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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. 

  38. #include <stdint.h>

  39. 

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

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

  42.  *  by the encoder and stored in ALSSpecificConfig.

  43.  */

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

  45.     { {-52, 4}, {-29, 5}, {-31, 4}, { 19, 4}, {-16, 4},

  46.       { 12, 3}, { -7, 3}, {  9, 3}, { -5, 3}, {  6, 3},

  47.       { -4, 3}, {  3, 3}, { -3, 2}, {  3, 2}, { -2, 2},

  48.       {  3, 2}, { -1, 2}, {  2, 2}, { -1, 2}, {  2, 2} },

  49.     { {-58, 3}, {-42, 4}, {-46, 4}, { 37, 5}, {-36, 4},

  50.       { 29, 4}, {-29, 4}, { 25, 4}, {-23, 4}, { 20, 4},

  51.       {-17, 4}, { 16, 4}, {-12, 4}, { 12, 3}, {-10, 4},

  52.       {  7, 3}, { -4, 4}, {  3, 3}, { -1, 3}, {  1, 3} },

  53.     { {-59, 3}, {-45, 5}, {-50, 4}, { 38, 4}, {-39, 4},

  54.       { 32, 4}, {-30, 4}, { 25, 3}, {-23, 3}, { 20, 3},

  55.       {-20, 3}, { 16, 3}, {-13, 3}, { 10, 3}, { -7, 3},

  56.       {  3, 3}, {  0, 3}, { -1, 3}, {  2, 3}, { -1, 2} }

  57. };

  58. 

  59. 

