BITSTREAM_READER

  38. #include "avcodec.h"

  39. #include "bitstream.h"

  40. #include "dsputil.h"

  41. 

  42. #include "imcdata.h"

  43. 

  44. #define IMC_BLOCK_SIZE 64

  45. #define IMC_FRAME_ID 0x21

  46. #define BANDS 32

  47. #define COEFFS 256

  48. 

  49. typedef struct {

  50.     float old_floor[BANDS];

  51.     float flcoeffs1[BANDS];

  52.     float flcoeffs2[BANDS];

  53.     float flcoeffs3[BANDS];

  54.     float flcoeffs4[BANDS];

  55.     float flcoeffs5[BANDS];

  56.     float flcoeffs6[BANDS];

  57.     float CWdecoded[COEFFS];

  58. 

  59.     /** MDCT tables */

  60.     //@{

  61.     float mdct_sine_window[COEFFS];

  62.     float post_cos[COEFFS];

  63.     float post_sin[COEFFS];

  64.     float pre_coef1[COEFFS];

  65.     float pre_coef2[COEFFS];

  66.     float last_fft_im[COEFFS];

  67.     //@}

  68. 

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

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

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

  72.     int levlCoeffBuf[BANDS];

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

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

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

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

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

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

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

  80.     float sqrt_tab[30];

  81.     GetBitContext gb;

  82.     int decoder_reset;

  83.     float one_div_log2;

  84. 

  85.     DSPContext dsp;

  86.     FFTContext fft;

  87.     DECLARE_ALIGNED_16(FFTComplex, samples[COEFFS/2]);

  88.     DECLARE_ALIGNED_16(float, out_samples[COEFFS]);

  89. } IMCContext;

  90. 

  91. static VLC huffman_vlc[4][4];

  92. 

  93. #define VLC_TABLES_SIZE 9512

  94. 

  95. static const int vlc_offsets[17] = {

  96.     0,     640, 1156, 1732, 2308, 2852, 3396, 3924,

  97.     4452, 5220, 5860, 6628, 7268, 7908, 8424, 8936, VLC_TABLES_SIZE};

  98. 

  99. static VLC_TYPE vlc_tables[VLC_TABLES_SIZE][2];

  100. 

  101. static av_cold int imc_decode_init(AVCodecContext * avctx)

  102. {

  103.     int i, j;

  104.     IMCContext *q = avctx->priv_data;

  105.     double r1, r2;

  106. 

  107.     q->decoder_reset = 1;

  108. 

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

  110.         q->old_floor[i] = 1.0;

  111. 

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

  113.     ff_sine_window_init(q->mdct_sine_window, COEFFS);

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

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

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

  117.         q->post_cos[i] = cos(i / 256.0 * M_PI);

  118.         q->post_sin[i] = sin(i / 256.0 * M_PI);

  119. 

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

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

  122. 

  123.         if (i & 0x1)

  124.         {

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

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

  127.         }

  128.         else

  129.         {

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

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

  132.         }

  133. 

  134.         q->last_fft_im[i] = 0;

  135.     }

  136. 

  137.     /* Generate a square root table */

  138. 

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

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

  141.     }

  142. 

  143.     /* initialize the VLC tables */

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

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

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

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

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

  149.                      imc_huffman_lens[i][j], 1, 1,

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

  151.         }

  152.     }

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

  154. 

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

  156.     dsputil_init(&q->dsp, avctx);

  157.     return 0;

  158. }

  159. 

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

  161.                                 float* flcoeffs3, float* flcoeffs5)

  162. {

  163.     float   workT1[BANDS];

  164.     float   workT2[BANDS];

  165.     float   workT3[BANDS];

  166.     float   snr_limit = 1.e-30;

  167.     float   accum = 0.0;

  168.     int i, cnt2;

  169. 

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

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

  172.         if (bandWidthT[i]){

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

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

  175.         } else {

  176.             workT1[i] = 0.0;

  177.             flcoeffs3[i] = -30000.0;

  178.         }

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

  180.         if (workT3[i] <= snr_limit)

  181.             workT3[i] = 0.0;

  182.     }

  183. 

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

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

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

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

  188.     }

  189. 

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

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

  192.         flcoeffs5[i] += accum;

  193.     }

  194. 

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

  196.         workT2[i] = 0.0;

  197. 

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

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

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

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

  202.     }

  203. 

  204.     accum = 0.0;

  205. 

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

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

  208.         flcoeffs5[i] += accum;

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

  210.     }

  211. }

  212. 

  213. 

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

  215. {

  216.     int i;

  217.     VLC *hufftab[4];

  218.     int start = 0;

  219.     const uint8_t *cb_sel;

  220.     int s;

  221. 

