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alsdec.c
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/*
* MPEG-4 ALS decoder
* Copyright (c) 2009 Thilo Borgmann <thilo.borgmann _at_ googlemail.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation;
* version 2 of the License.
*
* 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
* General Public License for more details.
*
* You should have received a copy of the GNU 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
* MPEG-4 ALS decoder
* @author Thilo Borgmann <thilo.borgmann _at_ googlemail.com>
*/
//#define DEBUG
#include "avcodec.h"
#include "get_bits.h"
#include "unary.h"
#include "mpeg4audio.h"
#include "bytestream.h"
#include "bgmc.h"
#include "dsputil.h"
#include "libavutil/samplefmt.h"
#include "libavutil/crc.h"
#include <stdint.h>
/** Rice parameters and corresponding index offsets for decoding the
* indices of scaled PARCOR values. The table chosen 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}
};
/** Inter-channel weighting factors for multi-channel correlation.
* To be indexed by the Rice coded indices.
*/
static const int16_t mcc_weightings[] = {
204, 192, 179, 166, 153, 140, 128, 115,
102, 89, 76, 64, 51, 38, 25, 12,
0, -12, -25, -38, -51, -64, -76, -89,
-102, -115, -128, -140, -153, -166, -179, -192
};
/** Tail codes used in arithmetic coding using block Gilbert-Moore codes.
*/
static const uint8_t tail_code[16][6] = {
{ 74, 44, 25, 13, 7, 3},
{ 68, 42, 24, 13, 7, 3},
{ 58, 39, 23, 13, 7, 3},
{126, 70, 37, 19, 10, 5},
{132, 70, 37, 20, 10, 5},
{124, 70, 38, 20, 10, 5},
{120, 69, 37, 20, 11, 5},
{116, 67, 37, 20, 11, 5},
{108, 66, 36, 20, 10, 5},
{102, 62, 36, 20, 10, 5},
{ 88, 58, 34, 19, 10, 5},
{162, 89, 49, 25, 13, 7},
{156, 87, 49, 26, 14, 7},
{150, 86, 47, 26, 14, 7},
{142, 84, 47, 26, 14, 7},
{131, 79, 46, 26, 14, 7}
};
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 msb_first; ///< 1 = original CRC calculated on big-endian system, 0 = little-endian
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
int crc_enabled; ///< enable Cyclic Redundancy Checksum
} ALSSpecificConfig;
typedef struct {
int stop_flag;
int master_channel;
int time_diff_flag;
int time_diff_sign;
int time_diff_index;
int weighting[6];
} ALSChannelData;
typedef struct {
AVCodecContext *avctx;
ALSSpecificConfig sconf;
GetBitContext gb;
DSPContext dsp;
const AVCRC *crc_table;
uint32_t crc_org; ///< CRC value of the original input data
uint32_t crc; ///< CRC value calculated from decoded data
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
unsigned int s_max; ///< maximum Rice parameter allowed in entropy coding
uint8_t *bgmc_lut; ///< pointer at lookup tables used for BGMC
int *bgmc_lut_status; ///< pointer at lookup table status flags used for BGMC
int ltp_lag_length; ///< number of bits used for ltp lag value
int *const_block; ///< contains const_block flags for all channels
unsigned int *shift_lsbs; ///< contains shift_lsbs flags for all channels
unsigned int *opt_order; ///< contains opt_order flags for all channels
int *store_prev_samples; ///< contains store_prev_samples flags for all channels
int *use_ltp; ///< contains use_ltp flags for all channels
int *ltp_lag; ///< contains ltp lag values for all channels
int **ltp_gain; ///< gain values for ltp 5-tap filter for a channel
int *ltp_gain_buffer; ///< contains all gain values for ltp 5-tap filter
int32_t **quant_cof; ///< quantized parcor coefficients for a channel
int32_t *quant_cof_buffer; ///< contains all quantized parcor coefficients
int32_t **lpc_cof; ///< coefficients of the direct form prediction filter for a channel
int32_t *lpc_cof_buffer; ///< contains all coefficients of the direct form prediction filter
int32_t *lpc_cof_reversed_buffer; ///< temporary buffer to set up a reversed versio of lpc_cof_buffer
ALSChannelData **chan_data; ///< channel data for multi-channel correlation
ALSChannelData *chan_data_buffer; ///< contains channel data for all channels
int *reverted_channels; ///< stores a flag for each reverted channel