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

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

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

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

  64.  */

  65. static const int16_t parcor_scaled_values[] = {

  66.     -1048544 / 32, -1048288 / 32, -1047776 / 32, -1047008 / 32,

  67.     -1045984 / 32, -1044704 / 32, -1043168 / 32, -1041376 / 32,

  68.     -1039328 / 32, -1037024 / 32, -1034464 / 32, -1031648 / 32,

  69.     -1028576 / 32, -1025248 / 32, -1021664 / 32, -1017824 / 32,

  70.     -1013728 / 32, -1009376 / 32, -1004768 / 32,  -999904 / 32,

  71.      -994784 / 32,  -989408 / 32,  -983776 / 32,  -977888 / 32,

  72.      -971744 / 32,  -965344 / 32,  -958688 / 32,  -951776 / 32,

  73.      -944608 / 32,  -937184 / 32,  -929504 / 32,  -921568 / 32,

  74.      -913376 / 32,  -904928 / 32,  -896224 / 32,  -887264 / 32,

  75.      -878048 / 32,  -868576 / 32,  -858848 / 32,  -848864 / 32,

  76.      -838624 / 32,  -828128 / 32,  -817376 / 32,  -806368 / 32,

  77.      -795104 / 32,  -783584 / 32,  -771808 / 32,  -759776 / 32,

  78.      -747488 / 32,  -734944 / 32,  -722144 / 32,  -709088 / 32,

  79.      -695776 / 32,  -682208 / 32,  -668384 / 32,  -654304 / 32,

  80.      -639968 / 32,  -625376 / 32,  -610528 / 32,  -595424 / 32,

  81.      -580064 / 32,  -564448 / 32,  -548576 / 32,  -532448 / 32,

  82.      -516064 / 32,  -499424 / 32,  -482528 / 32,  -465376 / 32,

  83.      -447968 / 32,  -430304 / 32,  -412384 / 32,  -394208 / 32,

  84.      -375776 / 32,  -357088 / 32,  -338144 / 32,  -318944 / 32,

  85.      -299488 / 32,  -279776 / 32,  -259808 / 32,  -239584 / 32,

  86.      -219104 / 32,  -198368 / 32,  -177376 / 32,  -156128 / 32,

  87.      -134624 / 32,  -112864 / 32,   -90848 / 32,   -68576 / 32,

  88.       -46048 / 32,   -23264 / 32,     -224 / 32,    23072 / 32,

  89.        46624 / 32,    70432 / 32,    94496 / 32,   118816 / 32,

  90.       143392 / 32,   168224 / 32,   193312 / 32,   218656 / 32,

  91.       244256 / 32,   270112 / 32,   296224 / 32,   322592 / 32,

  92.       349216 / 32,   376096 / 32,   403232 / 32,   430624 / 32,

  93.       458272 / 32,   486176 / 32,   514336 / 32,   542752 / 32,

  94.       571424 / 32,   600352 / 32,   629536 / 32,   658976 / 32,

  95.       688672 / 32,   718624 / 32,   748832 / 32,   779296 / 32,

  96.       810016 / 32,   840992 / 32,   872224 / 32,   903712 / 32,

  97.       935456 / 32,   967456 / 32,   999712 / 32,  1032224 / 32

  98. };

  99. 

  100. 

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

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

  103.  */

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

  105.     { 0,  8, 16,  24},

  106.     {32, 40, 48,  56},

  107.     {64, 70, 76,  82},

  108.     {88, 92, 96, 100}

  109. };

  110. 

  111. 

  112. enum RA_Flag {

  113.     RA_FLAG_NONE,

  114.     RA_FLAG_FRAMES,

  115.     RA_FLAG_HEADER

  116. };

  117. 

  118. 

  119. typedef struct {

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  140.     uint32_t header_size;     ///< header size of original audio file in bytes, provided for debugging

  141.     uint32_t trailer_size;    ///< trailer size of original audio file in bytes, provided for debugging

  142. } ALSSpecificConfig;

  143. 

  144. 

  145. typedef struct {

  146.     AVCodecContext *avctx;

  147.     ALSSpecificConfig sconf;

  148.     GetBitContext gb;

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

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

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

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

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

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

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

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

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

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

  159. } ALSDecContext;

  160. 

  161. 

  162. static av_cold void dprint_specific_config(ALSDecContext *ctx)

  163. {

  164. #ifdef DEBUG

  165.     AVCodecContext *avctx    = ctx->avctx;

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

  167. 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  188. #endif

  189. }

  190. 

  191. 

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

  193.  */

  194. static av_cold int read_specific_config(ALSDecContext *ctx)

  195. {

  196.     GetBitContext gb;

  197.     uint64_t ht_size;

  198.     int i, config_offset, crc_enabled;

  199.     MPEG4AudioConfig m4ac;

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

  201.     AVCodecContext *avctx    = ctx->avctx;

  202.     uint32_t als_id;

  203. 

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

  205. 

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

  207.                                              avctx->extradata_size);

  208. 

  209.     if (config_offset < 0)

  210.         return -1;

  211. 

  212.     skip_bits_long(&gb, config_offset);

  213. 

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

  215.         return -1;

  216. 

  217.     // read the fixed items

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

  219.     avctx->sample_rate          = m4ac.sample_rate;

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

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

  222.     avctx->channels             = m4ac.channels;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  242.     crc_enabled                 = get_bits1(&gb);

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

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

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

  246. 

  247. 

  248.     // check for ALSSpecificConfig struct

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

  250.         return -1;

  251. 

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

  253. 

  254.     // allocate quantized parcor coefficient buffer

  255.     if (!(ctx->quant_cof = av_malloc(sizeof(*ctx->quant_cof) * sconf->max_order)) ||

  256.         !(ctx->lpc_cof   = av_malloc(sizeof(*ctx->lpc_cof)   * sconf->max_order))) {

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

  258.         return AVERROR(ENOMEM);

  259.     }

  260. 

  261.     // read channel config

  262.     if (sconf->chan_config)

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

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

  265. 

  266. 

  267.     // read channel sorting

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

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

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

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

  272.             return -1;

  273. 

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

  275.             return AVERROR(ENOMEM);

  276. 

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

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

  279. 

  280.         align_get_bits(&gb);

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

  282.     } else {

  283.         sconf->chan_sort = 0;

  284.     }

  285. 

