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/*
* ALAC (Apple Lossless Audio Codec) decoder
* Copyright (c) 2005 David Hammerton
* All rights reserved.
*
* This is the actual decoder.
*
* http://crazney.net/programs/itunes/alac.html
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
*/
static const int host_bigendian = 0;
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef _WIN32
#include "stdint_win.h"
#else
#include <stdint.h>
#endif
#include "alac.h"
#define _Swap32(v) do { \
v = (((v) & 0x000000FF) << 0x18) | \
(((v) & 0x0000FF00) << 0x08) | \
(((v) & 0x00FF0000) >> 0x08) | \
(((v) & 0xFF000000) >> 0x18); } while(0)
#define _Swap16(v) do { \
v = (((v) & 0x00FF) << 0x08) | \
(((v) & 0xFF00) >> 0x08); } while (0)
struct {signed int x:24;} se_struct_24;
#define SignExtend24(val) (se_struct_24.x = val)
void allocate_buffers(alac_file *alac)
{
alac->predicterror_buffer_a = malloc(alac->setinfo_max_samples_per_frame * 4);
alac->predicterror_buffer_b = malloc(alac->setinfo_max_samples_per_frame * 4);
alac->outputsamples_buffer_a = malloc(alac->setinfo_max_samples_per_frame * 4);
alac->outputsamples_buffer_b = malloc(alac->setinfo_max_samples_per_frame * 4);
alac->uncompressed_bytes_buffer_a = malloc(alac->setinfo_max_samples_per_frame * 4);
alac->uncompressed_bytes_buffer_b = malloc(alac->setinfo_max_samples_per_frame * 4);
}
void alac_set_info(alac_file *alac, char *inputbuffer)
{
char *ptr = inputbuffer;
ptr += 4; /* size */
ptr += 4; /* frma */
ptr += 4; /* alac */
ptr += 4; /* size */
ptr += 4; /* alac */
ptr += 4; /* 0 ? */
alac->setinfo_max_samples_per_frame = *(uint32_t*)ptr; /* buffer size / 2 ? */
if (!host_bigendian)
_Swap32(alac->setinfo_max_samples_per_frame);
ptr += 4;
alac->setinfo_7a = *(uint8_t*)ptr;
ptr += 1;
alac->setinfo_sample_size = *(uint8_t*)ptr;
ptr += 1;
alac->setinfo_rice_historymult = *(uint8_t*)ptr;
ptr += 1;
alac->setinfo_rice_initialhistory = *(uint8_t*)ptr;
ptr += 1;
alac->setinfo_rice_kmodifier = *(uint8_t*)ptr;
ptr += 1;
alac->setinfo_7f = *(uint8_t*)ptr;
ptr += 1;
alac->setinfo_80 = *(uint16_t*)ptr;
if (!host_bigendian)
_Swap16(alac->setinfo_80);
ptr += 2;
alac->setinfo_82 = *(uint32_t*)ptr;
if (!host_bigendian)
_Swap32(alac->setinfo_82);
ptr += 4;
alac->setinfo_86 = *(uint32_t*)ptr;
if (!host_bigendian)
_Swap32(alac->setinfo_86);
ptr += 4;
alac->setinfo_8a_rate = *(uint32_t*)ptr;
if (!host_bigendian)
_Swap32(alac->setinfo_8a_rate);
ptr += 4;
allocate_buffers(alac);
}
/* stream reading */
/* supports reading 1 to 16 bits, in big endian format */
static uint32_t readbits_16(alac_file *alac, int bits)
{
uint32_t result;
int new_accumulator;
result = (alac->input_buffer[0] << 16) |
(alac->input_buffer[1] << 8) |
(alac->input_buffer[2]);
/* shift left by the number of bits we've already read,
* so that the top 'n' bits of the 24 bits we read will
* be the return bits */
result = result << alac->input_buffer_bitaccumulator;
result = result & 0x00ffffff;
/* and then only want the top 'n' bits from that, where
* n is 'bits' */
result = result >> (24 - bits);
new_accumulator = (alac->input_buffer_bitaccumulator + bits);
/* increase the buffer pointer if we've read over n bytes. */
