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FFmpeg/libavcodec/alsdec.c

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  1. /*

  2.  * MPEG-4 ALS decoder

  3.  * Copyright (c) 2009 Thilo Borgmann <thilo.borgmann _at_ googlemail.com>

  4.  *

  5.  * This file is part of FFmpeg.

  6.  *

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

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

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

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

  11.  *

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

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

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

  15.  * Lesser General Public License for more details.

  16.  *

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

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

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

  20.  */

  21. 

  22. /**

  23.  * @file libavcodec/alsdec.c

  24.  * MPEG-4 ALS decoder

  25.  * @author Thilo Borgmann <thilo.borgmann _at_ googlemail.com>

  26.  */

  27. 

  28. 

  29. //#define DEBUG

  30. 

  31. 

  32. #include "avcodec.h"

  33. #include "get_bits.h"

  34. #include "unary.h"

  35. #include "mpeg4audio.h"

  36. #include "bytestream.h"

  37. #include "bgmc.h"

  38. 

  39. #include <stdint.h>

  40. 

  41. /** Rice parameters and corresponding index offsets for decoding the

  42.  *  indices of scaled PARCOR values. The table choosen is set globally

  43.  *  by the encoder and stored in ALSSpecificConfig.

  44.  */

  45. static const int8_t parcor_rice_table[3][20][2] = {

  46.     { {-52, 4}, {-29, 5}, {-31, 4}, { 19, 4}, {-16, 4},

  47.       { 12, 3}, { -7, 3}, {  9, 3}, { -5, 3}, {  6, 3},

  48.       { -4, 3}, {  3, 3}, { -3, 2}, {  3, 2}, { -2, 2},

  49.       {  3, 2}, { -1, 2}, {  2, 2}, { -1, 2}, {  2, 2} },

  50.     { {-58, 3}, {-42, 4}, {-46, 4}, { 37, 5}, {-36, 4},

  51.       { 29, 4}, {-29, 4}, { 25, 4}, {-23, 4}, { 20, 4},

  52.       {-17, 4}, { 16, 4}, {-12, 4}, { 12, 3}, {-10, 4},

  53.       {  7, 3}, { -4, 4}, {  3, 3}, { -1, 3}, {  1, 3} },

  54.     { {-59, 3}, {-45, 5}, {-50, 4}, { 38, 4}, {-39, 4},

  55.       { 32, 4}, {-30, 4}, { 25, 3}, {-23, 3}, { 20, 3},

  56.       {-20, 3}, { 16, 3}, {-13, 3}, { 10, 3}, { -7, 3},

  57.       {  3, 3}, {  0, 3}, { -1, 3}, {  2, 3}, { -1, 2} }

  58. };

  59. 

  60. 

  61. /** Scaled PARCOR values used for the first two PARCOR coefficients.

  62.  *  To be indexed by the Rice coded indices.

  63.  *  Generated by: parcor_scaled_values[i] = 32 + ((i * (i+1)) << 7) - (1 << 20)

  64.  *  Actual values are divided by 32 in order to be stored in 16 bits.

  65.  */

  66. static const int16_t parcor_scaled_values[] = {

  67.     -1048544 / 32, -1048288 / 32, -1047776 / 32, -1047008 / 32,

  68.     -1045984 / 32, -1044704 / 32, -1043168 / 32, -1041376 / 32,

  69.     -1039328 / 32, -1037024 / 32, -1034464 / 32, -1031648 / 32,

  70.     -1028576 / 32, -1025248 / 32, -1021664 / 32, -1017824 / 32,

  71.     -1013728 / 32, -1009376 / 32, -1004768 / 32,  -999904 / 32,

  72.      -994784 / 32,  -989408 / 32,  -983776 / 32,  -977888 / 32,

  73.      -971744 / 32,  -965344 / 32,  -958688 / 32,  -951776 / 32,

  74.      -944608 / 32,  -937184 / 32,  -929504 / 32,  -921568 / 32,

  75.      -913376 / 32,  -904928 / 32,  -896224 / 32,  -887264 / 32,

  76.      -878048 / 32,  -868576 / 32,  -858848 / 32,  -848864 / 32,

  77.      -838624 / 32,  -828128 / 32,  -817376 / 32,  -806368 / 32,

  78.      -795104 / 32,  -783584 / 32,  -771808 / 32,  -759776 / 32,

  79.      -747488 / 32,  -734944 / 32,  -722144 / 32,  -709088 / 32,

  80.      -695776 / 32,  -682208 / 32,  -668384 / 32,  -654304 / 32,

  81.      -639968 / 32,  -625376 / 32,  -610528 / 32,  -595424 / 32,

  82.      -580064 / 32,  -564448 / 32,  -548576 / 32,  -532448 / 32,

  83.      -516064 / 32,  -499424 / 32,  -482528 / 32,  -465376 / 32,

  84.      -447968 / 32,  -430304 / 32,  -412384 / 32,  -394208 / 32,

  85.      -375776 / 32,  -357088 / 32,  -338144 / 32,  -318944 / 32,

  86.      -299488 / 32,  -279776 / 32,  -259808 / 32,  -239584 / 32,

  87.      -219104 / 32,  -198368 / 32,  -177376 / 32,  -156128 / 32,

  88.      -134624 / 32,  -112864 / 32,   -90848 / 32,   -68576 / 32,

  89.       -46048 / 32,   -23264 / 32,     -224 / 32,    23072 / 32,

  90.        46624 / 32,    70432 / 32,    94496 / 32,   118816 / 32,

  91.       143392 / 32,   168224 / 32,   193312 / 32,   218656 / 32,

  92.       244256 / 32,   270112 / 32,   296224 / 32,   322592 / 32,

  93.       349216 / 32,   376096 / 32,   403232 / 32,   430624 / 32,

  94.       458272 / 32,   486176 / 32,   514336 / 32,   542752 / 32,

  95.       571424 / 32,   600352 / 32,   629536 / 32,   658976 / 32,

  96.       688672 / 32,   718624 / 32,   748832 / 32,   779296 / 32,

  97.       810016 / 32,   840992 / 32,   872224 / 32,   903712 / 32,

  98.       935456 / 32,   967456 / 32,   999712 / 32,  1032224 / 32

  99. };

  100. 

  101. 

  102. /** Gain values of p(0) for long-term prediction.

  103.  *  To be indexed by the Rice coded indices.

  104.  */

  105. static const uint8_t ltp_gain_values [4][4] = {

  106.     { 0,  8, 16,  24},

  107.     {32, 40, 48,  56},

  108.     {64, 70, 76,  82},

  109.     {88, 92, 96, 100}

  110. };

  111. 

  112. 

  113. /** Inter-channel weighting factors for multi-channel correlation.

  114.  *  To be indexed by the Rice coded indices.

  115.  */

  116. static const int16_t mcc_weightings[] = {

  117.     204,  192,  179,  166,  153,  140,  128,  115,

  118.     102,   89,   76,   64,   51,   38,   25,   12,

  119.       0,  -12,  -25,  -38,  -51,  -64,  -76,  -89,

  120.    -102, -115, -128, -140, -153, -166, -179, -192

  121. };

  122. 

  123. 

  124. /** Tail codes used in arithmetic coding using block Gilbert-Moore codes.

  125.  */

  126. static const uint8_t tail_code[16][6] = {

  127.     { 74, 44, 25, 13,  7, 3},

  128.     { 68, 42, 24, 13,  7, 3},

  129.     { 58, 39, 23, 13,  7, 3},

  130.     {126, 70, 37, 19, 10, 5},

  131.     {132, 70, 37, 20, 10, 5},

  132.     {124, 70, 38, 20, 10, 5},

  133.     {120, 69, 37, 20, 11, 5},

  134.     {116, 67, 37, 20, 11, 5},

  135.     {108, 66, 36, 20, 10, 5},

  136.     {102, 62, 36, 20, 10, 5},

  137.     { 88, 58, 34, 19, 10, 5},

  138.     {162, 89, 49, 25, 13, 7},

  139.     {156, 87, 49, 26, 14, 7},

  140.     {150, 86, 47, 26, 14, 7},

  141.     {142, 84, 47, 26, 14, 7},

  142.     {131, 79, 46, 26, 14, 7}

  143. };

  144. 

  145. 

  146. enum RA_Flag {

  147.     RA_FLAG_NONE,

  148.     RA_FLAG_FRAMES,

  149.     RA_FLAG_HEADER

  150. };

  151. 

  152. 

  153. typedef struct {

  154.     uint32_t samples;         ///< number of samples, 0xFFFFFFFF if unknown

  155.     int resolution;           ///< 000 = 8-bit; 001 = 16-bit; 010 = 24-bit; 011 = 32-bit

  156.     int floating;             ///< 1 = IEEE 32-bit floating-point, 0 = integer

  157.     int frame_length;         ///< frame length for each frame (last frame may differ)

  158.     int ra_distance;          ///< distance between RA frames (in frames, 0...255)

  159.     enum RA_Flag ra_flag;     ///< indicates where the size of ra units is stored

  160.     int adapt_order;          ///< adaptive order: 1 = on, 0 = off

  161.     int coef_table;           ///< table index of Rice code parameters

  162.     int long_term_prediction; ///< long term prediction (LTP): 1 = on, 0 = off

  163.     int max_order;            ///< maximum prediction order (0..1023)

  164.     int block_switching;      ///< number of block switching levels

  165.     int bgmc;                 ///< "Block Gilbert-Moore Code": 1 = on, 0 = off (Rice coding only)

  166.     int sb_part;              ///< sub-block partition

  167.     int joint_stereo;         ///< joint stereo: 1 = on, 0 = off

  168.     int mc_coding;            ///< extended inter-channel coding (multi channel coding): 1 = on, 0 = off

  169.     int chan_config;          ///< indicates that a chan_config_info field is present

  170.     int chan_sort;            ///< channel rearrangement: 1 = on, 0 = off

  171.     int rlslms;               ///< use "Recursive Least Square-Least Mean Square" predictor: 1 = on, 0 = off

  172.     int chan_config_info;     ///< mapping of channels to loudspeaker locations. Unused until setting channel configuration is implemented.