  286. 

  287.     // read fixed header and trailer sizes,

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

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

  290.         return -1;

  291. 

  292.     sconf->header_size  = get_bits_long(&gb, 32);

  293.     sconf->trailer_size = get_bits_long(&gb, 32);

  294.     if (sconf->header_size  == 0xFFFFFFFF)

  295.         sconf->header_size  = 0;

  296.     if (sconf->trailer_size == 0xFFFFFFFF)

  297.         sconf->trailer_size = 0;

  298. 

  299.     ht_size = ((int64_t)(sconf->header_size) + (int64_t)(sconf->trailer_size)) << 3;

  300. 

  301. 

  302.     // skip the header and trailer data

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

  304.         return -1;

  305. 

  306.     if (ht_size > INT32_MAX)

  307.         return -1;

  308. 

  309.     skip_bits_long(&gb, ht_size);

  310. 

  311. 

  312.     // skip the crc data

  313.     if (crc_enabled) {

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

  315.             return -1;

  316. 

  317.         skip_bits_long(&gb, 32);

  318.     }

  319. 

  320. 

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

  322. 

  323.     dprint_specific_config(ctx);

  324. 

  325.     return 0;

  326. }

  327. 

  328. 

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

  330.  */

  331. static int check_specific_config(ALSDecContext *ctx)

  332. {

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

  334.     int error = 0;

  335. 

  336.     // report unsupported feature and set error value

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

  338.     {                                                   \

  339.         if (cond) {                                     \

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

  341.             error = errval;                             \

  342.         }                                               \

  343.     }

  344. 

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

  346.     MISSING_ERR(sconf->bgmc,                 "BGMC entropy decoding",       -1);

  347.     MISSING_ERR(sconf->mc_coding,            "Multi-channel correlation",   -1);

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

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

  350. 

  351.     return error;

  352. }

  353. 

  354. 

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

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

  357.  */

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

  359.                           unsigned int div, unsigned int **div_blocks,

  360.                           unsigned int *num_blocks)

  361. {

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

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

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

  365.         n   *= 2;

  366.         div += 1;

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

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

  369.     } else {

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

  371.         // (bit implicitly not set)

  372.         **div_blocks = div;

  373.         (*div_blocks)++;

  374.         (*num_blocks)++;

  375.     }

  376. }

  377. 

  378. 

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

  380.  */

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

  382. {

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

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

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

  386. 

  387.     if (k > 1) {

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

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

  390.     } else if (!k) {

  391.         q >>= 1;

  392.     }

  393.     return r ? q : ~q;

  394. }

  395. 

  396. 

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

  398.  */

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

  400. {

  401.     int i, j;

  402. 

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

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

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

  406.         cof[i]  += tmp1;

  407.     }

  408.     if (i == j)

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

  410. 

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

  412. }

  413. 

  414. 

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

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

  417.  *  actual number of samples.

  418.  */

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

  420.                             uint32_t *bs_info)

  421. {

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

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

  424.     unsigned int *ptr_div_blocks = div_blocks;

  425.     unsigned int b;

  426. 

  427.     if (sconf->block_switching) {

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

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

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

  431.     }

  432. 

  433.     ctx->num_blocks = 0;

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

  435. 

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

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

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

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

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

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

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

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

  444.     // codec RM22 revision 2.

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

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

  447.     // of 14496-3.

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

  449.     // frame.

  450. 

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

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

  453. 

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

  455.         unsigned int remaining = ctx->cur_frame_length;

  456. 

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

  458.             if (remaining < div_blocks[b]) {

  459.                 div_blocks[b] = remaining;

  460.                 ctx->num_blocks = b + 1;

  461.                 break;

  462.             }

  463. 

  464.             remaining -= div_blocks[b];

  465.         }

  466.     }

  467. }

  468. 

  469. 