alac->input_buffer += (new_accumulator >> 3);
/* and the remainder goes back into the bit accumulator */
alac->input_buffer_bitaccumulator = (new_accumulator & 7);
return result;
}
/* supports reading 1 to 32 bits, in big endian format */
static uint32_t readbits(alac_file *alac, int bits)
{
int32_t result = 0;
if (bits > 16)
{
bits -= 16;
result = readbits_16(alac, 16) << bits;
}
result |= readbits_16(alac, bits);
return result;
}
/* reads a single bit */
static int readbit(alac_file *alac)
{
int result;
int new_accumulator;
result = alac->input_buffer[0];
result = result << alac->input_buffer_bitaccumulator;
result = result >> 7 & 1;
new_accumulator = (alac->input_buffer_bitaccumulator + 1);
alac->input_buffer += (new_accumulator / 8);
alac->input_buffer_bitaccumulator = (new_accumulator % 8);
return result;
}
static void unreadbits(alac_file *alac, int bits)
{
int new_accumulator = (alac->input_buffer_bitaccumulator - bits);
alac->input_buffer += (new_accumulator >> 3);
alac->input_buffer_bitaccumulator = (new_accumulator & 7);
if (alac->input_buffer_bitaccumulator < 0)
alac->input_buffer_bitaccumulator *= -1;
}
/* various implementations of count_leading_zero:
* the first one is the original one, the simplest and most
* obvious for what it's doing. never use this.
* then there are the asm ones. fill in as necessary
* and finally an unrolled and optimised c version
* to fall back to
*/
#if 0
/* hideously inefficient. could use a bitmask search,
* alternatively bsr on x86,
*/
static int count_leading_zeros(int32_t input)
{
int i = 0;
while (!(0x80000000 & input) && i < 32)
{
i++;
input = input << 1;
}
return i;
}
#elif defined(__GNUC__) && (defined(_X86) || defined(__i386) || defined(i386))
/* for some reason the unrolled version (below) is
* actually faster than this. yay intel!
*/
static int count_leading_zeros(int input)
{
int output = 0;
if (!input) return 32;
__asm("bsr %1, %0\n"
: "=r" (output)
: "r" (input));
return (0x1f - output);
}
#elif defined(_MSC_VER) && defined(_M_IX86)
static int count_leading_zeros(int input)
{
int output = 0;
if (!input) return 32;
__asm
{
mov eax, input;
mov edx, 0x1f;
bsr ecx, eax;
sub edx, ecx;
mov output, edx;
}
return output;
}
#else
#warning using generic count leading zeroes. You may wish to write one for your CPU / compiler
static int count_leading_zeros(int input)
{
int output = 0;
int curbyte = 0;
curbyte = input >> 24;
if (curbyte) goto found;
output += 8;
curbyte = input >> 16;
if (curbyte & 0xff) goto found;
output += 8;
curbyte = input >> 8;
if (curbyte & 0xff) goto found;
output += 8;
curbyte = input;
if (curbyte & 0xff) goto found;
output += 8;
return output;
found:
if (!(curbyte & 0xf0))
{
output += 4;
}
else
curbyte >>= 4;
if (curbyte & 0x8)
return output;
if (curbyte & 0x4)
return output + 1;
if (curbyte & 0x2)
return output + 2;
if (curbyte & 0x1)
return output + 3;
/* shouldn't get here: */
return output + 4;
}
#endif
#define RICE_THRESHOLD 8 // maximum number of bits for a rice prefix.
int32_t entropy_decode_value(alac_file* alac,
int readSampleSize,
int k,
int rice_kmodifier_mask)
{
int32_t x = 0; // decoded value
// read x, number of 1s before 0 represent the rice value.