  173.     int *chan_pos;            ///< original channel positions

  174. } ALSSpecificConfig;

  175. 

  176. 

  177. typedef struct {

  178.     int stop_flag;

  179.     int master_channel;

  180.     int time_diff_flag;

  181.     int time_diff_sign;

  182.     int time_diff_index;

  183.     int weighting[6];

  184. } ALSChannelData;

  185. 

  186. 

  187. typedef struct {

  188.     AVCodecContext *avctx;

  189.     ALSSpecificConfig sconf;

  190.     GetBitContext gb;

  191.     unsigned int cur_frame_length;  ///< length of the current frame to decode

  192.     unsigned int frame_id;          ///< the frame ID / number of the current frame

  193.     unsigned int js_switch;         ///< if true, joint-stereo decoding is enforced

  194.     unsigned int num_blocks;        ///< number of blocks used in the current frame

  195.     unsigned int s_max;             ///< maximum Rice parameter allowed in entropy coding

  196.     uint8_t *bgmc_lut;              ///< pointer at lookup tables used for BGMC

  197.     unsigned int *bgmc_lut_status;  ///< pointer at lookup table status flags used for BGMC

  198.     int ltp_lag_length;             ///< number of bits used for ltp lag value

  199.     int *use_ltp;                   ///< contains use_ltp flags for all channels

  200.     int *ltp_lag;                   ///< contains ltp lag values for all channels

  201.     int **ltp_gain;                 ///< gain values for ltp 5-tap filter for a channel

  202.     int *ltp_gain_buffer;           ///< contains all gain values for ltp 5-tap filter

  203.     int32_t **quant_cof;            ///< quantized parcor coefficients for a channel

  204.     int32_t *quant_cof_buffer;      ///< contains all quantized parcor coefficients

  205.     int32_t **lpc_cof;              ///< coefficients of the direct form prediction filter for a channel

  206.     int32_t *lpc_cof_buffer;        ///< contains all coefficients of the direct form prediction filter

  207.     int32_t *lpc_cof_reversed_buffer; ///< temporary buffer to set up a reversed versio of lpc_cof_buffer

  208.     ALSChannelData **chan_data;     ///< channel data for multi-channel correlation

  209.     ALSChannelData *chan_data_buffer; ///< contains channel data for all channels

  210.     int *reverted_channels;         ///< stores a flag for each reverted channel

  211.     int32_t *prev_raw_samples;      ///< contains unshifted raw samples from the previous block

  212.     int32_t **raw_samples;          ///< decoded raw samples for each channel

  213.     int32_t *raw_buffer;            ///< contains all decoded raw samples including carryover samples

  214. } ALSDecContext;

  215. 

  216. 

  217. typedef struct {

  218.     unsigned int block_length;      ///< number of samples within the block

  219.     unsigned int ra_block;          ///< if true, this is a random access block

  220.     int          const_block;       ///< if true, this is a constant value block

  221.     int32_t      const_val;         ///< the sample value of a constant block

  222.     int          js_blocks;         ///< true if this block contains a difference signal

  223.     unsigned int shift_lsbs;        ///< shift of values for this block

  224.     unsigned int opt_order;         ///< prediction order of this block

  225.     int          store_prev_samples;///< if true, carryover samples have to be stored

  226.     int          *use_ltp;          ///< if true, long-term prediction is used

  227.     int          *ltp_lag;          ///< lag value for long-term prediction

  228.     int          *ltp_gain;         ///< gain values for ltp 5-tap filter

  229.     int32_t      *quant_cof;        ///< quantized parcor coefficients

  230.     int32_t      *lpc_cof;          ///< coefficients of the direct form prediction

  231.     int32_t      *raw_samples;      ///< decoded raw samples / residuals for this block

  232.     int32_t      *prev_raw_samples; ///< contains unshifted raw samples from the previous block

  233.     int32_t      *raw_other;        ///< decoded raw samples of the other channel of a channel pair

  234. } ALSBlockData;

  235. 

  236. 

  237. static av_cold void dprint_specific_config(ALSDecContext *ctx)

  238. {

  239. #ifdef DEBUG

  240.     AVCodecContext *avctx    = ctx->avctx;

  241.     ALSSpecificConfig *sconf = &ctx->sconf;

  242. 

  243.     dprintf(avctx, "resolution = %i\n",           sconf->resolution);

  244.     dprintf(avctx, "floating = %i\n",             sconf->floating);

  245.     dprintf(avctx, "frame_length = %i\n",         sconf->frame_length);

  246.     dprintf(avctx, "ra_distance = %i\n",          sconf->ra_distance);

  247.     dprintf(avctx, "ra_flag = %i\n",              sconf->ra_flag);

  248.     dprintf(avctx, "adapt_order = %i\n",          sconf->adapt_order);

  249.     dprintf(avctx, "coef_table = %i\n",           sconf->coef_table);

  250.     dprintf(avctx, "long_term_prediction = %i\n", sconf->long_term_prediction);

  251.     dprintf(avctx, "max_order = %i\n",            sconf->max_order);

  252.     dprintf(avctx, "block_switching = %i\n",      sconf->block_switching);

  253.     dprintf(avctx, "bgmc = %i\n",                 sconf->bgmc);

  254.     dprintf(avctx, "sb_part = %i\n",              sconf->sb_part);

  255.     dprintf(avctx, "joint_stereo = %i\n",         sconf->joint_stereo);

  256.     dprintf(avctx, "mc_coding = %i\n",            sconf->mc_coding);

  257.     dprintf(avctx, "chan_config = %i\n",          sconf->chan_config);

  258.     dprintf(avctx, "chan_sort = %i\n",            sconf->chan_sort);

  259.     dprintf(avctx, "RLSLMS = %i\n",               sconf->rlslms);

  260.     dprintf(avctx, "chan_config_info = %i\n",     sconf->chan_config_info);

  261. #endif

  262. }

  263. 

  264. 

  265. /** Reads an ALSSpecificConfig from a buffer into the output struct.

  266.  */

  267. static av_cold int read_specific_config(ALSDecContext *ctx)

  268. {

  269.     GetBitContext gb;

  270.     uint64_t ht_size;

  271.     int i, config_offset, crc_enabled;

  272.     MPEG4AudioConfig m4ac;

  273.     ALSSpecificConfig *sconf = &ctx->sconf;

  274.     AVCodecContext *avctx    = ctx->avctx;

  275.     uint32_t als_id, header_size, trailer_size;

  276. 

  277.     init_get_bits(&gb, avctx->extradata, avctx->extradata_size * 8);

  278. 

  279.     config_offset = ff_mpeg4audio_get_config(&m4ac, avctx->extradata,

  280.                                              avctx->extradata_size);

  281. 

  282.     if (config_offset < 0)

  283.         return -1;

  284. 

  285.     skip_bits_long(&gb, config_offset);

  286. 

  287.     if (get_bits_left(&gb) < (30 << 3))

  288.         return -1;

  289. 

  290.     // read the fixed items

  291.     als_id                      = get_bits_long(&gb, 32);

  292.     avctx->sample_rate          = m4ac.sample_rate;

  293.     skip_bits_long(&gb, 32); // sample rate already known

  294.     sconf->samples              = get_bits_long(&gb, 32);

  295.     avctx->channels             = m4ac.channels;

  296.     skip_bits(&gb, 16);      // number of channels already knwon

  297.     skip_bits(&gb, 3);       // skip file_type

  298.     sconf->resolution           = get_bits(&gb, 3);

  299.     sconf->floating             = get_bits1(&gb);

  300.     skip_bits1(&gb);         // skip msb_first

  301.     sconf->frame_length         = get_bits(&gb, 16) + 1;

  302.     sconf->ra_distance          = get_bits(&gb, 8);

  303.     sconf->ra_flag              = get_bits(&gb, 2);

  304.     sconf->adapt_order          = get_bits1(&gb);

  305.     sconf->coef_table           = get_bits(&gb, 2);

  306.     sconf->long_term_prediction = get_bits1(&gb);

  307.     sconf->max_order            = get_bits(&gb, 10);

  308.     sconf->block_switching      = get_bits(&gb, 2);

  309.     sconf->bgmc                 = get_bits1(&gb);

  310.     sconf->sb_part              = get_bits1(&gb);

  311.     sconf->joint_stereo         = get_bits1(&gb);

  312.     sconf->mc_coding            = get_bits1(&gb);

  313.     sconf->chan_config          = get_bits1(&gb);

  314.     sconf->chan_sort            = get_bits1(&gb);

  315.     crc_enabled                 = get_bits1(&gb);

  316.     sconf->rlslms               = get_bits1(&gb);

  317.     skip_bits(&gb, 5);       // skip 5 reserved bits

  318.     skip_bits1(&gb);         // skip aux_data_enabled

  319. 

  320. 

  321.     // check for ALSSpecificConfig struct

  322.     if (als_id != MKBETAG('A','L','S','\0'))

  323.         return -1;

  324. 

  325.     ctx->cur_frame_length = sconf->frame_length;

  326. 

  327.     // read channel config

  328.     if (sconf->chan_config)

  329.         sconf->chan_config_info = get_bits(&gb, 16);

  330.     // TODO: use this to set avctx->channel_layout

  331. 

  332. 