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

  471.  */

  472. static void read_const_block(ALSDecContext *ctx, int32_t *raw_samples,

  473.                              unsigned int block_length, unsigned int *js_blocks)

  474. {

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

  476.     AVCodecContext *avctx    = ctx->avctx;

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

  478.     int32_t const_val        = 0;

  479.     unsigned int const_block, k;

  480. 

  481.     const_block  = get_bits1(gb);    // 1 = constant value, 0 = zero block (silence)

  482.     *js_blocks   = get_bits1(gb);

  483. 

  484.     // skip 5 reserved bits

  485.     skip_bits(gb, 5);

  486. 

  487.     if (const_block) {

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

  489.         const_val = get_sbits_long(gb, const_val_bits);

  490.     }

  491. 

  492.     // write raw samples into buffer

  493.     for (k = 0; k < block_length; k++)

  494.         raw_samples[k] = const_val;

  495. }

  496. 

  497. 

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

  499.  */

  500. static int read_var_block(ALSDecContext *ctx, unsigned int ra_block,

  501.                           int32_t *raw_samples, unsigned int block_length,

  502.                           unsigned int *js_blocks, int32_t *raw_other,

  503.                           unsigned int *shift_lsbs)

  504. {

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

  506.     AVCodecContext *avctx    = ctx->avctx;

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

  508.     unsigned int k;

  509.     unsigned int s[8];

  510.     unsigned int sub_blocks, log2_sub_blocks, sb_length;

  511.     unsigned int opt_order  = 1;

  512.     int32_t      *quant_cof = ctx->quant_cof;

  513.     int32_t      *lpc_cof   = ctx->lpc_cof;

  514.     unsigned int start      = 0;

  515.     int          smp        = 0;

  516.     int          sb, store_prev_samples;

  517.     int64_t      y;

  518.     int          use_ltp    = 0;

  519.     int          ltp_lag    = 0;

  520.     int          ltp_gain[5];

  521. 

  522.     *js_blocks  = get_bits1(gb);

  523. 

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

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

  526.         log2_sub_blocks = 0;

  527.     } else {

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

  529.             log2_sub_blocks = get_bits(gb, 2);

  530.         else

  531.             log2_sub_blocks = 2 * get_bits1(gb);

  532.     }

  533. 

  534.     sub_blocks = 1 << log2_sub_blocks;

  535. 

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

  537.     // block_length must be evenly divisible by sub_blocks

  538.     if (block_length & (sub_blocks - 1)) {

  539.         av_log(avctx, AV_LOG_WARNING,

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

  541.         return -1;

  542.     }

  543. 

  544.     sb_length = block_length >> log2_sub_blocks;

  545. 

  546. 

  547.     if (sconf->bgmc) {

  548.         // TODO: BGMC mode

  549.     } else {

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

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

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

  553.     }

  554. 

  555.     if (get_bits1(gb))

  556.         *shift_lsbs = get_bits(gb, 4) + 1;

  557. 

  558.     store_prev_samples = (*js_blocks && raw_other) || *shift_lsbs;

  559. 

  560. 

  561.     if (!sconf->rlslms) {

  562.         if (sconf->adapt_order) {

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

  564.                                                 2, sconf->max_order + 1));

  565.             opt_order            = get_bits(gb, opt_order_length);

  566.         } else {

  567.             opt_order = sconf->max_order;

  568.         }

  569. 

  570.         if (opt_order) {

  571.             int add_base;

  572. 

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

  574.                 add_base = 0x7F;

  575. 

  576.                 // read coefficient 0

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

  578. 

  579.                 // read coefficient 1

  580.                 if (opt_order > 1)

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

  582. 

  583.                 // read coefficients 2 to opt_order

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

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

  586.             } else {

  587.                 int k_max;

  588.                 add_base = 1;

  589. 

  590.                 // read coefficient 0 to 19

  591.                 k_max = FFMIN(opt_order, 20);

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

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

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

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

  596.                 }

  597. 