while (x <= RICE_THRESHOLD && readbit(alac))
{
x++;
}
if (x > RICE_THRESHOLD)
{
// read the number from the bit stream (raw value)
int32_t value;
value = readbits(alac, readSampleSize);
// mask value
value &= (((uint32_t)0xffffffff) >> (32 - readSampleSize));
x = value;
}
else
{
if (k != 1)
{
int extraBits = readbits(alac, k);
// x = x * (2^k - 1)
x *= (((1 << k) - 1) & rice_kmodifier_mask);
if (extraBits > 1)
x += extraBits - 1;
else
unreadbits(alac, 1);
}
}
return x;
}
void entropy_rice_decode(alac_file* alac,
int32_t* outputBuffer,
int outputSize,
int readSampleSize,
int rice_initialhistory,
int rice_kmodifier,
int rice_historymult,
int rice_kmodifier_mask)
{
int outputCount;
int history = rice_initialhistory;
int signModifier = 0;
for (outputCount = 0; outputCount < outputSize; outputCount++)
{
int32_t decodedValue;
int32_t finalValue;
int32_t k;
k = 31 - rice_kmodifier - count_leading_zeros((history >> 9) + 3);
if (k < 0) k += rice_kmodifier;
else k = rice_kmodifier;
// note: don't use rice_kmodifier_mask here (set mask to 0xFFFFFFFF)
decodedValue = entropy_decode_value(alac, readSampleSize, k, 0xFFFFFFFF);
decodedValue += signModifier;
finalValue = (decodedValue + 1) / 2; // inc by 1 and shift out sign bit
if (decodedValue & 1) // the sign is stored in the low bit
finalValue *= -1;
outputBuffer[outputCount] = finalValue;
signModifier = 0;
// update history
history += (decodedValue * rice_historymult)
- ((history * rice_historymult) >> 9);
if (decodedValue > 0xFFFF)
history = 0xFFFF;
// special case, for compressed blocks of 0
if ((history < 128) && (outputCount + 1 < outputSize))
{
int32_t blockSize;
signModifier = 1;
k = count_leading_zeros(history) + ((history + 16) / 64) - 24;
// note: blockSize is always 16bit
blockSize = entropy_decode_value(alac, 16, k, rice_kmodifier_mask);
// got blockSize 0s
if (blockSize > 0)
{
memset(&outputBuffer[outputCount + 1], 0, blockSize * sizeof(*outputBuffer));
outputCount += blockSize;
}
if (blockSize > 0xFFFF)
signModifier = 0;
history = 0;
}
}
}
#define SIGN_EXTENDED32(val, bits) ((val << (32 - bits)) >> (32 - bits))
#define SIGN_ONLY(v) \
((v < 0) ? (-1) : \
((v > 0) ? (1) : \
(0)))
static void predictor_decompress_fir_adapt(int32_t *error_buffer,
int32_t *buffer_out,
int output_size,
int readsamplesize,
int16_t *predictor_coef_table,
int predictor_coef_num,
int predictor_quantitization)
{
int i;
/* first sample always copies */
*buffer_out = *error_buffer;
if (!predictor_coef_num)
{
if (output_size <= 1) return;
memcpy(buffer_out+1, error_buffer+1, (output_size-1) * 4);
return;
}
if (predictor_coef_num == 0x1f) /* 11111 - max value of predictor_coef_num */
{ /* second-best case scenario for fir decompression,
* error describes a small difference from the previous sample only
*/
if (output_size <= 1) return;
for (i = 0; i < output_size - 1; i++)
{
int32_t prev_value;
int32_t error_value;
prev_value = buffer_out[i];
error_value = error_buffer[i+1];
buffer_out[i+1] = SIGN_EXTENDED32((prev_value + error_value), readsamplesize);
}
return;
}
/* read warm-up samples */
if (predictor_coef_num > 0)
{
int i;
for (i = 0; i < predictor_coef_num; i++)
{
int32_t val;
val = buffer_out[i] + error_buffer[i+1];
val = SIGN_EXTENDED32(val, readsamplesize);
buffer_out[i+1] = val;
}
}
#if 0
/* 4 and 8 are very common cases (the only ones i've seen). these
* should be unrolled and optimised
*/
if (predictor_coef_num == 4)
{
/* FIXME: optimised general case */
return;
}
if (predictor_coef_table == 8)
{
/* FIXME: optimised general case */
return;
}
#endif