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
uint8_t *crc_buffer; ///< buffer of byte order corrected samples used for CRC check
} ALSDecContext;
typedef struct {
unsigned int block_length; ///< number of samples within the block
unsigned int ra_block; ///< if true, this is a random access block
int *const_block; ///< if true, this is a constant value block
int js_blocks; ///< true if this block contains a difference signal
unsigned int *shift_lsbs; ///< shift of values for this block
unsigned int *opt_order; ///< prediction order of this block
int *store_prev_samples;///< if true, carryover samples have to be stored
int *use_ltp; ///< if true, long-term prediction is used
int *ltp_lag; ///< lag value for long-term prediction
int *ltp_gain; ///< gain values for ltp 5-tap filter
int32_t *quant_cof; ///< quantized parcor coefficients
int32_t *lpc_cof; ///< coefficients of the direct form prediction
int32_t *raw_samples; ///< decoded raw samples / residuals for this block
int32_t *prev_raw_samples; ///< contains unshifted raw samples from the previous block
int32_t *raw_other; ///< decoded raw samples of the other channel of a channel pair
} ALSBlockData;
static av_cold void dprint_specific_config(ALSDecContext *ctx)
{
#ifdef DEBUG
AVCodecContext *avctx = ctx->avctx;
ALSSpecificConfig *sconf = &ctx->sconf;
av_dlog(avctx, "resolution = %i\n", sconf->resolution);
av_dlog(avctx, "floating = %i\n", sconf->floating);
av_dlog(avctx, "frame_length = %i\n", sconf->frame_length);
av_dlog(avctx, "ra_distance = %i\n", sconf->ra_distance);
av_dlog(avctx, "ra_flag = %i\n", sconf->ra_flag);
av_dlog(avctx, "adapt_order = %i\n", sconf->adapt_order);
av_dlog(avctx, "coef_table = %i\n", sconf->coef_table);
av_dlog(avctx, "long_term_prediction = %i\n", sconf->long_term_prediction);
av_dlog(avctx, "max_order = %i\n", sconf->max_order);
av_dlog(avctx, "block_switching = %i\n", sconf->block_switching);
av_dlog(avctx, "bgmc = %i\n", sconf->bgmc);
av_dlog(avctx, "sb_part = %i\n", sconf->sb_part);
av_dlog(avctx, "joint_stereo = %i\n", sconf->joint_stereo);
av_dlog(avctx, "mc_coding = %i\n", sconf->mc_coding);
av_dlog(avctx, "chan_config = %i\n", sconf->chan_config);
av_dlog(avctx, "chan_sort = %i\n", sconf->chan_sort);
av_dlog(avctx, "RLSLMS = %i\n", sconf->rlslms);
av_dlog(avctx, "chan_config_info = %i\n", sconf->chan_config_info);
#endif
}
/** Read 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;
MPEG4AudioConfig m4ac;
ALSSpecificConfig *sconf = &ctx->sconf;
AVCodecContext *avctx = ctx->avctx;
uint32_t als_id, header_size, trailer_size;
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);
sconf->msb_first = get_bits1(&gb);
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);
sconf->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;
// 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;
header_size = get_bits_long(&gb, 32);
trailer_size = get_bits_long(&gb, 32);
if (header_size == 0xFFFFFFFF)
header_size = 0;
if (trailer_size == 0xFFFFFFFF)
trailer_size = 0;
ht_size = ((int64_t)(header_size) + (int64_t)(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);
// initialize CRC calculation
if (sconf->crc_enabled) {
if (get_bits_left(&gb) < 32)
return -1;
if (avctx->error_recognition >= FF_ER_CAREFUL) {
ctx->crc_table = av_crc_get_table(AV_CRC_32_IEEE_LE);
ctx->crc = 0xFFFFFFFF;
ctx->crc_org = ~get_bits_long(&gb, 32);
} else
skip_bits_long(&gb, 32);
}
// no need to read the rest of ALSSpecificConfig (ra_unit_size & aux data)
dprint_specific_config(ctx);
return 0;
}
/** Check 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->rlslms, "Adaptive RLS-LMS prediction", -1);
MISSING_ERR(sconf->chan_sort, "Channel sorting", 0);
return error;
}
/** Parse 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)++;
}
}
/** Read and decode 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;
}
/** Convert 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];
}
/** Read block switching field if necessary and set actual block sizes.