  598.                 // read coefficients 20 to 126

  599.                 k_max = FFMIN(opt_order, 127);

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

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

  602. 

  603.                 // read coefficients 127 to opt_order

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

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

  606. 

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

  608. 

  609.                 if (opt_order > 1)

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

  611.             }

  612. 

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

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

  615.         }

  616.     }

  617. 

  618.     // read LTP gain and lag values

  619.     if (sconf->long_term_prediction) {

  620.         use_ltp = get_bits1(gb);

  621. 

  622.         if (use_ltp) {

  623.             ltp_gain[0]   = decode_rice(gb, 1) << 3;

  624.             ltp_gain[1]   = decode_rice(gb, 2) << 3;

  625. 

  626.             ltp_gain[2]   = ltp_gain_values[get_unary(gb, 0, 4)][get_bits(gb, 2)];

  627. 

  628.             ltp_gain[3]   = decode_rice(gb, 2) << 3;

  629.             ltp_gain[4]   = decode_rice(gb, 1) << 3;

  630. 

  631.             ltp_lag       = get_bits(gb, ctx->ltp_lag_length);

  632.             ltp_lag      += FFMAX(4, opt_order + 1);

  633.         }

  634.     }

  635. 

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

  637.     if (ra_block) {

  638.         if (opt_order)

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

  640.         if (opt_order > 1)

  641.             raw_samples[1] = decode_rice(gb, s[0] + 3);

  642.         if (opt_order > 2)

  643.             raw_samples[2] = decode_rice(gb, s[0] + 1);

  644. 

  645.         start = FFMIN(opt_order, 3);

  646.     }

  647. 

  648.     // read all residuals

  649.     if (sconf->bgmc) {

  650.         // TODO: BGMC mode

  651.     } else {

  652.         int32_t *current_res = raw_samples + start;

  653. 

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

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

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

  657.      }

  658. 

  659.     // reverse long-term prediction

  660.     if (use_ltp) {

  661.         int ltp_smp;

  662. 

  663.         for (ltp_smp = FFMAX(ltp_lag - 2, 0); ltp_smp < block_length; ltp_smp++) {

  664.             int center = ltp_smp - ltp_lag;

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

  666.             int end    = center + 3;

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

  668.             int base;

  669. 

  670.             y = 1 << 6;

  671. 

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

  673.                 y += MUL64(ltp_gain[tab], raw_samples[base]);

  674. 

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

  676.         }

  677.     }

  678. 

  679.     // reconstruct all samples from residuals

  680.     if (ra_block) {

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

  682.             y = 1 << 19;

  683. 

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

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

  686. 

  687.             raw_samples[smp] -= y >> 20;

  688.             parcor_to_lpc(smp, quant_cof, lpc_cof);

  689.         }

  690.     } else {

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

  692.             parcor_to_lpc(k, quant_cof, lpc_cof);

  693. 

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

  695.         if (store_prev_samples)

  696.             memcpy(ctx->prev_raw_samples, raw_samples - sconf->max_order,

  697.                    sizeof(*ctx->prev_raw_samples) * sconf->max_order);

  698. 

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

  700.         if (*js_blocks && raw_other) {

  701.             int32_t *left, *right;

  702. 

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

  704.                 left  = raw_samples;

  705.                 right = raw_other;

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

  707.                 left  = raw_other;

  708.                 right = raw_samples;

  709.             }

  710. 

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

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

  713.         }

  714. 

  715.         // reconstruct shifted signal

  716.         if (*shift_lsbs)

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

  718.                 raw_samples[sb] >>= *shift_lsbs;

  719.     }

  720. 

  721.     // reconstruct raw samples

  722.     for (; smp < block_length; smp++) {

  723.         y = 1 << 19;

  724. 

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

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

  727. 

  728.         raw_samples[smp] -= y >> 20;

  729.     }

  730. 

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

  732.     if (store_prev_samples)

  733.         memcpy(raw_samples - sconf->max_order, ctx->prev_raw_samples,

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

  735. 

