/* * MPEG-4 ALS decoder * Copyright (c) 2009 Thilo Borgmann * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file libavcodec/alsdec.c * MPEG-4 ALS decoder * @author Thilo Borgmann */ //#define DEBUG #include "avcodec.h" #include "get_bits.h" #include "unary.h" #include "mpeg4audio.h" #include "bytestream.h" #include /** Rice parameters and corresponding index offsets for decoding the * indices of scaled PARCOR values. The table choosen is set globally * by the encoder and stored in ALSSpecificConfig. */ static const int8_t parcor_rice_table[3][20][2] = { { {-52, 4}, {-29, 5}, {-31, 4}, { 19, 4}, {-16, 4}, { 12, 3}, { -7, 3}, { 9, 3}, { -5, 3}, { 6, 3}, { -4, 3}, { 3, 3}, { -3, 2}, { 3, 2}, { -2, 2}, { 3, 2}, { -1, 2}, { 2, 2}, { -1, 2}, { 2, 2} }, { {-58, 3}, {-42, 4}, {-46, 4}, { 37, 5}, {-36, 4}, { 29, 4}, {-29, 4}, { 25, 4}, {-23, 4}, { 20, 4}, {-17, 4}, { 16, 4}, {-12, 4}, { 12, 3}, {-10, 4}, { 7, 3}, { -4, 4}, { 3, 3}, { -1, 3}, { 1, 3} }, { {-59, 3}, {-45, 5}, {-50, 4}, { 38, 4}, {-39, 4}, { 32, 4}, {-30, 4}, { 25, 3}, {-23, 3}, { 20, 3}, {-20, 3}, { 16, 3}, {-13, 3}, { 10, 3}, { -7, 3}, { 3, 3}, { 0, 3}, { -1, 3}, { 2, 3}, { -1, 2} } }; /** Scaled PARCOR values used for the first two PARCOR coefficients. * To be indexed by the Rice coded indices. * Generated by: parcor_scaled_values[i] = 32 + ((i * (i+1)) << 7) - (1 << 20) * Actual values are divided by 32 in order to be stored in 16 bits. */ static const int16_t parcor_scaled_values[] = { -1048544 / 32, -1048288 / 32, -1047776 / 32, -1047008 / 32, -1045984 / 32, -1044704 / 32, -1043168 / 32, -1041376 / 32, -1039328 / 32, -1037024 / 32, -1034464 / 32, -1031648 / 32, -1028576 / 32, -1025248 / 32, -1021664 / 32, -1017824 / 32, -1013728 / 32, -1009376 / 32, -1004768 / 32, -999904 / 32, -994784 / 32, -989408 / 32, -983776 / 32, -977888 / 32, -971744 / 32, -965344 / 32, -958688 / 32, -951776 / 32, -944608 / 32, -937184 / 32, -929504 / 32, -921568 / 32, -913376 / 32, -904928 / 32, -896224 / 32, -887264 / 32, -878048 / 32, -868576 / 32, -858848 / 32, -848864 / 32, -838624 / 32, -828128 / 32, -817376 / 32, -806368 / 32, -795104 / 32, -783584 / 32, -771808 / 32, -759776 / 32, -747488 / 32, -734944 / 32, -722144 / 32, -709088 / 32, -695776 / 32, -682208 / 32, -668384 / 32, -654304 / 32, -639968 / 32, -625376 / 32, -610528 / 32, -595424 / 32, -580064 / 32, -564448 / 32, -548576 / 32, -532448 / 32, -516064 / 32, -499424 / 32, -482528 / 32, -465376 / 32, -447968 / 32, -430304 / 32, -412384 / 32, -394208 / 32, -375776 / 32, -357088 / 32, -338144 / 32, -318944 / 32, -299488 / 32, -279776 / 32, -259808 / 32, -239584 / 32, -219104 / 32, -198368 / 32, -177376 / 32, -156128 / 32, -134624 / 32, -112864 / 32, -90848 / 32, -68576 / 32, -46048 / 32, -23264 / 32, -224 / 32, 23072 / 32, 46624 / 32, 70432 / 32, 94496 / 32, 118816 / 32, 143392 / 32, 168224 / 32, 193312 / 32, 218656 / 32, 244256 / 32, 270112 / 32, 296224 / 32, 322592 / 32, 349216 / 32, 376096 / 32, 403232 / 32, 430624 / 32, 458272 / 32, 486176 / 32, 514336 / 32, 542752 / 32, 571424 / 32, 600352 / 32, 629536 / 32, 658976 / 32, 688672 / 32, 718624 / 32, 748832 / 32, 779296 / 32, 810016 / 32, 840992 / 32, 872224 / 32, 903712 / 32, 935456 / 32, 967456 / 32, 999712 / 32, 1032224 / 32 }; /** Gain values of p(0) for long-term prediction. * To be indexed by the Rice coded indices. */ static const uint8_t ltp_gain_values [4][4] = { { 0, 8, 16, 24}, {32, 40, 48, 56}, {64, 70, 76, 82}, {88, 92, 96, 100} }; enum RA_Flag { RA_FLAG_NONE, RA_FLAG_FRAMES, RA_FLAG_HEADER }; typedef struct { uint32_t samples; ///< number of samples, 0xFFFFFFFF if unknown int resolution; ///< 000 = 8-bit; 001 = 16-bit; 010 = 24-bit; 011 = 32-bit int floating; ///< 1 = IEEE 32-bit floating-point, 0 = integer int frame_length; ///< frame length for each frame (last frame may differ) int