  333.     // read channel sorting

  334.     if (sconf->chan_sort && avctx->channels > 1) {

  335.         int chan_pos_bits = av_ceil_log2(avctx->channels);

  336.         int bits_needed  = avctx->channels * chan_pos_bits + 7;

  337.         if (get_bits_left(&gb) < bits_needed)

  338.             return -1;

  339. 

  340.         if (!(sconf->chan_pos = av_malloc(avctx->channels * sizeof(*sconf->chan_pos))))

  341.             return AVERROR(ENOMEM);

  342. 

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

  344.             sconf->chan_pos[i] = get_bits(&gb, chan_pos_bits);

  345. 

  346.         align_get_bits(&gb);

  347.         // TODO: use this to actually do channel sorting

  348.     } else {

  349.         sconf->chan_sort = 0;

  350.     }

  351. 

  352. 

  353.     // read fixed header and trailer sizes,

  354.     // if size = 0xFFFFFFFF then there is no data field!

  355.     if (get_bits_left(&gb) < 64)

  356.         return -1;

  357. 

  358.     header_size  = get_bits_long(&gb, 32);

  359.     trailer_size = get_bits_long(&gb, 32);

  360.     if (header_size  == 0xFFFFFFFF)

  361.         header_size  = 0;

  362.     if (trailer_size == 0xFFFFFFFF)

  363.         trailer_size = 0;

  364. 

  365.     ht_size = ((int64_t)(header_size) + (int64_t)(trailer_size)) << 3;

  366. 

  367. 

  368.     // skip the header and trailer data

  369.     if (get_bits_left(&gb) < ht_size)

  370.         return -1;

  371. 

  372.     if (ht_size > INT32_MAX)

  373.         return -1;

  374. 

  375.     skip_bits_long(&gb, ht_size);

  376. 

  377. 

  378.     // skip the crc data

  379.     if (crc_enabled) {

  380.         if (get_bits_left(&gb) < 32)

  381.             return -1;

  382. 

  383.         skip_bits_long(&gb, 32);

  384.     }

  385. 

  386. 

  387.     // no need to read the rest of ALSSpecificConfig (ra_unit_size & aux data)

  388. 

  389.     dprint_specific_config(ctx);

  390. 

  391.     return 0;

  392. }

  393. 

  394. 

  395. /** Checks the ALSSpecificConfig for unsupported features.

  396.  */

  397. static int check_specific_config(ALSDecContext *ctx)

  398. {

  399.     ALSSpecificConfig *sconf = &ctx->sconf;

  400.     int error = 0;

  401. 

  402.     // report unsupported feature and set error value

  403.     #define MISSING_ERR(cond, str, errval)              \

  404.     {                                                   \

  405.         if (cond) {                                     \

  406.             av_log_missing_feature(ctx->avctx, str, 0); \

  407.             error = errval;                             \

  408.         }                                               \

  409.     }

  410. 

  411.     MISSING_ERR(sconf->floating,             "Floating point decoding",     -1);

  412.     MISSING_ERR(sconf->rlslms,               "Adaptive RLS-LMS prediction", -1);

  413.     MISSING_ERR(sconf->chan_sort,            "Channel sorting",              0);

  414. 

  415.     return error;

  416. }

  417. 

  418. 

  419. /** Parses the bs_info field to extract the block partitioning used in

  420.  *  block switching mode, refer to ISO/IEC 14496-3, section 11.6.2.

  421.  */

  422. static void parse_bs_info(const uint32_t bs_info, unsigned int n,

  423.                           unsigned int div, unsigned int **div_blocks,

  424.                           unsigned int *num_blocks)

  425. {

  426.     if (n < 31 && ((bs_info << n) & 0x40000000)) {

  427.         // if the level is valid and the investigated bit n is set

  428.         // then recursively check both children at bits (2n+1) and (2n+2)

  429.         n   *= 2;

  430.         div += 1;

  431.         parse_bs_info(bs_info, n + 1, div, div_blocks, num_blocks);

  432.         parse_bs_info(bs_info, n + 2, div, div_blocks, num_blocks);

  433.     } else {

  434.         // else the bit is not set or the last level has been reached

  435.         // (bit implicitly not set)

  436.         **div_blocks = div;

  437.         (*div_blocks)++;

  438.         (*num_blocks)++;

  439.     }

  440. }

  441. 

  442. 

  443. /** Reads and decodes a Rice codeword.

  444.  */

  445. static int32_t decode_rice(GetBitContext *gb, unsigned int k)

  446. {

  447.     int max = get_bits_left(gb) - k;

  448.     int q   = get_unary(gb, 0, max);

  449.     int r   = k ? get_bits1(gb) : !(q & 1);

  450. 

  451.     if (k > 1) {

  452.         q <<= (k - 1);

  453.         q  += get_bits_long(gb, k - 1);

  454.     } else if (!k) {

  455.         q >>= 1;

  456.     }

  457.     return r ? q : ~q;

  458. }

  459. 

  460. 

  461. /** Converts PARCOR coefficient k to direct filter coefficient.

  462.  */

  463. static void parcor_to_lpc(unsigned int k, const int32_t *par, int32_t *cof)

  464. {

  465.     int i, j;

  466. 

  467.     for (i = 0, j = k - 1; i < j; i++, j--) {

  468.         int tmp1 = ((MUL64(par[k], cof[j]) + (1 << 19)) >> 20);

  469.         cof[j]  += ((MUL64(par[k], cof[i]) + (1 << 19)) >> 20);

  470.         cof[i]  += tmp1;

  471.     }

  472.     if (i == j)

  473.         cof[i] += ((MUL64(par[k], cof[j]) + (1 << 19)) >> 20);

  474. 

  475.     cof[k] = par[k];

  476. }

  477. 

  478. 

  479. /** Reads block switching field if necessary and sets actual block sizes.

  480.  *  Also assures that the block sizes of the last frame correspond to the

  481.  *  actual number of samples.

  482.  */

  483. static void get_block_sizes(ALSDecContext *ctx, unsigned int *div_blocks,

  484.                             uint32_t *bs_info)

  485. {

  486.     ALSSpecificConfig *sconf     = &ctx->sconf;

  487.     GetBitContext *gb            = &ctx->gb;

  488.     unsigned int *ptr_div_blocks = div_blocks;

  489.     unsigned int b;

  490. 

  491.     if (sconf->block_switching) {

  492.         unsigned int bs_info_len = 1 << (sconf->block_switching + 2);

  493.         *bs_info = get_bits_long(gb, bs_info_len);

  494.         *bs_info <<= (32 - bs_info_len);

  495.     }

  496. 

  497.     ctx->num_blocks = 0;

  498.     parse_bs_info(*bs_info, 0, 0, &ptr_div_blocks, &ctx->num_blocks);

  499. 

  500.     // The last frame may have an overdetermined block structure given in

  501.     // the bitstream. In that case the defined block structure would need

  502.     // more samples than available to be consistent.

  503.     // The block structure is actually used but the block sizes are adapted

  504.     // to fit the actual number of available samples.

  505.     // Example: 5 samples, 2nd level block sizes: 2 2 2 2.

  506.     // This results in the actual block sizes:    2 2 1 0.

  507.     // This is not specified in 14496-3 but actually done by the reference

  508.     // codec RM22 revision 2.

  509.     // This appears to happen in case of an odd number of samples in the last

  510.     // frame which is actually not allowed by the block length switching part

  511.     // of 14496-3.

  512.     // The ALS conformance files feature an odd number of samples in the last

  513.     // frame.

  514. 

  515.     for (b = 0; b < ctx->num_blocks; b++)

  516.         div_blocks[b] = ctx->sconf.frame_length >> div_blocks[b];

  517. 

  518.     if (ctx->cur_frame_length != ctx->sconf.frame_length) {

  519.         unsigned int remaining = ctx->cur_frame_length;

  520. 

  521.         for (b = 0; b < ctx->num_blocks; b++) {

  522.             if (remaining <= div_blocks[b]) {

  523.                 div_blocks[b] = remaining;

  524.                 ctx->num_blocks = b + 1;

  525.                 break;

  526.             }

  527. 

  528.             remaining -= div_blocks[b];

  529.         }

  530.     }

  531. }

  532. 

  533. 

  534. /** Reads the block data for a constant block

  535.  */

  536. static void read_const_block_data(ALSDecContext *ctx, ALSBlockData *bd)

  537. {

  538.     ALSSpecificConfig *sconf = &ctx->sconf;

  539.     AVCodecContext *avctx    = ctx->avctx;

  540.     GetBitContext *gb        = &ctx->gb;

  541. 

  542.     bd->const_val    = 0;

  543.     bd->const_block  = get_bits1(gb);    // 1 = constant value, 0 = zero block (silence)

  544.     bd->js_blocks    = get_bits1(gb);

  545. 

  546.     // skip 5 reserved bits

  547.     skip_bits(gb, 5);

  548. 

  549.     if (bd->const_block) {

  550.         unsigned int const_val_bits = sconf->floating ? 24 : avctx->bits_per_raw_sample;

  551.         bd->const_val = get_sbits_long(gb, const_val_bits);

  552.     }

  553. 

  554.     // ensure constant block decoding by reusing this field

  555.     bd->const_block = 1;

  556. }

  557. 

  558. 

  559. /** Decodes the block data for a constant block

  560.  */

  561. static void decode_const_block_data(ALSDecContext *ctx, ALSBlockData *bd)

  562. {

  563.     int      smp = bd->block_length;

  564.     int32_t  val = bd->const_val;

  565.     int32_t *dst = bd->raw_samples;

  566. 

  567.     // write raw samples into buffer

  568.     for (; smp; smp--)

  569.         *dst++ = val;

  570. }

  571. 

  572. 