  736.     return 0;

  737. }

  738. 

  739. 

  740. /** Reads the block data.

  741.  */

  742. static int read_block_data(ALSDecContext *ctx, unsigned int ra_block,

  743.                            int32_t *raw_samples, unsigned int block_length,

  744.                            unsigned int *js_blocks, int32_t *raw_other)

  745. {

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

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

  748.     unsigned int shift_lsbs  = 0;

  749.     unsigned int k;

  750. 

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

  752.     if (get_bits1(gb)) {

  753.         if (read_var_block(ctx, ra_block, raw_samples, block_length, js_blocks,

  754.                            raw_other, &shift_lsbs))

  755.             return -1;

  756.     } else {

  757.         read_const_block(ctx, raw_samples, block_length, js_blocks);

  758.     }

  759. 

  760.     // TODO: read RLSLMS extension data

  761. 

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

  763.         align_get_bits(gb);

  764. 

  765.     if (shift_lsbs)

  766.         for (k = 0; k < block_length; k++)

  767.             raw_samples[k] <<= shift_lsbs;

  768. 

  769.     return 0;

  770. }

  771. 

  772. 

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

  774.  *  sets these samples to zero.

  775.  */

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

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

  778. {

  779.     unsigned int count = 0;

  780. 

  781.     while (b < b_max)

  782.         count += div_blocks[b];

  783. 

  784.     if (count)

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

  786. }

  787. 

  788. 

  789. /** Decodes blocks independently.

  790.  */

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

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

  793.                              unsigned int *js_blocks)

  794. {

  795.     int32_t *raw_sample;

  796.     unsigned int b;

  797.     raw_sample = ctx->raw_samples[c];

  798. 

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

  800.         if (read_block_data(ctx, ra_frame, raw_sample,

  801.                             div_blocks[b], &js_blocks[0], NULL)) {

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

  803.             zero_remaining(b, ctx->num_blocks, div_blocks, raw_sample);

  804.             return -1;

  805.         }

  806.         raw_sample += div_blocks[b];

  807.         ra_frame    = 0;

  808.     }

  809. 

  810.     return 0;

  811. }

  812. 

  813. 

  814. /** Decodes blocks dependently.

  815.  */

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

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

  818.                          unsigned int *js_blocks)

  819. {

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

  821.     unsigned int offset = 0;

  822.     int32_t *raw_samples_R;

  823.     int32_t *raw_samples_L;

  824.     unsigned int b;

  825. 

  826.     // decode all blocks

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

  828.         unsigned int s;

  829.         raw_samples_L = ctx->raw_samples[c    ] + offset;

  830.         raw_samples_R = ctx->raw_samples[c + 1] + offset;

  831.         if (read_block_data(ctx, ra_frame, raw_samples_L, div_blocks[b],

  832.                             &js_blocks[0], raw_samples_R) ||

  833.             read_block_data(ctx, ra_frame, raw_samples_R, div_blocks[b],

  834.                             &js_blocks[1], raw_samples_L)) {

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

  836.             zero_remaining(b, ctx->num_blocks, div_blocks, raw_samples_L);

  837.             zero_remaining(b, ctx->num_blocks, div_blocks, raw_samples_R);

  838.             return -1;

  839.         }

  840. 

  841.         // reconstruct joint-stereo blocks

  842.         if (js_blocks[0]) {

  843.             if (js_blocks[1])

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

  845. 

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

  847.                 raw_samples_L[s] = raw_samples_R[s] - raw_samples_L[s];

  848.         } else if (js_blocks[1]) {

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

  850.                 raw_samples_R[s] = raw_samples_R[s] + raw_samples_L[s];

  851.         }

  852. 

  853.         offset  += div_blocks[b];

  854.         ra_frame = 0;

  855.     }

  856. 

  857.     // store carryover raw samples,

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

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

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

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

  862. 

  863.     return 0;

  864. }

  865. 

  866. 