  222.     s = stream_format_code >> 1;

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

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

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

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

  227.     cb_sel = imc_cb_select[s];

  228. 

  229.     if(stream_format_code & 4)

  230.         start = 1;

  231.     if(start)

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

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

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

  235.         if(levlCoeffs[i] == 17)

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

  237.     }

  238. }

  239. 

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

  241.                                          float* flcoeffs2)

  242. {

  243.     int i, level;

  244.     float tmp, tmp2;

  245.     //maybe some frequency division thingy

  246. 

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

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

  249.     tmp = flcoeffs1[0];

  250.     tmp2 = flcoeffs2[0];

  251. 

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

  253.         level = levlCoeffBuf[i];

  254.         if (level == 16) {

  255.             flcoeffs1[i] = 1.0;

  256.             flcoeffs2[i] = 0.0;

  257.         } else {

  258.             if (level < 17)

  259.                 level -=7;

  260.             else if (level <= 24)

  261.                 level -=32;

  262.             else

  263.                 level -=16;

  264. 

  265.             tmp  *= imc_exp_tab[15 + level];

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

  267.             flcoeffs1[i] = tmp;

  268.             flcoeffs2[i] = tmp2;

  269.         }

  270.     }

  271. }

  272. 

  273. 

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

  275.                                           float* flcoeffs2) {

  276.     int i;

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

  278.         //      and flcoeffs2 old scale factors

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

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

  281.         flcoeffs1[i] = 0;

  282.         if(levlCoeffBuf[i] < 16) {

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

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

  285.         } else {

  286.             flcoeffs1[i] = old_floor[i];

  287.         }

  288.     }

  289. }

  290. 

  291. /**

  292.  * Perform bit allocation depending on bits available

  293.  */

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

  295.     int i, j;

  296.     const float limit = -1.e20;

  297.     float highest = 0.0;

  298.     int indx;

  299.     int t1 = 0;

  300.     int t2 = 1;

  301.     float summa = 0.0;

  302.     int iacc = 0;

  303.     int summer = 0;

  304.     int rres, cwlen;

  305.     float lowest = 1.e10;

  306.     int low_indx = 0;

  307.     float workT[32];

  308.     int flg;

  309.     int found_indx = 0;

  310. 

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

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

  313. 

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

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

  316.     }

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

  318. 

  319.     highest = highest * 0.25;

  320. 

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

  322.         indx = -1;

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

  324.             indx = 0;

  325. 

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

  327.             indx = 1;

  328. 

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

  330.             indx = 2;

  331. 

  332.         if (indx == -1)

  333.             return -1;

  334. 

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

  336.     }

  337. 

  338.     if (stream_format_code & 0x2) {

  339.         q->flcoeffs4[0] = limit;

  340.         q->flcoeffs4[1] = limit;

  341.         q->flcoeffs4[2] = limit;

  342.         q->flcoeffs4[3] = limit;

  343.     }

  344. 

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

  346.         iacc += q->bandWidthT[i];

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

  348.     }

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

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

  351. 

  352. 

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

  354.         rres = summer - freebits;

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

  356. 

  357.         summer = 0;

  358.         iacc = 0;

  359. 

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

  361.             cwlen = av_clip((int)((q->flcoeffs4[j] * 0.5) - summa + 0.5), 0, 6);

  362. 

  363.             q->bitsBandT[j] = cwlen;

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

  365. 

  366.             if (cwlen > 0)

  367.                 iacc += q->bandWidthT[j];

  368.         }

  369. 

  370.         flg = t2;

  371.         t2 = 1;

  372.         if (freebits < summer)

  373.             t2 = -1;

  374.         if (i == 0)

  375.             flg = t2;

  376.         if(flg != t2)

  377.             t1++;

  378. 

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

  380.     }

  381. 

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

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

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

  385.     }

  386. 

  387.     if (freebits > summer) {

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

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

  390.         }

  391. 

  392.         highest = 0.0;

  393. 

  394.         do{

  395.             if (highest <= -1.e20)

  396.                 break;

  397. 

  398.             found_indx = 0;

  399.             highest = -1.e20;

  400. 

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

  402.                 if (workT[i] > highest) {

  403.                     highest = workT[i];

  404.                     found_indx = i;

  405.                 }

  406.             }

  407. 

  408.             if (highest > -1.e20) {

  409.                 workT[found_indx] -= 2.0;

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

  411.                     workT[found_indx] = -1.e20;

  412. 