ra_distance; ///< distance between RA frames (in frames, 0...255) enum RA_Flag ra_flag; ///< indicates where the size of ra units is stored int adapt_order; ///< adaptive order: 1 = on, 0 = off int coef_table; ///< table index of Rice code parameters int long_term_prediction; ///< long term prediction (LTP): 1 = on, 0 = off int max_order; ///< maximum prediction order (0..1023) int block_switching; ///< number of block switching levels int bgmc; ///< "Block Gilbert-Moore Code": 1 = on, 0 = off (Rice coding only) int sb_part; ///< sub-block partition int joint_stereo; ///< joint stereo: 1 = on, 0 = off int mc_coding; ///< extended inter-channel coding (multi channel coding): 1 = on, 0 = off int chan_config; ///< indicates that a chan_config_info field is present int chan_sort; ///< channel rearrangement: 1 = on, 0 = off int rlslms; ///< use "Recursive Least Square-Least Mean Square" predictor: 1 = on, 0 = off int chan_config_info; ///< mapping of channels to loudspeaker locations. Unused until setting channel configuration is implemented. int *chan_pos; ///< original channel positions uint32_t header_size; ///< header size of original audio file in bytes, provided for debugging uint32_t trailer_size; ///< trailer size of original audio file in bytes, provided for debugging } ALSSpecificConfig; typedef struct { AVCodecContext *avctx; ALSSpecificConfig sconf; GetBitContext gb; unsigned int cur_frame_length; ///< length of the current frame to decode unsigned int frame_id; ///< the frame ID / number of the current frame unsigned int js_switch; ///< if true, joint-stereo decoding is enforced unsigned int num_blocks; ///< number of blocks used in the current frame int ltp_lag_length; ///< number of bits used for ltp lag value int32_t *quant_cof; ///< quantized parcor coefficients int32_t *lpc_cof; ///< coefficients of the direct form prediction filter int32_t *prev_raw_samples; ///< contains unshifted raw samples from the previous block int32_t **raw_samples; ///< decoded raw samples for each channel int32_t *raw_buffer; ///< contains all decoded raw samples including carryover samples } ALSDecContext; static av_cold void dprint_specific_config(ALSDecContext *ctx) { #ifdef DEBUG AVCodecContext *avctx = ctx->avctx; ALSSpecificConfig *sconf = &ctx->sconf; dprintf(avctx, "resolution = %i\n", sconf->resolution); dprintf(avctx, "floating = %i\n", sconf->floating); dprintf(avctx, "frame_length = %i\n", sconf->frame_length); dprintf(avctx, "ra_distance = %i\n", sconf->ra_distance); dprintf(avctx, "ra_flag = %i\n", sconf->ra_flag); dprintf(avctx, "adapt_order = %i\n", sconf->adapt_order); dprintf(avctx, "coef_table = %i\n", sconf->coef_table); dprintf(avctx, "long_term_prediction = %i\n", sconf->long_term_prediction); dprintf(avctx, "max_order = %i\n", sconf->max_order); dprintf(avctx, "block_switching = %i\n", sconf->block_switching); dprintf(avctx, "bgmc = %i\n", sconf->bgmc); dprintf(avctx, "sb_part = %i\n", sconf->sb_part); dprintf(avctx, "joint_stereo = %i\n", sconf->joint_stereo); dprintf(avctx, "mc_coding = %i\n", sconf->mc_coding); dprintf(avctx, "chan_config = %i\n", sconf->chan_config); dprintf(avctx, "chan_sort = %i\n", sconf->chan_sort); dprintf(avctx, "RLSLMS = %i\n", sconf->rlslms); dprintf(avctx, "chan_config_info = %i\n", sconf->chan_config_info); dprintf(avctx, "header_size = %i\n", sconf->header_size); dprintf(avctx, "trailer_size = %i\n", sconf->trailer_size); #endif } /** Reads an ALSSpecificConfig from a buffer into the output struct. */ static av_cold int read_specific_config(ALSDecContext *ctx) { GetBitContext gb; uint64_t ht_size; int i, config_offset, crc_enabled; MPEG4AudioConfig m4ac; ALSSpecificConfig *sconf = &ctx->sconf; AVCodecContext *avctx = ctx->avctx; uint32_t als_id; init_get_bits(&gb, avctx->extradata, avctx->extradata_size * 