  867. /** Reads the frame data.

  868.  */

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

  870. {

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

  872.     AVCodecContext *avctx    = ctx->avctx;

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

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

  875.     unsigned int c;

  876.     unsigned int js_blocks[2];

  877. 

  878.     uint32_t bs_info = 0;

  879. 

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

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

  882.         skip_bits_long(gb, 32);

  883. 

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

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

  886.         align_get_bits(gb);

  887.     }

  888. 

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

  890.         int independent_bs = !sconf->joint_stereo;

  891. 

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

  893.             js_blocks[0] = 0;

  894.             js_blocks[1] = 0;

  895. 

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

  897. 

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

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

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

  901.                 if (bs_info >> 31)

  902.                     independent_bs = 2;

  903. 

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

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

  906.                 independent_bs = 1;

  907. 

  908.             if (independent_bs) {

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

  910.                     return -1;

  911. 

  912.                 independent_bs--;

  913.             } else {

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

  915.                     return -1;

  916. 

  917.                 c++;

  918.             }

  919. 

  920.             // store carryover raw samples

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

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

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

  924.         }

  925.     } else { // multi-channel coding

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

  927. 

  928.         // TODO: multi channel coding might use a temporary buffer instead as

  929.         //       the actual channel is not known when read_block-data is called

  930.         if (decode_blocks_ind(ctx, ra_frame, 0, div_blocks, js_blocks))

  931.             return -1;

  932.         // TODO: read_channel_data

  933.     }

  934. 

  935.     // TODO: read_diff_float_data

  936. 

  937.     return 0;

  938. }

  939. 

  940. 

  941. /** Decodes an ALS frame.

  942.  */

  943. static int decode_frame(AVCodecContext *avctx,

  944.                         void *data, int *data_size,

  945.                         AVPacket *avpkt)

  946. {

  947.     ALSDecContext *ctx       = avctx->priv_data;

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

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

  950.     int buffer_size          = avpkt->size;

  951.     int invalid_frame, size;

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

  953. 

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

  955. 

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

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

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

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

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

  961. 

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

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

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

  965.                                       sconf->frame_length);

  966.     else

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

  968. 

  969.     // decode the frame data

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

  971.         av_log(ctx->avctx, AV_LOG_WARNING,

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

  973. 

  974.     ctx->frame_id++;

  975. 

  976.     // check for size of decoded data

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

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

  979. 

  980.     if (size > *data_size) {

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

  982.         return -1;

  983.     }

  984. 

  985.     *data_size = size;

  986. 

  987.     // transform decoded frame into output format

  988.     #define INTERLEAVE_OUTPUT(bps)                                 \

  989.     {                                                              \

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

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

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

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

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

  995.     }

  996. 

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

  998.         INTERLEAVE_OUTPUT(16)

  999.     } else {

  1000.         INTERLEAVE_OUTPUT(32)

  1001.     }

  1002. 

  1003.     bytes_read = invalid_frame ? buffer_size :

  1004.                                  (get_bits_count(&ctx->gb) + 7) >> 3;

  1005. 

  1006.     return bytes_read;

  1007. }

  1008. 

  1009. 

  1010. /** Uninitializes the ALS decoder.

  1011.  */

  1012. static av_cold int decode_end(AVCodecContext *avctx)

  1013. {

  1014.     ALSDecContext *ctx = avctx->priv_data;

  1015. 

  1016.     av_freep(&ctx->sconf.chan_pos);

  1017. 

  1018.     av_freep(&ctx->quant_cof);

  1019.     av_freep(&ctx->lpc_cof);

  1020.     av_freep(&ctx->prev_raw_samples);

  1021.     av_freep(&ctx->raw_samples);

  1022.     av_freep(&ctx->raw_buffer);

  1023. 

  1024.     return 0;

  1025. }

  1026. 

  1027. 

  1028. /** Initializes the ALS decoder.