* Also assure 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];
}
}
}
/** Read the block data for a constant block
*/
static void read_const_block_data(ALSDecContext *ctx, ALSBlockData *bd)
{
ALSSpecificConfig *sconf = &ctx->sconf;
AVCodecContext *avctx = ctx->avctx;
GetBitContext *gb = &ctx->gb;
*bd->raw_samples = 0;
*bd->const_block = get_bits1(gb); // 1 = constant value, 0 = zero block (silence)
bd->js_blocks = get_bits1(gb);
// skip 5 reserved bits
skip_bits(gb, 5);
if (*bd->const_block) {
unsigned int const_val_bits = sconf->floating ? 24 : avctx->bits_per_raw_sample;
*bd->raw_samples = get_sbits_long(gb, const_val_bits);
}
// ensure constant block decoding by reusing this field
*bd->const_block = 1;
}
/** Decode the block data for a constant block
*/
static void decode_const_block_data(ALSDecContext *ctx, ALSBlockData *bd)
{
int smp = bd->block_length - 1;
int32_t val = *bd->raw_samples;
int32_t *dst = bd->raw_samples + 1;
// write raw samples into buffer
for (; smp; smp--)
*dst++ = val;
}
/** Read the block data for a non-constant block
*/
static int read_var_block_data(ALSDecContext *ctx, ALSBlockData *bd)
{
ALSSpecificConfig *sconf = &ctx->sconf;
AVCodecContext *avctx = ctx->avctx;
GetBitContext *gb = &ctx->gb;
unsigned int k;
unsigned int s[8];
unsigned int sx[8];
unsigned int sub_blocks, log2_sub_blocks, sb_length;
unsigned int start = 0;
unsigned int opt_order;
int sb;
int32_t *quant_cof = bd->quant_cof;
int32_t *current_res;
// ensure variable block decoding by reusing this field
*bd->const_block = 0;
*bd->opt_order = 1;
bd->js_blocks = get_bits1(gb);
opt_order = *bd->opt_order;
// 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 (bd->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 = bd->block_length >> log2_sub_blocks;
if (sconf->bgmc) {
s[0] = get_bits(gb, 8 + (sconf->resolution > 1));
for (k = 1; k < sub_blocks; k++)
s[k] = s[k - 1] + decode_rice(gb, 2);
for (k = 0; k < sub_blocks; k++) {
sx[k] = s[k] & 0x0F;
s [k] >>= 4;
}
} 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))
*bd->shift_lsbs = get_bits(gb, 4) + 1;
*bd->store_prev_samples = (bd->js_blocks && bd->raw_other) || *bd->shift_lsbs;
if (!sconf->rlslms) {
if (sconf->adapt_order) {
int opt_order_length = av_ceil_log2(av_clip((bd->block_length >> 3) - 1,
2, sconf->max_order + 1));
*bd->opt_order = get_bits(gb, opt_order_length);
} else {
*bd->opt_order = sconf->max_order;
}
opt_order = *bd->opt_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) {
*bd->use_ltp = get_bits1(gb);
if (*bd->use_ltp) {
int r, c;
bd->ltp_gain[0] = decode_rice(gb, 1) << 3;
bd->ltp_gain[1] = decode_rice(gb, 2) << 3;
r = get_unary(gb, 0, 4);
c = get_bits(gb, 2);
bd->ltp_gain[2] = ltp_gain_values[r][c];
bd->ltp_gain[3] = decode_rice(gb, 2) << 3;
bd->ltp_gain[4] = decode_rice(gb, 1) << 3;
*bd->ltp_lag = get_bits(gb, ctx->ltp_lag_length);
*bd->ltp_lag += FFMAX(4, opt_order + 1);
}
}
// read first value and residuals in case of a random access block
if (bd->ra_block) {
if (opt_order)
bd->raw_samples[0] = decode_rice(gb, avctx->bits_per_raw_sample - 4);
if (opt_order > 1)
bd->raw_samples[1] = decode_rice(gb, FFMIN(s[0] + 3, ctx->s_max));
if (opt_order > 2)
bd->raw_samples[2] = decode_rice(gb, FFMIN(s[0] + 1, ctx->s_max));
start = FFMIN(opt_order, 3);
}
// read all residuals
if (sconf->bgmc) {
int delta[8];
unsigned int k [8];
unsigned int b = av_clip((av_ceil_log2(bd->block_length) - 3) >> 1, 0, 5);
unsigned int i = start;
// read most significant bits
unsigned int high;
unsigned int low;
unsigned int value;
ff_bgmc_decode_init(gb, &high, &low, &value);
current_res = bd->raw_samples + start;
for (sb = 0; sb < sub_blocks; sb++, i = 0) {
k [sb] = s[sb] > b ? s[sb] - b : 0;
delta[sb] = 5 - s[sb] + k[sb];
ff_bgmc_decode(gb, sb_length, current_res,
delta[sb], sx[sb], &high, &low, &value, ctx->bgmc_lut, ctx->bgmc_lut_status);
current_res += sb_length;
}
ff_bgmc_decode_end(gb);
// read least significant bits and tails
i = start;
current_res = bd->raw_samples + start;
for (sb = 0; sb < sub_blocks; sb++, i = 0) {
unsigned int cur_tail_code = tail_code[sx[sb]][delta[sb]];