  573. /** Reads the block data for a non-constant block

  574.  */

  575. static int read_var_block_data(ALSDecContext *ctx, ALSBlockData *bd)

  576. {

  577.     ALSSpecificConfig *sconf = &ctx->sconf;

  578.     AVCodecContext *avctx    = ctx->avctx;

  579.     GetBitContext *gb        = &ctx->gb;

  580.     unsigned int k;

  581.     unsigned int s[8];

  582.     unsigned int sx[8];

  583.     unsigned int sub_blocks, log2_sub_blocks, sb_length;

  584.     unsigned int start      = 0;

  585.     unsigned int opt_order;

  586.     int          sb;

  587.     int32_t      *quant_cof = bd->quant_cof;

  588.     int32_t      *current_res;

  589. 

  590. 

  591.     // ensure variable block decoding by reusing this field

  592.     bd->const_block = 0;

  593. 

  594.     bd->opt_order   = 1;

  595.     bd->js_blocks   = get_bits1(gb);

  596. 

  597.     opt_order       = bd->opt_order;

  598. 

  599.     // determine the number of subblocks for entropy decoding

  600.     if (!sconf->bgmc && !sconf->sb_part) {

  601.         log2_sub_blocks = 0;

  602.     } else {

  603.         if (sconf->bgmc && sconf->sb_part)

  604.             log2_sub_blocks = get_bits(gb, 2);

  605.         else

  606.             log2_sub_blocks = 2 * get_bits1(gb);

  607.     }

  608. 

  609.     sub_blocks = 1 << log2_sub_blocks;

  610. 

  611.     // do not continue in case of a damaged stream since

  612.     // block_length must be evenly divisible by sub_blocks

  613.     if (bd->block_length & (sub_blocks - 1)) {

  614.         av_log(avctx, AV_LOG_WARNING,

  615.                "Block length is not evenly divisible by the number of subblocks.\n");

  616.         return -1;

  617.     }

  618. 

  619.     sb_length = bd->block_length >> log2_sub_blocks;

  620. 

  621.     if (sconf->bgmc) {

  622.         s[0] = get_bits(gb, 8 + (sconf->resolution > 1));

  623.         for (k = 1; k < sub_blocks; k++)

  624.             s[k] = s[k - 1] + decode_rice(gb, 2);

  625. 

  626.         for (k = 0; k < sub_blocks; k++) {

  627.             sx[k]   = s[k] & 0x0F;

  628.             s [k] >>= 4;

  629.         }

  630.     } else {

  631.         s[0] = get_bits(gb, 4 + (sconf->resolution > 1));

  632.         for (k = 1; k < sub_blocks; k++)

  633.             s[k] = s[k - 1] + decode_rice(gb, 0);

  634.     }

  635. 

  636.     if (get_bits1(gb))

  637.         bd->shift_lsbs = get_bits(gb, 4) + 1;

  638. 

  639.     bd->store_prev_samples = (bd->js_blocks && bd->raw_other) || bd->shift_lsbs;

  640. 

  641. 

  642.     if (!sconf->rlslms) {

  643.         if (sconf->adapt_order) {

  644.             int opt_order_length = av_ceil_log2(av_clip((bd->block_length >> 3) - 1,

  645.                                                 2, sconf->max_order + 1));

  646.             bd->opt_order        = get_bits(gb, opt_order_length);

  647.         } else {

  648.             bd->opt_order = sconf->max_order;

  649.         }

  650. 

  651.         opt_order = bd->opt_order;

  652. 

  653.         if (opt_order) {

  654.             int add_base;

  655. 

  656.             if (sconf->coef_table == 3) {

  657.                 add_base = 0x7F;

  658. 

  659.                 // read coefficient 0

  660.                 quant_cof[0] = 32 * parcor_scaled_values[get_bits(gb, 7)];

  661. 

  662.                 // read coefficient 1

  663.                 if (opt_order > 1)

  664.                     quant_cof[1] = -32 * parcor_scaled_values[get_bits(gb, 7)];

  665. 

  666.                 // read coefficients 2 to opt_order

  667.                 for (k = 2; k < opt_order; k++)

  668.                     quant_cof[k] = get_bits(gb, 7);

  669.             } else {

  670.                 int k_max;

  671.                 add_base = 1;

  672. 

  673.                 // read coefficient 0 to 19

  674.                 k_max = FFMIN(opt_order, 20);

  675.                 for (k = 0; k < k_max; k++) {

  676.                     int rice_param = parcor_rice_table[sconf->coef_table][k][1];

  677.                     int offset     = parcor_rice_table[sconf->coef_table][k][0];

  678.                     quant_cof[k] = decode_rice(gb, rice_param) + offset;

  679.                 }

  680. 

  681.                 // read coefficients 20 to 126

  682.                 k_max = FFMIN(opt_order, 127);

  683.                 for (; k < k_max; k++)

  684.                     quant_cof[k] = decode_rice(gb, 2) + (k & 1);

  685. 

  686.                 // read coefficients 127 to opt_order

  687.                 for (; k < opt_order; k++)

  688.                     quant_cof[k] = decode_rice(gb, 1);

  689. 

  690.                 quant_cof[0] = 32 * parcor_scaled_values[quant_cof[0] + 64];

  691. 

  692.                 if (opt_order > 1)

  693.                     quant_cof[1] = -32 * parcor_scaled_values[quant_cof[1] + 64];

  694.             }

  695. 

  696.             for (k = 2; k < opt_order; k++)

  697.                 quant_cof[k] = (quant_cof[k] << 14) + (add_base << 13);

  698.         }

  699.     }

  700. 

  701.     // read LTP gain and lag values

  702.     if (sconf->long_term_prediction) {

  703.         *bd->use_ltp = get_bits1(gb);

  704. 

  705.         if (*bd->use_ltp) {

  706.             int r, c;

  707. 

  708.             bd->ltp_gain[0]   = decode_rice(gb, 1) << 3;

  709.             bd->ltp_gain[1]   = decode_rice(gb, 2) << 3;

  710. 

  711.             r                 = get_unary(gb, 0, 4);

  712.             c                 = get_bits(gb, 2);

  713.             bd->ltp_gain[2]   = ltp_gain_values[r][c];

  714. 

  715.             bd->ltp_gain[3]   = decode_rice(gb, 2) << 3;

  716.             bd->ltp_gain[4]   = decode_rice(gb, 1) << 3;

  717. 

  718.             *bd->ltp_lag      = get_bits(gb, ctx->ltp_lag_length);

  719.             *bd->ltp_lag     += FFMAX(4, opt_order + 1);

  720.         }

  721.     }

  722. 

  723.     // read first value and residuals in case of a random access block

  724.     if (bd->ra_block) {

  725.         if (opt_order)

  726.             bd->raw_samples[0] = decode_rice(gb, avctx->bits_per_raw_sample - 4);

  727.         if (opt_order > 1)

  728.             bd->raw_samples[1] = decode_rice(gb, FFMIN(s[0] + 3, ctx->s_max));

  729.         if (opt_order > 2)

  730.             bd->raw_samples[2] = decode_rice(gb, FFMIN(s[0] + 1, ctx->s_max));

  731. 

  732.         start = FFMIN(opt_order, 3);

  733.     }

  734. 

  735.     // read all residuals

  736.     if (sconf->bgmc) {

  737.         unsigned int delta[sub_blocks];

  738.         unsigned int k    [sub_blocks];

  739.         unsigned int b = av_clip((av_ceil_log2(bd->block_length) - 3) >> 1, 0, 5);

  740.         unsigned int i = start;

  741. 

  742.         // read most significant bits

  743.         unsigned int high;

  744.         unsigned int low;

  745.         unsigned int value;

  746. 

  747.         ff_bgmc_decode_init(gb, &high, &low, &value);

  748. 

  749.         current_res = bd->raw_samples + start;

  750. 

  751.         for (sb = 0; sb < sub_blocks; sb++, i = 0) {

  752.             k    [sb] = s[sb] > b ? s[sb] - b : 0;

  753.             delta[sb] = 5 - s[sb] + k[sb];

  754. 

  755.             ff_bgmc_decode(gb, sb_length, current_res,

  756.                         delta[sb], sx[sb], &high, &low, &value, ctx->bgmc_lut, ctx->bgmc_lut_status);

  757. 

  758.             current_res += sb_length;

  759.         }

  760. 

  761.         ff_bgmc_decode_end(gb);

  762. 

  763. 

  764.         // read least significant bits and tails

  765.         i = start;

  766.         current_res = bd->raw_samples + start;

  767. 

  768.         for (sb = 0; sb < sub_blocks; sb++, i = 0) {

  769.             unsigned int cur_tail_code = tail_code[sx[sb]][delta[sb]];

  770.             unsigned int cur_k         = k[sb];

  771.             unsigned int cur_s         = s[sb];

  772. 

  773.             for (; i < sb_length; i++) {

  774.                 int32_t res = *current_res;

  775. 

  776.                 if (res == cur_tail_code) {

  777.                     unsigned int max_msb =   (2 + (sx[sb] > 2) + (sx[sb] > 10))

  778.                                           << (5 - delta[sb]);

  779. 

  780.                     res = decode_rice(gb, cur_s);

  781. 

  782.                     if (res >= 0) {

  783.                         res += (max_msb    ) << cur_k;

  784.                     } else {

  785.                         res -= (max_msb - 1) << cur_k;

  786.                     }

  787.                 } else {

  788.                     if (res > cur_tail_code)

  789.                         res--;

  790. 

  791.                     if (res & 1)

  792.                         res = -res;

  793. 

  794.                     res >>= 1;

  795. 

  796.                     if (cur_k) {

  797.                         res <<= cur_k;

  798.                         res  |= get_bits_long(gb, cur_k);

  799.                     }

  800.                 }

  801. 