  1029.  */

  1030. static av_cold int decode_init(AVCodecContext *avctx)

  1031. {

  1032.     unsigned int c;

  1033.     unsigned int channel_size;

  1034.     ALSDecContext *ctx = avctx->priv_data;

  1035.     ALSSpecificConfig *sconf = &ctx->sconf;

  1036.     ctx->avctx = avctx;

  1037. 

  1038.     if (!avctx->extradata) {

  1039.         av_log(avctx, AV_LOG_ERROR, "Missing required ALS extradata.\n");

  1040.         return -1;

  1041.     }

  1042. 

  1043.     if (read_specific_config(ctx)) {

  1044.         av_log(avctx, AV_LOG_ERROR, "Reading ALSSpecificConfig failed.\n");

  1045.         decode_end(avctx);

  1046.         return -1;

  1047.     }

  1048. 

  1049.     if (check_specific_config(ctx)) {

  1050.         decode_end(avctx);

  1051.         return -1;

  1052.     }

  1053. 

  1054.     if (sconf->floating) {

  1055.         avctx->sample_fmt          = SAMPLE_FMT_FLT;

  1056.         avctx->bits_per_raw_sample = 32;

  1057.     } else {

  1058.         avctx->sample_fmt          = sconf->resolution > 1

  1059.                                      ? SAMPLE_FMT_S32 : SAMPLE_FMT_S16;

  1060.         avctx->bits_per_raw_sample = (sconf->resolution + 1) * 8;

  1061.     }

  1062. 

  1063.     // set lag value for long-term prediction

  1064.     ctx->ltp_lag_length = 8 + (avctx->sample_rate >=  96000) +

  1065.                               (avctx->sample_rate >= 192000);

  1066. 

  1067.     avctx->frame_size = sconf->frame_length;

  1068.     channel_size      = sconf->frame_length + sconf->max_order;

  1069. 

  1070.     ctx->prev_raw_samples = av_malloc (sizeof(*ctx->prev_raw_samples) * sconf->max_order);

  1071.     ctx->raw_buffer       = av_mallocz(sizeof(*ctx->     raw_buffer)  * avctx->channels * channel_size);

  1072.     ctx->raw_samples      = av_malloc (sizeof(*ctx->     raw_samples) * avctx->channels);

  1073. 

  1074.     // allocate previous raw sample buffer

  1075.     if (!ctx->prev_raw_samples || !ctx->raw_buffer|| !ctx->raw_samples) {

  1076.         av_log(avctx, AV_LOG_ERROR, "Allocating buffer memory failed.\n");

  1077.         decode_end(avctx);

  1078.         return AVERROR(ENOMEM);

  1079.     }

  1080. 

  1081.     // assign raw samples buffers

  1082.     ctx->raw_samples[0] = ctx->raw_buffer + sconf->max_order;

  1083.     for (c = 1; c < avctx->channels; c++)

  1084.         ctx->raw_samples[c] = ctx->raw_samples[c - 1] + channel_size;

  1085. 

  1086.     return 0;

  1087. }

  1088. 

  1089. 

  1090. /** Flushes (resets) the frame ID after seeking.

  1091.  */

  1092. static av_cold void flush(AVCodecContext *avctx)

  1093. {

  1094.     ALSDecContext *ctx = avctx->priv_data;

  1095. 

  1096.     ctx->frame_id = 0;

  1097. }

  1098. 

  1099. 

  1100. AVCodec als_decoder = {

  1101.     "als",

  1102.     CODEC_TYPE_AUDIO,

  1103.     CODEC_ID_MP4ALS,

  1104.     sizeof(ALSDecContext),

  1105.     decode_init,

  1106.     NULL,

  1107.     decode_end,

  1108.     decode_frame,

  1109.     .flush = flush,

  1110.     .capabilities = CODEC_CAP_SUBFRAMES,

  1111.     .long_name = NULL_IF_CONFIG_SMALL("MPEG-4 Audio Lossless Coding (ALS)"),

  1112. };