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

  414.                     q->CWlengthT[j]++;

  415.                     summer++;

  416.                 }

  417.             }

  418.         }while (freebits > summer);

  419.     }

  420.     if (freebits < summer) {

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

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

  423.         }

  424.         if (stream_format_code & 0x2) {

  425.             workT[0] = 1.e20;

  426.             workT[1] = 1.e20;

  427.             workT[2] = 1.e20;

  428.             workT[3] = 1.e20;

  429.         }

  430.         while (freebits < summer){

  431.             lowest = 1.e10;

  432.             low_indx = 0;

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

  434.                 if (workT[i] < lowest) {

  435.                     lowest = workT[i];

  436.                     low_indx = i;

  437.                 }

  438.             }

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

  440.             workT[low_indx] = lowest + 2.0;

  441. 

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

  443.                 workT[low_indx] = 1.e20;

  444. 

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

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

  447.                     q->CWlengthT[j]--;

  448.                     summer--;

  449.                 }

  450.             }

  451.         }

  452.     }

  453.     return 0;

  454. }

  455. 

  456. static void imc_get_skip_coeff(IMCContext* q) {

  457.     int i, j;

  458. 

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

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

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

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

  463.             continue;

  464. 

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

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

  467. 

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

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

  470.                     q->skipFlagCount[i]++;

  471.             }

  472.         } else {

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

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

  475.                     q->skipFlagBits[i]++;

  476.                     q->skipFlags[j]=1;

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

  478.                     q->skipFlagCount[i] += 2;

  479.                 }else{

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

  481.                         q->skipFlagBits[i] +=2;

  482.                         q->skipFlags[j]=0;

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

  484.                         q->skipFlagCount[i]++;

  485.                     }else{

  486.                         q->skipFlagBits[i] +=3;

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

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

  489.                             q->skipFlags[j]=1;

  490.                             q->skipFlagCount[i]++;

  491.                         }else{//101

  492.                             q->skipFlags[j]=0;

  493.                         }

  494.                     }

  495.                 }

  496.             }

  497. 

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

  499.                 q->skipFlagBits[i]++;

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

  501.                     q->skipFlagCount[i]++;

  502.             }

  503.         }

  504.     }

  505. }

  506. 

  507. /**

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

  509.  */

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

  511.     float workT[32];

  512.     int corrected = 0;

  513.     int i, j;

  514.     float highest = 0;

  515.     int found_indx=0;

  516. 

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

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

  519.     }

  520. 

  521.     while (corrected < summer) {

  522.         if(highest <= -1.e20)

  523.             break;

  524. 

  525.         highest = -1.e20;

  526. 

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

  528.             if (workT[i] > highest) {

  529.                 highest = workT[i];

  530.                 found_indx = i;

  531.             }

  532.         }

  533. 

  534.         if (highest > -1.e20) {

  535.             workT[found_indx] -= 2.0;

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

  537.                 workT[found_indx] = -1.e20;

  538. 

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

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

  541.                     q->CWlengthT[j]++;

  542.                     corrected++;

  543.                 }

  544.             }

  545.         }

  546.     }

  547. }

  548. 

  549. static void imc_imdct256(IMCContext *q) {

  550.     int i;

  551.     float re, im;

  552. 

  553.     /* prerotation */

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

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

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

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

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

  559.     }

  560. 

  561.     /* FFT */

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

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

  564. 

  565.     /* postrotation, window and reorder */

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

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

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

  569.         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);

  570.         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);

  571.         q->last_fft_im[i] = im;

  572.     }

  573. }

  574. 

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

  576.     int i, j;

  577.     int middle_value, cw_len, max_size;

  578.     const float* quantizer;

  579. 

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

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

  582.             q->CWdecoded[j] = 0;

  583.             cw_len = q->CWlengthT[j];

  584. 

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

  586.                 continue;

  587. 

  588.             max_size = 1 << cw_len;

  589.             middle_value = max_size >> 1;

  590. 

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

  592.                 return -1;

  593. 

  594.             if (cw_len >= 4){

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

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

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

  598.                 else

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

  600.             }else{

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

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

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

  604.                 else

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

  606.             }

  607.         }

  608.     }

  609.     return 0;

  610. }

  611. 

  612. 

  613. static int imc_get_coeffs (IMCContext* q) {

  614.     int i, j, cw_len, cw;

  615. 

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

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

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

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

  620.                 cw_len = q->CWlengthT[j];

  621.                 cw = 0;

  622. 

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

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

  625.                     return -1;

  626.                 }

  627. 

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

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

  630. 

  631.                 q->codewords[j] = cw;

  632.             }

  633.         }

  634.     }

  635.     return 0;

  636. }

  637. 