8); config_offset = ff_mpeg4audio_get_config(&m4ac, avctx->extradata, avctx->extradata_size); if (config_offset < 0) return -1; skip_bits_long(&gb, config_offset); if (get_bits_left(&gb) < (30 << 3)) return -1; // read the fixed items als_id = get_bits_long(&gb, 32); avctx->sample_rate = m4ac.sample_rate; skip_bits_long(&gb, 32); // sample rate already known sconf->samples = get_bits_long(&gb, 32); avctx->channels = m4ac.channels; skip_bits(&gb, 16); // number of channels already knwon skip_bits(&gb, 3); // skip file_type sconf->resolution = get_bits(&gb, 3); sconf->floating = get_bits1(&gb); skip_bits1(&gb); // skip msb_first sconf->frame_length = get_bits(&gb, 16) + 1; sconf->ra_distance = get_bits(&gb, 8); sconf->ra_flag = get_bits(&gb, 2); sconf->adapt_order = get_bits1(&gb); sconf->coef_table = get_bits(&gb, 2); sconf->long_term_prediction = get_bits1(&gb); sconf->max_order = get_bits(&gb, 10); sconf->block_switching = get_bits(&gb, 2); sconf->bgmc = get_bits1(&gb); sconf->sb_part = get_bits1(&gb); sconf->joint_stereo = get_bits1(&gb); sconf->mc_coding = get_bits1(&gb); sconf->chan_config = get_bits1(&gb); sconf->chan_sort = get_bits1(&gb); crc_enabled = get_bits1(&gb); sconf->rlslms = get_bits1(&gb); skip_bits(&gb, 5); // skip 5 reserved bits skip_bits1(&gb); // skip aux_data_enabled // check for ALSSpecificConfig struct if (als_id != MKBETAG('A','L','S','\0')) return -1; ctx->cur_frame_length = sconf->frame_length; // allocate quantized parcor coefficient buffer if (!(ctx->quant_cof = av_malloc(sizeof(*ctx->quant_cof) * sconf->max_order)) || !(ctx->lpc_cof = av_malloc(sizeof(*ctx->lpc_cof) * sconf->max_order))) { av_log(avctx, AV_LOG_ERROR, "Allocating buffer memory failed.\n"); return AVERROR(ENOMEM); } // read channel config if (sconf->chan_config) sconf->chan_config_info = get_bits(&gb, 16); // TODO: use this to set avctx->channel_layout // read channel sorting if (sconf->chan_sort && avctx->channels > 1) { int chan_pos_bits = av_ceil_log2(avctx->channels); int bits_needed = avctx->channels * chan_pos_bits + 7; if (get_bits_left(&gb) < bits_needed) return -1; if (!(sconf->chan_pos = av_malloc(avctx->channels * sizeof(*sconf->chan_pos)))) return AVERROR(ENOMEM); for (i = 0; i < avctx->channels; i++) sconf->chan_pos[i] = get_bits(&gb, chan_pos_bits); align_get_bits(&gb); // TODO: use this to actually do channel sorting } else { sconf->chan_sort = 0; } // read fixed header and trailer sizes, // if size = 0xFFFFFFFF then there is no data field! if (get_bits_left(&gb) < 64) return -1; sconf->header_size = get_bits_long(&gb, 32); sconf->trailer_size = get_bits_long(&gb, 32); if (sconf->header_size == 0xFFFFFFFF) sconf->header_size = 0; if (sconf->trailer_size == 0xFFFFFFFF) sconf->trailer_size = 0; ht_size = ((int64_t)(sconf->header_size) + (int64_t)(sconf->trailer_size)) << 3; // skip the header and trailer data if (get_bits_left(&gb) < ht_size) return -1; if (ht_size > INT32_MAX) return -1; skip_bits_long(&gb, ht_size); // skip the crc data if (crc_enabled) { if (get_bits_left(&gb) < 32) return -1; skip_bits_long(&gb, 32); } // no need to read the rest of ALSSpecificConfig (ra_unit_size & aux data) dprint_specific_config(ctx); return 0; } /** Checks the ALSSpecificConfig for unsupported features. */ static int check_specific_config(ALSDecContext *ctx) { ALSSpecificConfig *sconf = &ctx->sconf; int error = 0; // report unsupported feature and set error value #define MISSING_ERR(cond, str, errval) \ { \ if (cond) { \ av_log_missing_feature(ctx->avctx, str, 0); \ error = errval; \ } \ } MISSING_ERR(sconf->floating, "Floating point decoding", -1); MISSING_ERR(sconf->bgmc, "BGMC entropy decoding", -1); MISSING_ERR(sconf->mc_coding, "Multi-channel correlation", -1); MISSING_ERR(sconf->rlslms, "Adaptive RLS-LMS prediction", -1); MISSING_ERR(sconf->chan_sort, "Channel