  802.                 *current_res++ = res;

  803.             }

  804.         }

  805.     } else {

  806.         current_res = bd->raw_samples + start;

  807. 

  808.         for (sb = 0; sb < sub_blocks; sb++, start = 0)

  809.             for (; start < sb_length; start++)

  810.                 *current_res++ = decode_rice(gb, s[sb]);

  811.      }

  812. 

  813.     if (!sconf->mc_coding || ctx->js_switch)

  814.         align_get_bits(gb);

  815. 

  816.     return 0;

  817. }

  818. 

  819. 

  820. /** Decodes the block data for a non-constant block

  821.  */

  822. static int decode_var_block_data(ALSDecContext *ctx, ALSBlockData *bd)

  823. {

  824.     ALSSpecificConfig *sconf = &ctx->sconf;

  825.     unsigned int block_length = bd->block_length;

  826.     unsigned int smp = 0;

  827.     unsigned int k;

  828.     int opt_order             = bd->opt_order;

  829.     int sb;

  830.     int64_t y;

  831.     int32_t *quant_cof        = bd->quant_cof;

  832.     int32_t *lpc_cof          = bd->lpc_cof;

  833.     int32_t *raw_samples      = bd->raw_samples;

  834.     int32_t *raw_samples_end  = bd->raw_samples + bd->block_length;

  835.     int32_t *lpc_cof_reversed = ctx->lpc_cof_reversed_buffer;

  836. 

  837.     // reverse long-term prediction

  838.     if (*bd->use_ltp) {

  839.         int ltp_smp;

  840. 

  841.         for (ltp_smp = FFMAX(*bd->ltp_lag - 2, 0); ltp_smp < block_length; ltp_smp++) {

  842.             int center = ltp_smp - *bd->ltp_lag;

  843.             int begin  = FFMAX(0, center - 2);

  844.             int end    = center + 3;

  845.             int tab    = 5 - (end - begin);

  846.             int base;

  847. 

  848.             y = 1 << 6;

  849. 

  850.             for (base = begin; base < end; base++, tab++)

  851.                 y += MUL64(bd->ltp_gain[tab], raw_samples[base]);

  852. 

  853.             raw_samples[ltp_smp] += y >> 7;

  854.         }

  855.     }

  856. 

  857.     // reconstruct all samples from residuals

  858.     if (bd->ra_block) {

  859.         for (smp = 0; smp < opt_order; smp++) {

  860.             y = 1 << 19;

  861. 

  862.             for (sb = 0; sb < smp; sb++)

  863.                 y += MUL64(lpc_cof[sb], raw_samples[-(sb + 1)]);

  864. 

  865.             *raw_samples++ -= y >> 20;

  866.             parcor_to_lpc(smp, quant_cof, lpc_cof);

  867.         }

  868.     } else {

  869.         for (k = 0; k < opt_order; k++)

  870.             parcor_to_lpc(k, quant_cof, lpc_cof);

  871. 

  872.         // store previous samples in case that they have to be altered

  873.         if (bd->store_prev_samples)

  874.             memcpy(bd->prev_raw_samples, raw_samples - sconf->max_order,

  875.                    sizeof(*bd->prev_raw_samples) * sconf->max_order);

  876. 

  877.         // reconstruct difference signal for prediction (joint-stereo)

  878.         if (bd->js_blocks && bd->raw_other) {

  879.             int32_t *left, *right;

  880. 

  881.             if (bd->raw_other > raw_samples) {  // D = R - L

  882.                 left  = raw_samples;

  883.                 right = bd->raw_other;

  884.             } else {                                // D = R - L

  885.                 left  = bd->raw_other;

  886.                 right = raw_samples;

  887.             }

  888. 

  889.             for (sb = -1; sb >= -sconf->max_order; sb--)

  890.                 raw_samples[sb] = right[sb] - left[sb];

  891.         }

  892. 

  893.         // reconstruct shifted signal

  894.         if (bd->shift_lsbs)

  895.             for (sb = -1; sb >= -sconf->max_order; sb--)

  896.                 raw_samples[sb] >>= bd->shift_lsbs;

  897.     }

  898. 

  899.     // reverse linear prediction coefficients for efficiency

  900.     lpc_cof = lpc_cof + opt_order;

  901. 

  902.     for (sb = 0; sb < opt_order; sb++)

  903.         lpc_cof_reversed[sb] = lpc_cof[-(sb + 1)];

  904. 

  905.     // reconstruct raw samples

  906.     raw_samples = bd->raw_samples + smp;

  907.     lpc_cof     = lpc_cof_reversed + opt_order;

  908. 

  909.     for (; raw_samples < raw_samples_end; raw_samples++) {

  910.         y = 1 << 19;

  911. 

  912.         for (sb = -opt_order; sb < 0; sb++)

  913.             y += MUL64(lpc_cof[sb], raw_samples[sb]);

  914. 

  915.         *raw_samples -= y >> 20;

  916.     }

  917. 

  918.     raw_samples = bd->raw_samples;

  919. 

  920.     // restore previous samples in case that they have been altered

  921.     if (bd->store_prev_samples)

  922.         memcpy(raw_samples - sconf->max_order, bd->prev_raw_samples,

  923.                sizeof(*raw_samples) * sconf->max_order);

  924. 

  925.     return 0;

  926. }

  927. 

  928. 

  929. /** Reads the block data.

  930.  */

  931. static int read_block(ALSDecContext *ctx, ALSBlockData *bd)

  932. {

  933.     GetBitContext *gb        = &ctx->gb;

  934. 

  935.     // read block type flag and read the samples accordingly

  936.     if (get_bits1(gb)) {

  937.         if (read_var_block_data(ctx, bd))

  938.             return -1;

  939.     } else {

  940.         read_const_block_data(ctx, bd);

  941.     }

  942. 

  943.     return 0;

  944. }

  945. 

  946. 

  947. /** Decodes the block data.

  948.  */

  949. static int decode_block(ALSDecContext *ctx, ALSBlockData *bd)

  950. {

  951.     unsigned int smp;

  952. 

  953.     // read block type flag and read the samples accordingly

  954.     if (bd->const_block)

  955.         decode_const_block_data(ctx, bd);

  956.     else if (decode_var_block_data(ctx, bd))

  957.         return -1;

  958. 

  959.     // TODO: read RLSLMS extension data

  960. 

  961.     if (bd->shift_lsbs)

  962.         for (smp = 0; smp < bd->block_length; smp++)

  963.             bd->raw_samples[smp] <<= bd->shift_lsbs;

  964. 

  965.     return 0;

  966. }

  967. 

  968. 

  969. /** Reads and decodes block data successively.

  970.  */

  971. static int read_decode_block(ALSDecContext *ctx, ALSBlockData *bd)

  972. {

  973.     int ret;

  974. 

  975.     ret = read_block(ctx, bd);

  976. 

  977.     if (ret)

  978.         return ret;

  979. 

  980.     ret = decode_block(ctx, bd);

  981. 

  982.     return ret;

  983. }

  984. 

  985. 

  986. /** Computes the number of samples left to decode for the current frame and

  987.  *  sets these samples to zero.

  988.  */

  989. static void zero_remaining(unsigned int b, unsigned int b_max,

  990.                            const unsigned int *div_blocks, int32_t *buf)

  991. {

  992.     unsigned int count = 0;

  993. 

  994.     while (b < b_max)

  995.         count += div_blocks[b];

  996. 

  997.     if (count)

  998.         memset(buf, 0, sizeof(*buf) * count);

  999. }

  1000. 

  1001. 

  1002. /** Decodes blocks independently.

  1003.  */

  1004. static int decode_blocks_ind(ALSDecContext *ctx, unsigned int ra_frame,

  1005.                              unsigned int c, const unsigned int *div_blocks,

  1006.                              unsigned int *js_blocks)

  1007. {

  1008.     unsigned int b;

  1009.     ALSBlockData bd;

  1010. 

  1011.     memset(&bd, 0, sizeof(ALSBlockData));

  1012. 

  1013.     bd.ra_block         = ra_frame;

  1014.     bd.use_ltp          = ctx->use_ltp;

  1015.     bd.ltp_lag          = ctx->ltp_lag;

  1016.     bd.ltp_gain         = ctx->ltp_gain[0];

  1017.     bd.quant_cof        = ctx->quant_cof[0];

  1018.     bd.lpc_cof          = ctx->lpc_cof[0];

  1019.     bd.prev_raw_samples = ctx->prev_raw_samples;

  1020.     bd.raw_samples      = ctx->raw_samples[c];

  1021. 

  1022. 

  1023.     for (b = 0; b < ctx->num_blocks; b++) {

  1024.         bd.shift_lsbs       = 0;

  1025.         bd.block_length     = div_blocks[b];

  1026. 

  1027.         if (read_decode_block(ctx, &bd)) {

  1028.             // damaged block, write zero for the rest of the frame

  1029.             zero_remaining(b, ctx->num_blocks, div_blocks, bd.raw_samples);

  1030.             return -1;

  1031.         }

  1032.         bd.raw_samples += div_blocks[b];

  1033.         bd.ra_block     = 0;

  1034.     }

  1035. 

  1036.     return 0;

  1037. }

  1038. 

  1039. 

  1040. /** Decodes blocks dependently.

  1041.  */

  1042. static int decode_blocks(ALSDecContext *ctx, unsigned int ra_frame,

  1043.                          unsigned int c, const unsigned int *div_blocks,

  1044.                          unsigned int *js_blocks)

  1045. {

  1046.     ALSSpecificConfig *sconf = &ctx->sconf;

  1047.     unsigned int offset = 0;

  1048.     unsigned int b;

  1049.     ALSBlockData bd[2];

  1050. 

  1051.     memset(bd, 0, 2 * sizeof(ALSBlockData));

  1052. 