/* general case */
if (predictor_coef_num > 0)
{
for (i = predictor_coef_num + 1;
i < output_size;
i++)
{
int j;
int sum = 0;
int outval;
int error_val = error_buffer[i];
for (j = 0; j < predictor_coef_num; j++)
{
sum += (buffer_out[predictor_coef_num-j] - buffer_out[0]) *
predictor_coef_table[j];
}
outval = (1 << (predictor_quantitization-1)) + sum;
outval = outval >> predictor_quantitization;
outval = outval + buffer_out[0] + error_val;
outval = SIGN_EXTENDED32(outval, readsamplesize);
buffer_out[predictor_coef_num+1] = outval;
if (error_val > 0)
{
int predictor_num = predictor_coef_num - 1;
while (predictor_num >= 0 && error_val > 0)
{
int val = buffer_out[0] - buffer_out[predictor_coef_num - predictor_num];
int sign = SIGN_ONLY(val);
predictor_coef_table[predictor_num] -= sign;
val *= sign; /* absolute value */
error_val -= ((val >> predictor_quantitization) *
(predictor_coef_num - predictor_num));
predictor_num--;
}
}
else if (error_val < 0)
{
int predictor_num = predictor_coef_num - 1;
while (predictor_num >= 0 && error_val < 0)
{
int val = buffer_out[0] - buffer_out[predictor_coef_num - predictor_num];
int sign = - SIGN_ONLY(val);
predictor_coef_table[predictor_num] -= sign;
val *= sign; /* neg value */
error_val -= ((val >> predictor_quantitization) *
(predictor_coef_num - predictor_num));
predictor_num--;
}
}
buffer_out++;
}
}
}
void deinterlace_16(int32_t *buffer_a, int32_t *buffer_b,
int16_t *buffer_out,
int numchannels, int numsamples,
uint8_t interlacing_shift,
uint8_t interlacing_leftweight)
{
int i;
if (numsamples <= 0) return;
/* weighted interlacing */
if (interlacing_leftweight)
{
for (i = 0; i < numsamples; i++)
{
int32_t difference, midright;
int16_t left;
int16_t right;
midright = buffer_a[i];
difference = buffer_b[i];
right = midright - ((difference * interlacing_leftweight) >> interlacing_shift);
left = right + difference;
/* output is always little endian */
if (host_bigendian)
{
_Swap16(left);
_Swap16(right);
}
buffer_out[i*numchannels] = left;
buffer_out[i*numchannels + 1] = right;
}
return;
}
/* otherwise basic interlacing took place */
for (i = 0; i < numsamples; i++)
{
int16_t left, right;
left = buffer_a[i];
right = buffer_b[i];
/* output is always little endian */
if (host_bigendian)
{
_Swap16(left);
_Swap16(right);
}
buffer_out[i*numchannels] = left;
buffer_out[i*numchannels + 1] = right;
}
}
void deinterlace_24(int32_t *buffer_a, int32_t *buffer_b,
int uncompressed_bytes,
int32_t *uncompressed_bytes_buffer_a, int32_t *uncompressed_bytes_buffer_b,
void *buffer_out,
int numchannels, int numsamples,
uint8_t interlacing_shift,
uint8_t interlacing_leftweight)
{
int i;
if (numsamples <= 0) return;
/* weighted interlacing */
if (interlacing_leftweight)
{
for (i = 0; i < numsamples; i++)
{
int32_t difference, midright;
int32_t left;
int32_t right;
midright = buffer_a[i];
difference = buffer_b[i];
right = midright - ((difference * interlacing_leftweight) >> interlacing_shift);
left = right + difference;
if (uncompressed_bytes)
{
uint32_t mask = ~(0xFFFFFFFF << (uncompressed_bytes * 8));
left <<= (uncompressed_bytes * 8);
right <<= (uncompressed_bytes * 8);
left |= uncompressed_bytes_buffer_a[i] & mask;
right |= uncompressed_bytes_buffer_b[i] & mask;
}
((uint8_t*)buffer_out)[i * numchannels * 3] = (left) & 0xFF;
((uint8_t*)buffer_out)[i * numchannels * 3 + 1] = (left >> 8) & 0xFF;
((uint8_t*)buffer_out)[i * numchannels * 3 + 2] = (left >> 16) & 0xFF;
((uint8_t*)buffer_out)[i * numchannels * 3 + 3] = (right) & 0xFF;
((uint8_t*)buffer_out)[i * numchannels * 3 + 4] = (right >> 8) & 0xFF;