  638. static int imc_decode_frame(AVCodecContext * avctx,

  639.                             void *data, int *data_size,

  640.                             const uint8_t * buf, int buf_size)

  641. {

  642. 

  643.     IMCContext *q = avctx->priv_data;

  644. 

  645.     int stream_format_code;

  646.     int imc_hdr, i, j;

  647.     int flag;

  648.     int bits, summer;

  649.     int counter, bitscount;

  650.     uint16_t buf16[IMC_BLOCK_SIZE / 2];

  651. 

  652.     if (buf_size < IMC_BLOCK_SIZE) {

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

  654.         return -1;

  655.     }

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

  657.         buf16[i] = bswap_16(((const uint16_t*)buf)[i]);

  658. 

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

  660. 

  661.     /* Check the frame header */

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

  663.     if (imc_hdr != IMC_FRAME_ID) {

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

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

  666.         return -1;

  667.     }

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

  669. 

  670.     if(stream_format_code & 1){

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

  672.         return -1;

  673.     }

  674. 

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

  676. 

  677.     if (stream_format_code & 0x04)

  678.         q->decoder_reset = 1;

  679. 

  680.     if(q->decoder_reset) {

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

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

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

  684.         q->decoder_reset = 0;

  685.     }

  686. 

  687.     flag = get_bits1(&q->gb);

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

  689. 

  690.     if (stream_format_code & 0x4)

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

  692.     else

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

  694. 

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

  696. 

  697.     counter = 0;

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

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

  700.             q->bandWidthT[i] = 0;

  701.             counter++;

  702.         } else

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

  704.     }

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

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

  707.         if (q->bandWidthT[i])

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

  709.     }

  710. 

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

  712. 

  713.     bitscount = 0;

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

  715.     if (stream_format_code & 0x2) {

  716.         bitscount += 15;

  717. 

  718.         q->bitsBandT[0] = 5;

  719.         q->CWlengthT[0] = 5;

  720.         q->CWlengthT[1] = 5;

  721.         q->CWlengthT[2] = 5;

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

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

  724.             q->bitsBandT[i] = bits;

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

  726.                 q->CWlengthT[j] = bits;

  727.                 bitscount += bits;

  728.             }

  729.         }

  730.     }

  731. 

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

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

  734.         q->decoder_reset = 1;

  735.         return -1;

  736.     }

  737. 

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

  739.         q->sumLenArr[i] = 0;

  740.         q->skipFlagRaw[i] = 0;

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

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

  743.         if (q->bandFlagsBuf[i])

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

  745.                 q->skipFlagRaw[i] = 1;

  746.     }

  747. 

  748.     imc_get_skip_coeff(q);

  749. 

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

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

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

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

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

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

  756.         }

  757.     }

  758. 

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

  760.     bits = summer = 0;

  761. 

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

  763.         if (q->bandFlagsBuf[i]) {

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

  765.                 if(q->skipFlags[j]) {

  766.                     summer += q->CWlengthT[j];

  767.                     q->CWlengthT[j] = 0;

  768.                 }

  769.             }

  770.             bits += q->skipFlagBits[i];

  771.             summer -= q->skipFlagBits[i];

  772.         }

  773.     }

  774.     imc_adjust_bit_allocation(q, summer);

  775. 

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

  777.         q->sumLenArr[i] = 0;

  778. 

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

  780.             if (!q->skipFlags[j])

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

  782.     }

  783. 

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

  785. 

  786.     if(imc_get_coeffs(q) < 0) {

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

  788.         q->decoder_reset = 1;

  789.         return 0;

  790.     }

  791. 

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

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

  794.         q->decoder_reset = 1;

  795.         return 0;

  796.     }

  797. 

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

  799. 

  800.     imc_imdct256(q);

  801. 

  802.     q->dsp.float_to_int16(data, q->out_samples, COEFFS);

  803. 

  804.     *data_size = COEFFS * sizeof(int16_t);

  805. 

  806.     return IMC_BLOCK_SIZE;

  807. }

  808. 

  809. 

  810. static av_cold int imc_decode_close(AVCodecContext * avctx)

  811. {

  812.     IMCContext *q = avctx->priv_data;

  813. 

  814.     ff_fft_end(&q->fft);

  815.     return 0;

  816. }

  817. 

  818. 

  819. AVCodec imc_decoder = {

  820.     .name = "imc",

  821.     .type = CODEC_TYPE_AUDIO,

  822.     .id = CODEC_ID_IMC,

  823.     .priv_data_size = sizeof(IMCContext),

  824.     .init = imc_decode_init,

  825.     .close = imc_decode_close,

  826.     .decode = imc_decode_frame,

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

  828. };