  1053.     bd[0].ra_block         = ra_frame;

  1054.     bd[0].use_ltp          = ctx->use_ltp;

  1055.     bd[0].ltp_lag          = ctx->ltp_lag;

  1056.     bd[0].ltp_gain         = ctx->ltp_gain[0];

  1057.     bd[0].quant_cof        = ctx->quant_cof[0];

  1058.     bd[0].lpc_cof          = ctx->lpc_cof[0];

  1059.     bd[0].prev_raw_samples = ctx->prev_raw_samples;

  1060.     bd[0].js_blocks        = *js_blocks;

  1061. 

  1062.     bd[1].ra_block         = ra_frame;

  1063.     bd[1].use_ltp          = ctx->use_ltp;

  1064.     bd[1].ltp_lag          = ctx->ltp_lag;

  1065.     bd[1].ltp_gain         = ctx->ltp_gain[0];

  1066.     bd[1].quant_cof        = ctx->quant_cof[0];

  1067.     bd[1].lpc_cof          = ctx->lpc_cof[0];

  1068.     bd[1].prev_raw_samples = ctx->prev_raw_samples;

  1069.     bd[1].js_blocks        = *(js_blocks + 1);

  1070. 

  1071.     // decode all blocks

  1072.     for (b = 0; b < ctx->num_blocks; b++) {

  1073.         unsigned int s;

  1074. 

  1075.         bd[0].shift_lsbs   = 0;

  1076.         bd[1].shift_lsbs   = 0;

  1077. 

  1078.         bd[0].block_length = div_blocks[b];

  1079.         bd[1].block_length = div_blocks[b];

  1080. 

  1081.         bd[0].raw_samples  = ctx->raw_samples[c    ] + offset;

  1082.         bd[1].raw_samples  = ctx->raw_samples[c + 1] + offset;

  1083. 

  1084.         bd[0].raw_other    = bd[1].raw_samples;

  1085.         bd[1].raw_other    = bd[0].raw_samples;

  1086. 

  1087.         if(read_decode_block(ctx, &bd[0]) || read_decode_block(ctx, &bd[1])) {

  1088.             // damaged block, write zero for the rest of the frame

  1089.             zero_remaining(b, ctx->num_blocks, div_blocks, bd[0].raw_samples);

  1090.             zero_remaining(b, ctx->num_blocks, div_blocks, bd[1].raw_samples);

  1091.             return -1;

  1092.         }

  1093. 

  1094.         // reconstruct joint-stereo blocks

  1095.         if (bd[0].js_blocks) {

  1096.             if (bd[1].js_blocks)

  1097.                 av_log(ctx->avctx, AV_LOG_WARNING, "Invalid channel pair!\n");

  1098. 

  1099.             for (s = 0; s < div_blocks[b]; s++)

  1100.                 bd[0].raw_samples[s] = bd[1].raw_samples[s] - bd[0].raw_samples[s];

  1101.         } else if (bd[1].js_blocks) {

  1102.             for (s = 0; s < div_blocks[b]; s++)

  1103.                 bd[1].raw_samples[s] = bd[1].raw_samples[s] + bd[0].raw_samples[s];

  1104.         }

  1105. 

  1106.         offset  += div_blocks[b];

  1107.         bd[0].ra_block = 0;

  1108.         bd[1].ra_block = 0;

  1109.     }

  1110. 

  1111.     // store carryover raw samples,

  1112.     // the others channel raw samples are stored by the calling function.

  1113.     memmove(ctx->raw_samples[c] - sconf->max_order,

  1114.             ctx->raw_samples[c] - sconf->max_order + sconf->frame_length,

  1115.             sizeof(*ctx->raw_samples[c]) * sconf->max_order);

  1116. 

  1117.     return 0;

  1118. }

  1119. 

  1120. 

  1121. /** Reads the channel data.

  1122.   */

  1123. static int read_channel_data(ALSDecContext *ctx, ALSChannelData *cd, int c)

  1124. {

  1125.     GetBitContext *gb       = &ctx->gb;

  1126.     ALSChannelData *current = cd;

  1127.     unsigned int channels   = ctx->avctx->channels;

  1128.     int entries             = 0;

  1129. 

  1130.     while (entries < channels && !(current->stop_flag = get_bits1(gb))) {

  1131.         current->master_channel = get_bits_long(gb, av_ceil_log2(channels));

  1132. 

  1133.         if (current->master_channel >= channels) {

  1134.             av_log(ctx->avctx, AV_LOG_ERROR, "Invalid master channel!\n");

  1135.             return -1;

  1136.         }

  1137. 

  1138.         if (current->master_channel != c) {

  1139.             current->time_diff_flag = get_bits1(gb);

  1140.             current->weighting[0]   = mcc_weightings[av_clip(decode_rice(gb, 1) + 16, 0, 32)];

  1141.             current->weighting[1]   = mcc_weightings[av_clip(decode_rice(gb, 2) + 14, 0, 32)];

  1142.             current->weighting[2]   = mcc_weightings[av_clip(decode_rice(gb, 1) + 16, 0, 32)];

  1143. 

  1144.             if (current->time_diff_flag) {

  1145.                 current->weighting[3] = mcc_weightings[av_clip(decode_rice(gb, 1) + 16, 0, 32)];

  1146.                 current->weighting[4] = mcc_weightings[av_clip(decode_rice(gb, 1) + 16, 0, 32)];

  1147.                 current->weighting[5] = mcc_weightings[av_clip(decode_rice(gb, 1) + 16, 0, 32)];

  1148. 

  1149.                 current->time_diff_sign  = get_bits1(gb);

  1150.                 current->time_diff_index = get_bits(gb, ctx->ltp_lag_length - 3) + 3;

  1151.             }

  1152.         }

  1153. 

  1154.         current++;

  1155.         entries++;

  1156.     }

  1157. 

  1158.     if (entries == channels) {

  1159.         av_log(ctx->avctx, AV_LOG_ERROR, "Damaged channel data!\n");

  1160.         return -1;

  1161.     }

  1162. 

  1163.     align_get_bits(gb);

  1164.     return 0;

  1165. }

  1166. 

  1167. 

  1168. /** Recursively reverts the inter-channel correlation for a block.

  1169.  */

  1170. static int revert_channel_correlation(ALSDecContext *ctx, ALSBlockData *bd,

  1171.                                        ALSChannelData **cd, int *reverted,

  1172.                                        unsigned int offset, int c)

  1173. {

  1174.     ALSChannelData *ch = cd[c];

  1175.     unsigned int   dep = 0;

  1176.     unsigned int channels = ctx->avctx->channels;

  1177. 

  1178.     if (reverted[c])

  1179.         return 0;

  1180. 

  1181.     reverted[c] = 1;

  1182. 

  1183.     while (dep < channels && !ch[dep].stop_flag) {

  1184.         revert_channel_correlation(ctx, bd, cd, reverted, offset,

  1185.                                    ch[dep].master_channel);

  1186. 

  1187.         dep++;

  1188.     }

  1189. 

  1190.     if (dep == channels) {

  1191.         av_log(ctx->avctx, AV_LOG_WARNING, "Invalid channel correlation!\n");

  1192.         return -1;

  1193.     }

  1194. 

  1195.     bd->use_ltp     = ctx->use_ltp + c;

  1196.     bd->ltp_lag     = ctx->ltp_lag + c;

  1197.     bd->ltp_gain    = ctx->ltp_gain[c];

  1198.     bd->lpc_cof     = ctx->lpc_cof[c];

  1199.     bd->quant_cof   = ctx->quant_cof[c];

  1200.     bd->raw_samples = ctx->raw_samples[c] + offset;

  1201. 

  1202.     dep = 0;

  1203.     while (!ch[dep].stop_flag) {

  1204.         unsigned int smp;

  1205.         unsigned int begin = 1;

  1206.         unsigned int end   = bd->block_length - 1;

  1207.         int64_t y;

  1208.         int32_t *master = ctx->raw_samples[ch[dep].master_channel] + offset;

  1209. 

  1210.         if (ch[dep].time_diff_flag) {

  1211.             int t = ch[dep].time_diff_index;

  1212. 

  1213.             if (ch[dep].time_diff_sign) {

  1214.                 t      = -t;

  1215.                 begin -= t;

  1216.             } else {

  1217.                 end   -= t;

  1218.             }

  1219. 

  1220.             for (smp = begin; smp < end; smp++) {

  1221.                 y  = (1 << 6) +

  1222.                      MUL64(ch[dep].weighting[0], master[smp - 1    ]) +

  1223.                      MUL64(ch[dep].weighting[1], master[smp        ]) +

  1224.                      MUL64(ch[dep].weighting[2], master[smp + 1    ]) +

  1225.                      MUL64(ch[dep].weighting[3], master[smp - 1 + t]) +

  1226.                      MUL64(ch[dep].weighting[4], master[smp     + t]) +

  1227.                      MUL64(ch[dep].weighting[5], master[smp + 1 + t]);

  1228. 

  1229.                 bd->raw_samples[smp] += y >> 7;

  1230.             }

  1231.         } else {

  1232.             for (smp = begin; smp < end; smp++) {

  1233.                 y  = (1 << 6) +

  1234.                      MUL64(ch[dep].weighting[0], master[smp - 1]) +

  1235.                      MUL64(ch[dep].weighting[1], master[smp    ]) +

  1236.                      MUL64(ch[dep].weighting[2], master[smp + 1]);

  1237. 

  1238.                 bd->raw_samples[smp] += y >> 7;

  1239.             }

  1240.         }

  1241. 

  1242.         dep++;

  1243.     }

  1244. 

  1245.     return 0;

  1246. }

  1247. 

  1248. 

  1249. /** Reads the frame data.