((uint8_t*)buffer_out)[i * numchannels * 3 + 5] = (right >> 16) & 0xFF;
}
return;
}
/* otherwise basic interlacing took place */
for (i = 0; i < numsamples; i++)
{
int32_t left, right;
left = buffer_a[i];
right = buffer_b[i];
if (uncompressed_bytes)
{
uint32_t mask = ~(0xFFFFFFFF << (uncompressed_bytes * 8));
left <<= (uncompressed_bytes * 8);
right <<= (uncompressed_bytes * 8);
left |= uncompressed_bytes_buffer_a[i] & mask;
right |= uncompressed_bytes_buffer_b[i] & mask;
}
((uint8_t*)buffer_out)[i * numchannels * 3] = (left) & 0xFF;
((uint8_t*)buffer_out)[i * numchannels * 3 + 1] = (left >> 8) & 0xFF;
((uint8_t*)buffer_out)[i * numchannels * 3 + 2] = (left >> 16) & 0xFF;
((uint8_t*)buffer_out)[i * numchannels * 3 + 3] = (right) & 0xFF;
((uint8_t*)buffer_out)[i * numchannels * 3 + 4] = (right >> 8) & 0xFF;
((uint8_t*)buffer_out)[i * numchannels * 3 + 5] = (right >> 16) & 0xFF;
}
}
void decode_frame(alac_file *alac,
unsigned char *inbuffer,
void *outbuffer, int *outputsize)
{
int channels;
int32_t outputsamples = alac->setinfo_max_samples_per_frame;
/* setup the stream */
alac->input_buffer = inbuffer;
alac->input_buffer_bitaccumulator = 0;
channels = readbits(alac, 3);
*outputsize = outputsamples * alac->bytespersample;
switch(channels)
{
case 0: /* 1 channel */
{
int hassize;
int isnotcompressed;
int readsamplesize;
int uncompressed_bytes;
int ricemodifier;
/* 2^result = something to do with output waiting.
* perhaps matters if we read > 1 frame in a pass?
*/
readbits(alac, 4);
readbits(alac, 12); /* unknown, skip 12 bits */
hassize = readbits(alac, 1); /* the output sample size is stored soon */
uncompressed_bytes = readbits(alac, 2); /* number of bytes in the (compressed) stream that are not compressed */
isnotcompressed = readbits(alac, 1); /* whether the frame is compressed */
if (hassize)
{
/* now read the number of samples,
* as a 32bit integer */
outputsamples = readbits(alac, 32);
*outputsize = outputsamples * alac->bytespersample;
}
readsamplesize = alac->setinfo_sample_size - (uncompressed_bytes * 8);
if (!isnotcompressed)
{ /* so it is compressed */
int16_t predictor_coef_table[32];
int predictor_coef_num;
int prediction_type;
int prediction_quantitization;
int i;
/* skip 16 bits, not sure what they are. seem to be used in
* two channel case */
readbits(alac, 8);
readbits(alac, 8);
prediction_type = readbits(alac, 4);
prediction_quantitization = readbits(alac, 4);
ricemodifier = readbits(alac, 3);
predictor_coef_num = readbits(alac, 5);
/* read the predictor table */
for (i = 0; i < predictor_coef_num; i++)
{
predictor_coef_table[i] = (int16_t)readbits(alac, 16);
}
if (uncompressed_bytes)
{
int i;
for (i = 0; i < outputsamples; i++)
{
alac->uncompressed_bytes_buffer_a[i] = readbits(alac, uncompressed_bytes * 8);
}
}
entropy_rice_decode(alac,
alac->predicterror_buffer_a,
outputsamples,
readsamplesize,
alac->setinfo_rice_initialhistory,
alac->setinfo_rice_kmodifier,
ricemodifier * alac->setinfo_rice_historymult / 4,
(1 << alac->setinfo_rice_kmodifier) - 1);
if (prediction_type == 0)
{ /* adaptive fir */
predictor_decompress_fir_adapt(alac->predicterror_buffer_a,
alac->outputsamples_buffer_a,
outputsamples,
readsamplesize,
predictor_coef_table,
predictor_coef_num,
prediction_quantitization);
}
else
{
fprintf(stderr, "FIXME: unhandled predicition type: %i\n", prediction_type);
/* i think the only other prediction type (or perhaps this is just a
* boolean?) runs adaptive fir twice.. like:
* predictor_decompress_fir_adapt(predictor_error, tempout, ...)