sorting", 0); return error; } /** Parses the bs_info field to extract the block partitioning used in * block switching mode, refer to ISO/IEC 14496-3, section 11.6.2. */ static void parse_bs_info(const uint32_t bs_info, unsigned int n, unsigned int div, unsigned int **div_blocks, unsigned int *num_blocks) { if (n < 31 && ((bs_info << n) & 0x40000000)) { // if the level is valid and the investigated bit n is set // then recursively check both children at bits (2n+1) and (2n+2) n *= 2; div += 1; parse_bs_info(bs_info, n + 1, div, div_blocks, num_blocks); parse_bs_info(bs_info, n + 2, div, div_blocks, num_blocks); } else { // else the bit is not set or the last level has been reached // (bit implicitly not set) **div_blocks = div; (*div_blocks)++; (*num_blocks)++; } } /** Reads and decodes a Rice codeword. */ static int32_t decode_rice(GetBitContext *gb, unsigned int k) { int max = get_bits_left(gb) - k; int q = get_unary(gb, 0, max); int r = k ? get_bits1(gb) : !(q & 1); if (k > 1) { q <<= (k - 1); q += get_bits_long(gb, k - 1); } else if (!k) { q >>= 1; } return r ? q : ~q; } /** Converts PARCOR coefficient k to direct filter coefficient. */ static void parcor_to_lpc(unsigned int k, const int32_t *par, int32_t *cof) { int i, j; for (i = 0, j = k - 1; i < j; i++, j--) { int tmp1 = ((MUL64(par[k], cof[j]) + (1 << 19)) >> 20); cof[j] += ((MUL64(par[k], cof[i]) + (1 << 19)) >> 20); cof[i] += tmp1; } if (i == j) cof[i] += ((MUL64(par[k], cof[j]) + (1 << 19)) >> 20); cof[k] = par[k]; } /** Reads block switching field if necessary and sets actual block sizes. * Also assures that the block sizes of the last frame correspond to the * actual number of samples. */ static void get_block_sizes(ALSDecContext *ctx, unsigned int *div_blocks, uint32_t *bs_info) { ALSSpecificConfig *sconf = &ctx->sconf; GetBitContext *gb = &ctx->gb; unsigned int *ptr_div_blocks = div_blocks; unsigned int b; if (sconf->block_switching) { unsigned int bs_info_len = 1 << (sconf->block_switching + 2); *bs_info = get_bits_long(gb, bs_info_len); *bs_info <<= (32 - bs_info_len); } ctx->num_blocks = 0; parse_bs_info(*bs_info, 0, 0, &ptr_div_blocks, &ctx->num_blocks); // The last frame may have an overdetermined block structure given in // the bitstream. In that case the defined block structure would need // more samples than available to be consistent. // The block structure is actually used but the block sizes are adapted // to fit the actual number of available samples. // Example: 5 samples, 2nd level block sizes: 2 2 2 2. // This results in the actual block sizes: 2 2 1 0. // This is not specified in 14496-3 but actually done by the reference // codec RM22 revision 2. // This appears to happen in case of an odd number of samples in the last // frame which is actually not allowed by the block length switching part // of 14496-3. // The ALS conformance files feature an odd number of samples in the last // frame. for (b = 0; b < ctx->num_blocks; b++) div_blocks[b] = ctx->sconf.frame_length >> div_blocks[b]; if (ctx->cur_frame_length != ctx->sconf.frame_length) { unsigned int remaining = ctx->cur_frame_length; for (b = 0; b < ctx->num_blocks; b++) { if (remaining < div_blocks[b]) { div_blocks[b] = remaining; ctx->num_blocks = b + 1; break; } remaining -= div_blocks[b]; } } } /** Reads the block data for a constant block */ static void read_const_block(ALSDecContext *ctx, int32_t *raw_samples, unsigned int block_length, unsigned int *js_blocks) { ALSSpecificConfig *sconf = &ctx->sconf; AVCodecContext *avctx = ctx->avctx; GetBitContext *gb = &ctx->gb; int32_t const_val = 0; unsigned int const_block, k; const_block = get_bits1(gb); // 1 = constant value, 0 = zero block (silence) *js_blocks = get_bits1(gb); // skip 5 reserved bits skip_bits(gb, 5); if (const_block) { unsigned int const_val_bits = sconf->floating ? 