  1250.  */

  1251. static int read_frame_data(ALSDecContext *ctx, unsigned int ra_frame)

  1252. {

  1253.     ALSSpecificConfig *sconf = &ctx->sconf;

  1254.     AVCodecContext *avctx    = ctx->avctx;

  1255.     GetBitContext *gb = &ctx->gb;

  1256.     unsigned int div_blocks[32];                ///< block sizes.

  1257.     unsigned int c;

  1258.     unsigned int js_blocks[2];

  1259. 

  1260.     uint32_t bs_info = 0;

  1261. 

  1262.     // skip the size of the ra unit if present in the frame

  1263.     if (sconf->ra_flag == RA_FLAG_FRAMES && ra_frame)

  1264.         skip_bits_long(gb, 32);

  1265. 

  1266.     if (sconf->mc_coding && sconf->joint_stereo) {

  1267.         ctx->js_switch = get_bits1(gb);

  1268.         align_get_bits(gb);

  1269.     }

  1270. 

  1271.     if (!sconf->mc_coding || ctx->js_switch) {

  1272.         int independent_bs = !sconf->joint_stereo;

  1273. 

  1274.         for (c = 0; c < avctx->channels; c++) {

  1275.             js_blocks[0] = 0;

  1276.             js_blocks[1] = 0;

  1277. 

  1278.             get_block_sizes(ctx, div_blocks, &bs_info);

  1279. 

  1280.             // if joint_stereo and block_switching is set, independent decoding

  1281.             // is signaled via the first bit of bs_info

  1282.             if (sconf->joint_stereo && sconf->block_switching)

  1283.                 if (bs_info >> 31)

  1284.                     independent_bs = 2;

  1285. 

  1286.             // if this is the last channel, it has to be decoded independently

  1287.             if (c == avctx->channels - 1)

  1288.                 independent_bs = 1;

  1289. 

  1290.             if (independent_bs) {

  1291.                 if (decode_blocks_ind(ctx, ra_frame, c, div_blocks, js_blocks))

  1292.                     return -1;

  1293. 

  1294.                 independent_bs--;

  1295.             } else {

  1296.                 if (decode_blocks(ctx, ra_frame, c, div_blocks, js_blocks))

  1297.                     return -1;

  1298. 

  1299.                 c++;

  1300.             }

  1301. 

  1302.             // store carryover raw samples

  1303.             memmove(ctx->raw_samples[c] - sconf->max_order,

  1304.                     ctx->raw_samples[c] - sconf->max_order + sconf->frame_length,

  1305.                     sizeof(*ctx->raw_samples[c]) * sconf->max_order);

  1306.         }

  1307.     } else { // multi-channel coding

  1308.         ALSBlockData   bd;

  1309.         int            b;

  1310.         int            *reverted_channels = ctx->reverted_channels;

  1311.         unsigned int   offset             = 0;

  1312. 

  1313.         for (c = 0; c < avctx->channels; c++)

  1314.             if (ctx->chan_data[c] < ctx->chan_data_buffer) {

  1315.                 av_log(ctx->avctx, AV_LOG_ERROR, "Invalid channel data!\n");

  1316.                 return -1;

  1317.             }

  1318. 

  1319.         memset(&bd,               0, sizeof(ALSBlockData));

  1320.         memset(reverted_channels, 0, sizeof(*reverted_channels) * avctx->channels);

  1321. 

  1322.         bd.ra_block         = ra_frame;

  1323.         bd.prev_raw_samples = ctx->prev_raw_samples;

  1324. 

  1325.         get_block_sizes(ctx, div_blocks, &bs_info);

  1326. 

  1327.         for (b = 0; b < ctx->num_blocks; b++) {

  1328.             bd.shift_lsbs   = 0;

  1329.             bd.block_length = div_blocks[b];

  1330. 

  1331.             for (c = 0; c < avctx->channels; c++) {

  1332.                 bd.use_ltp     = ctx->use_ltp + c;

  1333.                 bd.ltp_lag     = ctx->ltp_lag + c;

  1334.                 bd.ltp_gain    = ctx->ltp_gain[c];

  1335.                 bd.lpc_cof     = ctx->lpc_cof[c];

  1336.                 bd.quant_cof   = ctx->quant_cof[c];

  1337.                 bd.raw_samples = ctx->raw_samples[c] + offset;

  1338.                 bd.raw_other   = NULL;

  1339. 

  1340.                 read_block(ctx, &bd);

  1341.                 if (read_channel_data(ctx, ctx->chan_data[c], c))

  1342.                     return -1;

  1343.             }

  1344. 

  1345.             for (c = 0; c < avctx->channels; c++)

  1346.                 if (revert_channel_correlation(ctx, &bd, ctx->chan_data,

  1347.                                                reverted_channels, offset, c))

  1348.                     return -1;

  1349. 

  1350.             for (c = 0; c < avctx->channels; c++) {

  1351.                 bd.use_ltp     = ctx->use_ltp + c;

  1352.                 bd.ltp_lag     = ctx->ltp_lag + c;

  1353.                 bd.ltp_gain    = ctx->ltp_gain[c];

  1354.                 bd.lpc_cof     = ctx->lpc_cof[c];

  1355.                 bd.quant_cof   = ctx->quant_cof[c];

  1356.                 bd.raw_samples = ctx->raw_samples[c] + offset;

  1357.                 decode_block(ctx, &bd);

  1358.             }

  1359. 

  1360.             memset(reverted_channels, 0, avctx->channels * sizeof(*reverted_channels));

  1361.             offset      += div_blocks[b];

  1362.             bd.ra_block  = 0;

  1363.         }

  1364. 

  1365.         // store carryover raw samples

  1366.         for (c = 0; c < avctx->channels; c++)

  1367.             memmove(ctx->raw_samples[c] - sconf->max_order,

  1368.                     ctx->raw_samples[c] - sconf->max_order + sconf->frame_length,

  1369.                     sizeof(*ctx->raw_samples[c]) * sconf->max_order);

  1370.     }

  1371. 

  1372.     // TODO: read_diff_float_data

  1373. 

  1374.     return 0;

  1375. }

  1376. 

  1377. 

  1378. /** Decodes an ALS frame.

  1379.  */

  1380. static int decode_frame(AVCodecContext *avctx,

  1381.                         void *data, int *data_size,

  1382.                         AVPacket *avpkt)

  1383. {

  1384.     ALSDecContext *ctx       = avctx->priv_data;

  1385.     ALSSpecificConfig *sconf = &ctx->sconf;

  1386.     const uint8_t *buffer    = avpkt->data;

  1387.     int buffer_size          = avpkt->size;

  1388.     int invalid_frame, size;

  1389.     unsigned int c, sample, ra_frame, bytes_read, shift;

  1390. 

  1391.     init_get_bits(&ctx->gb, buffer, buffer_size * 8);

  1392. 

  1393.     // In the case that the distance between random access frames is set to zero

  1394.     // (sconf->ra_distance == 0) no frame is treated as a random access frame.

  1395.     // For the first frame, if prediction is used, all samples used from the

  1396.     // previous frame are assumed to be zero.

  1397.     ra_frame = sconf->ra_distance && !(ctx->frame_id % sconf->ra_distance);

  1398. 

  1399.     // the last frame to decode might have a different length

  1400.     if (sconf->samples != 0xFFFFFFFF)

  1401.         ctx->cur_frame_length = FFMIN(sconf->samples - ctx->frame_id * (uint64_t) sconf->frame_length,

  1402.                                       sconf->frame_length);

  1403.     else

  1404.         ctx->cur_frame_length = sconf->frame_length;

  1405. 

  1406.     // decode the frame data

  1407.     if ((invalid_frame = read_frame_data(ctx, ra_frame) < 0))

  1408.         av_log(ctx->avctx, AV_LOG_WARNING,

  1409.                "Reading frame data failed. Skipping RA unit.\n");

  1410. 

  1411.     ctx->frame_id++;

  1412. 

  1413.     // check for size of decoded data

  1414.     size = ctx->cur_frame_length * avctx->channels *

  1415.            (av_get_bits_per_sample_format(avctx->sample_fmt) >> 3);

  1416. 

  1417.     if (size > *data_size) {

  1418.         av_log(avctx, AV_LOG_ERROR, "Decoded data exceeds buffer size.\n");

  1419.         return -1;

  1420.     }

  1421. 

  1422.     *data_size = size;

  1423. 

  1424.     // transform decoded frame into output format

  1425.     #define INTERLEAVE_OUTPUT(bps)                                 \

  1426.     {                                                              \

  1427.         int##bps##_t *dest = (int##bps##_t*) data;                 \

  1428.         shift = bps - ctx->avctx->bits_per_raw_sample;             \

  1429.         for (sample = 0; sample < ctx->cur_frame_length; sample++) \

  1430.             for (c = 0; c < avctx->channels; c++)                  \

  1431.                 *dest++ = ctx->raw_samples[c][sample] << shift;    \

  1432.     }

  1433. 

  1434.     if (ctx->avctx->bits_per_raw_sample <= 16) {

  1435.         INTERLEAVE_OUTPUT(16)

  1436.     } else {

  1437.         INTERLEAVE_OUTPUT(32)

  1438.     }

  1439. 

  1440.     bytes_read = invalid_frame ? buffer_size :

  1441.                                  (get_bits_count(&ctx->gb) + 7) >> 3;

  1442. 

  1443.     return bytes_read;

  1444. }

  1445. 

  1446. 

  1447. /** Uninitializes the ALS decoder.

  1448.  */

  1449. static av_cold int decode_end(AVCodecContext *avctx)

  1450. {

  1451.     ALSDecContext *ctx = avctx->priv_data;

  1452. 

  1453.     av_freep(&ctx->sconf.chan_pos);

  1454. 