unsigned int cur_k = k[sb];
unsigned int cur_s = s[sb];
for (; i < sb_length; i++) {
int32_t res = *current_res;
if (res == cur_tail_code) {
unsigned int max_msb = (2 + (sx[sb] > 2) + (sx[sb] > 10))
<< (5 - delta[sb]);
res = decode_rice(gb, cur_s);
if (res >= 0) {
res += (max_msb ) << cur_k;
} else {
res -= (max_msb - 1) << cur_k;
}
} else {
if (res > cur_tail_code)
res--;
if (res & 1)
res = -res;
res >>= 1;
if (cur_k) {
res <<= cur_k;
res |= get_bits_long(gb, cur_k);
}
}
*current_res++ = res;
}
}
} else {
current_res = bd->raw_samples + start;
for (sb = 0; sb < sub_blocks; sb++, start = 0)
for (; start < sb_length; start++)
*current_res++ = decode_rice(gb, s[sb]);
}
if (!sconf->mc_coding || ctx->js_switch)
align_get_bits(gb);
return 0;
}
/** Decode the block data for a non-constant block
*/
static int decode_var_block_data(ALSDecContext *ctx, ALSBlockData *bd)
{
ALSSpecificConfig *sconf = &ctx->sconf;
unsigned int block_length = bd->block_length;
unsigned int smp = 0;
unsigned int k;
int opt_order = *bd->opt_order;
int sb;
int64_t y;
int32_t *quant_cof = bd->quant_cof;
int32_t *lpc_cof = bd->lpc_cof;
int32_t *raw_samples = bd->raw_samples;
int32_t *raw_samples_end = bd->raw_samples + bd->block_length;
int32_t *lpc_cof_reversed = ctx->lpc_cof_reversed_buffer;
// reverse long-term prediction
if (*bd->use_ltp) {
int ltp_smp;
for (ltp_smp = FFMAX(*bd->ltp_lag - 2, 0); ltp_smp < block_length; ltp_smp++) {
int center = ltp_smp - *bd->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(bd->ltp_gain[tab], raw_samples[base]);
raw_samples[ltp_smp] += y >> 7;
}
}
// reconstruct all samples from residuals
if (bd->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[-(sb + 1)]);
*raw_samples++ -= 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 (*bd->store_prev_samples)
memcpy(bd->prev_raw_samples, raw_samples - sconf->max_order,
sizeof(*bd->prev_raw_samples) * sconf->max_order);
// reconstruct difference signal for prediction (joint-stereo)
if (bd->js_blocks && bd->raw_other) {
int32_t *left, *right;
if (bd->raw_other > raw_samples) { // D = R - L
left = raw_samples;
right = bd->raw_other;
} else { // D = R - L
left = bd->raw_other;
right = raw_samples;
}
for (sb = -1; sb >= -sconf->max_order; sb--)
raw_samples[sb] = right[sb] - left[sb];
}
// reconstruct shifted signal
if (*bd->shift_lsbs)
for (sb = -1; sb >= -sconf->max_order; sb--)
raw_samples[sb] >>= *bd->shift_lsbs;
}
// reverse linear prediction coefficients for efficiency
lpc_cof = lpc_cof + opt_order;
for (sb = 0; sb < opt_order; sb++)
lpc_cof_reversed[sb] = lpc_cof[-(sb + 1)];
// reconstruct raw samples
raw_samples = bd->raw_samples + smp;
lpc_cof = lpc_cof_reversed + opt_order;
for (; raw_samples < raw_samples_end; raw_samples++) {
y = 1 << 19;
for (sb = -opt_order; sb < 0; sb++)
y += MUL64(lpc_cof[sb], raw_samples[sb]);
*raw_samples -= y >> 20;
}
raw_samples = bd->raw_samples;
// restore previous samples in case that they have been altered
if (*bd->store_prev_samples)
memcpy(raw_samples - sconf->max_order, bd->prev_raw_samples,
sizeof(*raw_samples) * sconf->max_order);
return 0;
}
/** Read the block data.
*/
static int read_block(ALSDecContext *ctx, ALSBlockData *bd)
{
GetBitContext *gb = &ctx->gb;
*bd->shift_lsbs = 0;
// read block type flag and read the samples accordingly
if (get_bits1(gb)) {
if (read_var_block_data(ctx, bd))
return -1;
} else {
read_const_block_data(ctx, bd);
}
return 0;
}
/** Decode the block data.
*/
static int decode_block(ALSDecContext *ctx, ALSBlockData *bd)
{
unsigned int smp;
// read block type flag and read the samples accordingly
if (*bd->const_block)
decode_const_block_data(ctx, bd);
else if (decode_var_block_data(ctx, bd))
return -1;
// TODO: read RLSLMS extension data
if (*bd->shift_lsbs)
for (smp = 0; smp < bd->block_length; smp++)
bd->raw_samples[smp] <<= *bd->shift_lsbs;
return 0;
}
/** Read and decode block data successively.
*/
static int read_decode_block(ALSDecContext *ctx, ALSBlockData *bd)
{
int ret;
ret = read_block(ctx, bd);
if (ret)
return ret;
ret = decode_block(ctx, bd);