24 : avctx->bits_per_raw_sample; const_val = get_sbits_long(gb, const_val_bits); } // write raw samples into buffer for (k = 0; k < block_length; k++) raw_samples[k] = const_val; } /** Reads the block data for a non-constant block */ static int read_var_block(ALSDecContext *ctx, unsigned int ra_block, int32_t *raw_samples, unsigned int block_length, unsigned int *js_blocks, int32_t *raw_other, unsigned int *shift_lsbs) { ALSSpecificConfig *sconf = &ctx->sconf; AVCodecContext *avctx = ctx->avctx; GetBitContext *gb = &ctx->gb; unsigned int k; unsigned int s[8]; unsigned int sub_blocks, log2_sub_blocks, sb_length; unsigned int opt_order = 1; int32_t *quant_cof = ctx->quant_cof; int32_t *lpc_cof = ctx->lpc_cof; unsigned int start = 0; int smp = 0; int sb, store_prev_samples; int64_t y; int use_ltp = 0; int ltp_lag = 0; int ltp_gain[5]; *js_blocks = get_bits1(gb); // determine the number of subblocks for entropy decoding if (!sconf->bgmc && !sconf->sb_part) { log2_sub_blocks = 0; } else { if (sconf->bgmc && sconf->sb_part) log2_sub_blocks = get_bits(gb, 2); else log2_sub_blocks = 2 * get_bits1(gb); } sub_blocks = 1 << log2_sub_blocks; // do not continue in case of a damaged stream since // block_length must be evenly divisible by sub_blocks if (block_length & (sub_blocks - 1)) { av_log(avctx, AV_LOG_WARNING, "Block length is not evenly divisible by the number of subblocks.\n"); return -1; } sb_length = block_length >> log2_sub_blocks; if (sconf->bgmc) { // TODO: BGMC mode } else { s[0] = get_bits(gb, 4 + (sconf->resolution > 1)); for (k = 1; k < sub_blocks; k++) s[k] = s[k - 1] + decode_rice(gb, 0); } if (get_bits1(gb)) *shift_lsbs = get_bits(gb, 4) + 1; store_prev_samples = (*js_blocks && raw_other) || *shift_lsbs; if (!sconf->rlslms) { if (sconf->adapt_order) { int opt_order_length = av_ceil_log2(av_clip((block_length >> 3) - 1, 2, sconf->max_order + 1)); opt_order = get_bits(gb, opt_order_length); } else { opt_order = sconf->max_order; } if (opt_order) { int add_base; if (sconf->coef_table == 3) { add_base = 0x7F; // read coefficient 0 quant_cof[0] = 32 * parcor_scaled_values[get_bits(gb, 7)]; // read coefficient 1 if (opt_order > 1) quant_cof[1] = -32 * parcor_scaled_values[get_bits(gb, 7)]; // read coefficients 2 to opt_order for (k = 2; k < opt_order; k++) quant_cof[k] = get_bits(gb, 7); } else { int k_max; add_base = 1; // read coefficient 0 to 19 k_max = FFMIN(opt_order, 20); for (k = 0; k < k_max; k++) { int rice_param = parcor_rice_table[sconf->coef_table][k][1]; int offset = parcor_rice_table[sconf->coef_table][k][0]; quant_cof[k] = decode_rice(gb, rice_param) + offset; } // read coefficients 20 to 126 k_max = FFMIN(opt_order, 127); for (; k < k_max; k++) quant_cof[k] = decode_rice(gb, 2) + (k & 1); // read coefficients 127 to opt_order for (; k < opt_order; k++) quant_cof[k] = decode_rice(gb, 1); quant_cof[0] = 32 * parcor_scaled_values[quant_cof[0] + 64]; if (opt_order > 1) quant_cof[1] = -32 * parcor_scaled_values[quant_cof[1] + 64]; } for (k = 2; k < opt_order; k++) quant_cof[k] = (quant_cof[k] << 14) + (add_base << 13); } } // read LTP gain and lag values if (sconf->long_term_prediction) { use_ltp = get_bits1(gb); if (use_ltp) { ltp_gain[0] = decode_rice(gb, 1) << 3; ltp_gain[1] = decode_rice(gb, 2) << 3; ltp_gain[2] = ltp_gain_values[get_unary(gb, 0, 4)][get_bits(gb, 2)]; ltp_gain[3] = decode_rice(gb, 2) << 3; ltp_gain[4] = decode_rice(gb, 1) << 3; ltp_lag = get_bits(gb, ctx->ltp_lag_length); ltp_lag += FFMAX(4, opt_order + 1); } } // read first value and residuals in case of a random access block if (ra_block) { if (opt_order) raw_samples[0] = decode_rice(gb, avctx->bits_per_raw_sample - 4); if (opt_order > 1) raw_samples[1] = decode_rice(gb, s[0] + 3); if (opt_order > 2) raw_samples[2] = decode_rice(gb, s[0] + 1); start = FFMIN(opt_order, 3); } // read all residuals if (sconf->bgmc) { // TODO: BGMC mode } else { int32_t *current_res = raw_samples + start; for (sb = 0; sb < sub_blocks; sb++, start = 0) for (; start < sb_length; start++) *current_res++ = decode_rice(gb, s[sb]); } // reverse long-term prediction if (use_ltp) { int ltp_smp; for (ltp_smp = FFMAX(ltp_lag - 2, 0); ltp_smp < block_length; ltp_smp++) { int center = ltp_smp - ltp_lag; int begin = FFMAX(0, center - 2); int end = center + 3; int tab = 5 - (end - begin); int base; y = 1 << 6; for (base = begin; base < end; base++, tab++) y += MUL64(ltp_gain[tab], raw_samples[base]); raw_samples[ltp_smp] += y >> 7; } } // reconstruct all samples from residuals if (ra_block) { for (smp = 0; smp < opt_order; smp++) { y = 1 << 19; for (sb = 0; sb < smp; sb++) y += MUL64(lpc_cof[sb],raw_samples[smp - (sb + 1)]); raw_samples[smp] -= y >> 20; parcor_to_lpc(smp, quant_cof, lpc_cof); } } else { for (k = 0; k < opt_order; k++) parcor_to_lpc(k, quant_cof, lpc_cof); // store previous samples in case that they have to be altered if (store_prev_samples) memcpy(ctx->prev_raw_samples, raw_samples - sconf->max_order, sizeof(*ctx->prev_raw_samples) * sconf->max_order); // reconstruct difference signal for prediction (joint-stereo) if (*js_blocks && raw_other) { int32_t *left, *right; if (raw_other > raw_samples) { // D = R - L left = raw_samples; right = raw_other; } else { // D = R - L left = raw_other; right = raw_samples; } for (sb = -1; sb >= -sconf->max_order; sb--) raw_samples[sb] = right[sb] - left[sb]; } // reconstruct shifted signal if (*shift_lsbs) for (sb = -1; sb >= -sconf->max_order; sb--) raw_samples[sb] >>= *shift_lsbs; } // reconstruct raw samples for (; smp < block_length; smp++) { y = 1 << 19; for (sb = 0; sb < opt_order; sb++) y += MUL64(lpc_cof[sb],raw_samples[smp - (sb + 1)]); raw_samples[smp] -= y >> 20; } // restore previous samples in case that they have been altered if (store_prev_samples) memcpy(raw_samples - sconf->max_order, ctx->prev_raw_samples, sizeof(*raw_samples) * sconf->max_order); return 0; } /** Reads the block data. */ static int read_block_data(ALSDecContext *ctx, unsigned int ra_block, int32_t *raw_samples, unsigned int block_length, unsigned int *js_blocks, int32_t *raw_other) { ALSSpecificConfig *sconf = &ctx->sconf; GetBitContext *gb = &ctx->gb; unsigned int shift_lsbs = 0; unsigned int k; // read block type flag and read the samples accordingly if (get_bits1(gb)) { if (read_var_block(ctx, ra_block, raw_samples, block_length, js_blocks, raw_other, &shift_lsbs)) return -1; } else { read_const_block(ctx, raw_samples, block_length, js_blocks); } // TODO: read RLSLMS extension data if (!sconf->mc_coding || ctx->js_switch) align_get_bits(gb); if (shift_lsbs) for (k = 0; k < block_length; k++) raw_samples[k] <<= shift_lsbs; return 0; } /** Computes the number of samples left to decode for the current frame and * sets these samples to zero. */ static void zero_remaining(unsigned int b, unsigned int b_max, const unsigned int *div_blocks, int32_t *buf) { unsigned int count = 0; while (b < b_max) count += div_blocks[b]; if (count) memset(buf, 0, sizeof(*buf) * count); } /** Decodes blocks independently. */ static int decode_blocks_ind(ALSDecContext *ctx, unsigned int ra_frame, unsigned int c, const unsigned int *div_blocks, unsigned int *js_blocks) { int32_t *raw_sample; unsigned int b; raw_sample = ctx->raw_samples[c]; for (b = 0; b < ctx->num_blocks; b++) { if (read_block_data(ctx, ra_frame, raw_sample, div_blocks[b], &js_blocks[0], NULL)) { // damaged block, write zero for the rest of the frame zero_remaining(b, ctx->num_blocks, div_blocks, raw_sample); return -1; } raw_sample += div_blocks[b]; ra_frame = 0; } return 0; } /** Decodes blocks dependently. */ static int decode_blocks(ALSDecContext *ctx, unsigned int ra_frame, unsigned int c, const unsigned int *div_blocks, unsigned int *js_blocks) { ALSSpecificConfig *sconf = &ctx->sconf; unsigned int offset = 0; int32_t *raw_samples_R; int32_t *raw_samples_L; unsigned int b; // decode all blocks for (b = 0; b < ctx->num_blocks; b++) { unsigned int s; raw_samples_L = ctx->raw_samples[c ] + offset; raw_samples_R = ctx->raw_samples[c + 1] + offset; if (read_block_data(ctx, ra_frame, raw_samples_L, div_blocks[b], &js_blocks[0], raw_samples_R) || read_block_data(ctx, ra_frame, raw_samples_R, div_blocks[b], &js_blocks[1], raw_samples_L)) { // damaged block, write zero for the rest of the frame zero_remaining(b, ctx->num_blocks, div_blocks, raw_samples_L); zero_remaining(b, ctx->num_blocks, div_blocks, raw_samples_R); return -1; } // reconstruct joint-stereo blocks if (js_blocks[0]) { if (js_blocks[1]) av_log(ctx->avctx, AV_LOG_WARNING, "Invalid channel pair!\n"); for (s = 0; s < div_blocks[b]; s++) raw_samples_L[s] = raw_samples_R[s] - raw_samples_L[s]; } else if (js_blocks[1]) { for (s = 0; s < div_blocks[b]; s++) raw_samples_R[s] = raw_samples_R[s] + raw_samples_L[s]; } offset += div_blocks[b]; ra_frame = 0; } // store carryover raw samples, // the others channel raw samples are stored by the calling function. memmove(ctx->raw_samples[c] - sconf->max_order, ctx->raw_samples[c] - sconf->max_order + sconf->frame_length, sizeof(*ctx->raw_samples[c]) * sconf->max_order); return 0; } /** Reads the frame data. */ static int read_frame_data(ALSDecContext *ctx, unsigned int ra_frame) { ALSSpecificConfig *sconf = &ctx->sconf; AVCodecContext *avctx = ctx->avctx; GetBitContext *gb = &ctx->gb; unsigned int div_blocks[32]; ///< block sizes. unsigned int c; unsigned int js_blocks[2]; uint32_t bs_info = 0; // skip the size of the ra unit if present in the frame if (sconf->ra_flag == RA_FLAG_FRAMES && ra_frame) skip_bits_long(gb, 32); if (sconf->mc_coding && sconf->joint_stereo) { ctx->js_switch = get_bits1(gb); align_get_bits(gb); } if (!sconf->mc_coding || ctx->js_switch) { int independent_bs = !sconf->joint_stereo; for (c = 0; c < avctx->channels; c++) { js_blocks[0] = 0; js_blocks[1] = 0; get_block_sizes(ctx, div_blocks, &bs_info); // if joint_stereo and block_switching is set, independent decoding // is signaled via the first bit of bs_info if (sconf->joint_stereo && sconf->block_switching) if (bs_info >> 31) independent_bs = 2; // if this is the last channel, it has to be decoded independently if (c == avctx->channels - 1) independent_bs = 1; if (independent_bs) { if (decode_blocks_ind(ctx, ra_frame, c, div_blocks, js_blocks)) return -1; independent_bs--; } else { if (decode_blocks(ctx, ra_frame, c, div_blocks, js_blocks)) return -1; c++; } // store carryover raw samples memmove(ctx->raw_samples[c] - sconf->max_order, ctx->raw_samples[c] - sconf->max_order + sconf->frame_length, sizeof(*ctx->raw_samples[c]) * sconf->max_order); } } else { // multi-channel coding get_block_sizes(ctx, div_blocks, &bs_info); // TODO: multi channel coding might use a temporary buffer instead as // the actual channel is not known when read_block-data is called if (decode_blocks_ind(ctx, ra_frame, 0, div_blocks, js_blocks)) return -1; // TODO: read_channel_data } // TODO: read_diff_float_data return 0; } /** Decodes an ALS frame. */ static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt) { ALSDecContext *ctx = avctx->priv_data; ALSSpecificConfig *sconf = &ctx->sconf; const uint8_t *buffer = avpkt->data; int buffer_size = avpkt->size; int invalid_frame, size; unsigned int c, sample, ra_frame, bytes_read, shift; init_get_bits(&ctx->gb, buffer, buffer_size * 8); // In the case that the distance between random access frames is set to zero // (sconf->ra_distance == 0) no frame is treated as a random access frame. // For the first frame, if prediction is used, all samples used from the // previous frame are assumed to be zero. ra_frame = sconf->ra_distance && !