  1455.     ff_bgmc_end(&ctx->bgmc_lut, &ctx->bgmc_lut_status);

  1456. 

  1457.     av_freep(&ctx->use_ltp);

  1458.     av_freep(&ctx->ltp_lag);

  1459.     av_freep(&ctx->ltp_gain);

  1460.     av_freep(&ctx->ltp_gain_buffer);

  1461.     av_freep(&ctx->quant_cof);

  1462.     av_freep(&ctx->lpc_cof);

  1463.     av_freep(&ctx->quant_cof_buffer);

  1464.     av_freep(&ctx->lpc_cof_buffer);

  1465.     av_freep(&ctx->lpc_cof_reversed_buffer);

  1466.     av_freep(&ctx->prev_raw_samples);

  1467.     av_freep(&ctx->raw_samples);

  1468.     av_freep(&ctx->raw_buffer);

  1469.     av_freep(&ctx->chan_data);

  1470.     av_freep(&ctx->chan_data_buffer);

  1471.     av_freep(&ctx->reverted_channels);

  1472. 

  1473.     return 0;

  1474. }

  1475. 

  1476. 

  1477. /** Initializes the ALS decoder.

  1478.  */

  1479. static av_cold int decode_init(AVCodecContext *avctx)

  1480. {

  1481.     unsigned int c;

  1482.     unsigned int channel_size;

  1483.     int num_buffers;

  1484.     ALSDecContext *ctx = avctx->priv_data;

  1485.     ALSSpecificConfig *sconf = &ctx->sconf;

  1486.     ctx->avctx = avctx;

  1487. 

  1488.     if (!avctx->extradata) {

  1489.         av_log(avctx, AV_LOG_ERROR, "Missing required ALS extradata.\n");

  1490.         return -1;

  1491.     }

  1492. 

  1493.     if (read_specific_config(ctx)) {

  1494.         av_log(avctx, AV_LOG_ERROR, "Reading ALSSpecificConfig failed.\n");

  1495.         decode_end(avctx);

  1496.         return -1;

  1497.     }

  1498. 

  1499.     if (check_specific_config(ctx)) {

  1500.         decode_end(avctx);

  1501.         return -1;

  1502.     }

  1503. 

  1504.     if (sconf->bgmc)

  1505.         ff_bgmc_init(avctx, &ctx->bgmc_lut, &ctx->bgmc_lut_status);

  1506. 

  1507.     if (sconf->floating) {

  1508.         avctx->sample_fmt          = SAMPLE_FMT_FLT;

  1509.         avctx->bits_per_raw_sample = 32;

  1510.     } else {

  1511.         avctx->sample_fmt          = sconf->resolution > 1

  1512.                                      ? SAMPLE_FMT_S32 : SAMPLE_FMT_S16;

  1513.         avctx->bits_per_raw_sample = (sconf->resolution + 1) * 8;

  1514.     }

  1515. 

  1516.     // set maximum Rice parameter for progressive decoding based on resolution

  1517.     // This is not specified in 14496-3 but actually done by the reference

  1518.     // codec RM22 revision 2.

  1519.     ctx->s_max = sconf->resolution > 1 ? 31 : 15;

  1520. 

  1521.     // set lag value for long-term prediction

  1522.     ctx->ltp_lag_length = 8 + (avctx->sample_rate >=  96000) +

  1523.                               (avctx->sample_rate >= 192000);

  1524. 

  1525.     // allocate quantized parcor coefficient buffer

  1526.     num_buffers = sconf->mc_coding ? avctx->channels : 1;

  1527. 

  1528.     ctx->quant_cof        = av_malloc(sizeof(*ctx->quant_cof) * num_buffers);

  1529.     ctx->lpc_cof          = av_malloc(sizeof(*ctx->lpc_cof)   * num_buffers);

  1530.     ctx->quant_cof_buffer = av_malloc(sizeof(*ctx->quant_cof_buffer) *

  1531.                                       num_buffers * sconf->max_order);

  1532.     ctx->lpc_cof_buffer   = av_malloc(sizeof(*ctx->lpc_cof_buffer) *

  1533.                                       num_buffers * sconf->max_order);

  1534.     ctx->lpc_cof_reversed_buffer = av_malloc(sizeof(*ctx->lpc_cof_buffer) *

  1535.                                              sconf->max_order);

  1536. 

  1537.     if (!ctx->quant_cof              || !ctx->lpc_cof        ||

  1538.         !ctx->quant_cof_buffer       || !ctx->lpc_cof_buffer ||

  1539.         !ctx->lpc_cof_reversed_buffer) {

  1540.         av_log(avctx, AV_LOG_ERROR, "Allocating buffer memory failed.\n");

  1541.         return AVERROR(ENOMEM);

  1542.     }

  1543. 

  1544.     // assign quantized parcor coefficient buffers

  1545.     for (c = 0; c < num_buffers; c++) {

  1546.         ctx->quant_cof[c] = ctx->quant_cof_buffer + c * sconf->max_order;

  1547.         ctx->lpc_cof[c]   = ctx->lpc_cof_buffer   + c * sconf->max_order;

  1548.     }

  1549. 

  1550.     // allocate and assign lag and gain data buffer for ltp mode

  1551.     ctx->use_ltp         = av_mallocz(sizeof(*ctx->use_ltp)  * num_buffers);

  1552.     ctx->ltp_lag         = av_malloc (sizeof(*ctx->ltp_lag)  * num_buffers);

  1553.     ctx->ltp_gain        = av_malloc (sizeof(*ctx->ltp_gain) * num_buffers);

  1554.     ctx->ltp_gain_buffer = av_malloc (sizeof(*ctx->ltp_gain_buffer) *

  1555.                                       num_buffers * 5);

  1556. 

  1557.     if (!ctx->use_ltp  || !ctx->ltp_lag ||

  1558.         !ctx->ltp_gain || !ctx->ltp_gain_buffer) {

  1559.         av_log(avctx, AV_LOG_ERROR, "Allocating buffer memory failed.\n");

  1560.         decode_end(avctx);

  1561.         return AVERROR(ENOMEM);

  1562.     }

  1563. 

  1564.     for (c = 0; c < num_buffers; c++)

  1565.         ctx->ltp_gain[c] = ctx->ltp_gain_buffer + c * 5;

  1566. 

  1567.     // allocate and assign channel data buffer for mcc mode

  1568.     if (sconf->mc_coding) {

  1569.         ctx->chan_data_buffer  = av_malloc(sizeof(*ctx->chan_data_buffer) *

  1570.                                            num_buffers * num_buffers);

  1571.         ctx->chan_data         = av_malloc(sizeof(*ctx->chan_data) *

  1572.                                            num_buffers);

  1573.         ctx->reverted_channels = av_malloc(sizeof(*ctx->reverted_channels) *

  1574.                                            num_buffers);

  1575. 

  1576.         if (!ctx->chan_data_buffer || !ctx->chan_data || !ctx->reverted_channels) {

  1577.             av_log(avctx, AV_LOG_ERROR, "Allocating buffer memory failed.\n");

  1578.             decode_end(avctx);

  1579.             return AVERROR(ENOMEM);

  1580.         }

  1581. 

  1582.         for (c = 0; c < num_buffers; c++)

  1583.             ctx->chan_data[c] = ctx->chan_data_buffer + c * num_buffers;

  1584.     } else {

  1585.         ctx->chan_data         = NULL;

  1586.         ctx->chan_data_buffer  = NULL;

  1587.         ctx->reverted_channels = NULL;

  1588.     }

  1589. 

  1590.     avctx->frame_size = sconf->frame_length;

  1591.     channel_size      = sconf->frame_length + sconf->max_order;

  1592. 

  1593.     ctx->prev_raw_samples = av_malloc (sizeof(*ctx->prev_raw_samples) * sconf->max_order);

  1594.     ctx->raw_buffer       = av_mallocz(sizeof(*ctx->     raw_buffer)  * avctx->channels * channel_size);

  1595.     ctx->raw_samples      = av_malloc (sizeof(*ctx->     raw_samples) * avctx->channels);

  1596. 

  1597.     // allocate previous raw sample buffer

  1598.     if (!ctx->prev_raw_samples || !ctx->raw_buffer|| !ctx->raw_samples) {

  1599.         av_log(avctx, AV_LOG_ERROR, "Allocating buffer memory failed.\n");

  1600.         decode_end(avctx);

  1601.         return AVERROR(ENOMEM);

  1602.     }

  1603. 

  1604.     // assign raw samples buffers

  1605.     ctx->raw_samples[0] = ctx->raw_buffer + sconf->max_order;

  1606.     for (c = 1; c < avctx->channels; c++)

  1607.         ctx->raw_samples[c] = ctx->raw_samples[c - 1] + channel_size;

  1608. 

  1609.     return 0;

  1610. }

  1611. 

  1612. 

  1613. /** Flushes (resets) the frame ID after seeking.

  1614.  */

  1615. static av_cold void flush(AVCodecContext *avctx)

  1616. {

  1617.     ALSDecContext *ctx = avctx->priv_data;

  1618. 

  1619.     ctx->frame_id = 0;

  1620. }

  1621. 

  1622. 

  1623. AVCodec als_decoder = {

  1624.     "als",

  1625.     CODEC_TYPE_AUDIO,

  1626.     CODEC_ID_MP4ALS,

  1627.     sizeof(ALSDecContext),

  1628.     decode_init,

  1629.     NULL,

  1630.     decode_end,

  1631.     decode_frame,

  1632.     .flush = flush,

  1633.     .capabilities = CODEC_CAP_SUBFRAMES,

  1634.     .long_name = NULL_IF_CONFIG_SMALL("MPEG-4 Audio Lossless Coding (ALS)"),

  1635. };