(ctx->frame_id % sconf->ra_distance); // the last frame to decode might have a different length if (sconf->samples != 0xFFFFFFFF) ctx->cur_frame_length = FFMIN(sconf->samples - ctx->frame_id * (uint64_t) sconf->frame_length, sconf->frame_length); else ctx->cur_frame_length = sconf->frame_length; // decode the frame data if ((invalid_frame = read_frame_data(ctx, ra_frame) < 0)) av_log(ctx->avctx, AV_LOG_WARNING, "Reading frame data failed. Skipping RA unit.\n"); ctx->frame_id++; // check for size of decoded data size = ctx->cur_frame_length * avctx->channels * (av_get_bits_per_sample_format(avctx->sample_fmt) >> 3); if (size > *data_size) { av_log(avctx, AV_LOG_ERROR, "Decoded data exceeds buffer size.\n"); return -1; } *data_size = size; // transform decoded frame into output format #define INTERLEAVE_OUTPUT(bps) \ { \ int##bps##_t *dest = (int##bps##_t*) data; \ shift = bps - ctx->avctx->bits_per_raw_sample; \ for (sample = 0; sample < ctx->cur_frame_length; sample++) \ for (c = 0; c < avctx->channels; c++) \ *dest++ = ctx->raw_samples[c][sample] << shift; \ } if (ctx->avctx->bits_per_raw_sample <= 16) { INTERLEAVE_OUTPUT(16) } else { INTERLEAVE_OUTPUT(32) } bytes_read = invalid_frame ? buffer_size : (get_bits_count(&ctx->gb) + 7) >> 3; return bytes_read; } /** Uninitializes the ALS decoder. */ static av_cold int decode_end(AVCodecContext *avctx) { ALSDecContext *ctx = avctx->priv_data; av_freep(&ctx->sconf.chan_pos); av_freep(&ctx->quant_cof); av_freep(&ctx->lpc_cof); av_freep(&ctx->prev_raw_samples); av_freep(&ctx->raw_samples); av_freep(&ctx->raw_buffer); return 0; } /** Initializes the ALS decoder. */ static av_cold int decode_init(AVCodecContext *avctx) { unsigned int c; unsigned int channel_size; ALSDecContext *ctx = avctx->priv_data; ALSSpecificConfig *sconf = &ctx->sconf; ctx->avctx = avctx; if (!avctx->extradata) { av_log(avctx, AV_LOG_ERROR, "Missing required ALS extradata.\n"); return -1; } if (read_specific_config(ctx)) { av_log(avctx, AV_LOG_ERROR, "Reading ALSSpecificConfig failed.\n"); decode_end(avctx); return -1; } if (check_specific_config(ctx)) { decode_end(avctx); return -1; } if (sconf->floating) { avctx->sample_fmt = SAMPLE_FMT_FLT; avctx->bits_per_raw_sample = 32; } else { avctx->sample_fmt = sconf->resolution > 1 ? SAMPLE_FMT_S32 : SAMPLE_FMT_S16; avctx->bits_per_raw_sample = (sconf->resolution + 1) * 8; } // set lag value for long-term prediction ctx->ltp_lag_length = 8 + (avctx->sample_rate >= 96000) + (avctx->sample_rate >= 192000); avctx->frame_size = sconf->frame_length; channel_size = sconf->frame_length + sconf->max_order; ctx->prev_raw_samples = av_malloc (sizeof(*ctx->prev_raw_samples) * sconf->max_order); ctx->raw_buffer = av_mallocz(sizeof(*ctx-> raw_buffer) * avctx->channels * channel_size); ctx->raw_samples = av_malloc (sizeof(*ctx-> raw_samples) * avctx->channels); // allocate previous raw sample buffer if (!ctx->prev_raw_samples || !ctx->raw_buffer|| !ctx->raw_samples) { av_log(avctx, AV_LOG_ERROR, "Allocating buffer memory failed.\n"); decode_end(avctx); return AVERROR(ENOMEM); } // assign raw samples buffers ctx->raw_samples[0] = ctx->raw_buffer + sconf->max_order; for (c = 1; c < avctx->channels; c++) ctx->raw_samples[c] = ctx->raw_samples[c - 1] + channel_size; return 0; } /** Flushes (resets) the frame ID after seeking. */ static av_cold void flush(AVCodecContext *avctx) { ALSDecContext *ctx = avctx->priv_data; ctx->frame_id = 0; } AVCodec als_decoder = { "als", CODEC_TYPE_AUDIO, CODEC_ID_MP4ALS, sizeof(ALSDecContext), decode_init, NULL, decode_end, decode_frame, .flush = flush, .capabilities = CODEC_CAP_SUBFRAMES, .long_name = NULL_IF_CONFIG_SMALL("MPEG-4 Audio Lossless Coding (ALS)"), };