* predictor_decompress_fir_adapt(predictor_error, outputsamples ...)
* little strange..
*/
}
}
else
{ /* not compressed, easy case */
if (alac->setinfo_sample_size <= 16)
{
int i;
for (i = 0; i < outputsamples; i++)
{
int32_t audiobits = readbits(alac, alac->setinfo_sample_size);
audiobits = SIGN_EXTENDED32(audiobits, alac->setinfo_sample_size);
alac->outputsamples_buffer_a[i] = audiobits;
}
}
else
{
int i;
for (i = 0; i < outputsamples; i++)
{
int32_t audiobits;
audiobits = readbits(alac, 16);
/* special case of sign extension..
* as we'll be ORing the low 16bits into this */
audiobits = audiobits << (alac->setinfo_sample_size - 16);
audiobits |= readbits(alac, alac->setinfo_sample_size - 16);
audiobits = SignExtend24(audiobits);
alac->outputsamples_buffer_a[i] = audiobits;
}
}
uncompressed_bytes = 0; // always 0 for uncompressed
}
switch(alac->setinfo_sample_size)
{
case 16:
{
int i;
for (i = 0; i < outputsamples; i++)
{
int16_t sample = alac->outputsamples_buffer_a[i];
if (host_bigendian)
_Swap16(sample);
((int16_t*)outbuffer)[i * alac->numchannels] = sample;
}
break;
}
case 24:
{
int i;
for (i = 0; i < outputsamples; i++)
{
int32_t sample = alac->outputsamples_buffer_a[i];
if (uncompressed_bytes)
{
uint32_t mask;
sample = sample << (uncompressed_bytes * 8);
mask = ~(0xFFFFFFFF << (uncompressed_bytes * 8));
sample |= alac->uncompressed_bytes_buffer_a[i] & mask;
}
((uint8_t*)outbuffer)[i * alac->numchannels * 3] = (sample) & 0xFF;
((uint8_t*)outbuffer)[i * alac->numchannels * 3 + 1] = (sample >> 8) & 0xFF;
((uint8_t*)outbuffer)[i * alac->numchannels * 3 + 2] = (sample >> 16) & 0xFF;
}
break;
}
case 20:
case 32:
fprintf(stderr, "FIXME: unimplemented sample size %i\n", alac->setinfo_sample_size);
break;
default:
break;
}
break;
}
case 1: /* 2 channels */
{
int hassize;
int isnotcompressed;
int readsamplesize;
int uncompressed_bytes;
uint8_t interlacing_shift;
uint8_t interlacing_leftweight;
/* 2^result = something to do with output waiting.
* perhaps matters if we read > 1 frame in a pass?
*/
readbits(alac, 4);
readbits(alac, 12); /* unknown, skip 12 bits */
hassize = readbits(alac, 1); /* the output sample size is stored soon */
uncompressed_bytes = readbits(alac, 2); /* the number of bytes in the (compressed) stream that are not compressed */
isnotcompressed = readbits(alac, 1); /* whether the frame is compressed */
if (hassize)
{
/* now read the number of samples,
* as a 32bit integer */
outputsamples = readbits(alac, 32);
*outputsize = outputsamples * alac->bytespersample;
}
readsamplesize = alac->setinfo_sample_size - (uncompressed_bytes * 8) + 1;
if (!isnotcompressed)
{ /* compressed */
int16_t predictor_coef_table_a[32];
int predictor_coef_num_a;
int prediction_type_a;
int prediction_quantitization_a;
int ricemodifier_a;
int16_t predictor_coef_table_b[32];
int predictor_coef_num_b;
int prediction_type_b;
int prediction_quantitization_b;
int ricemodifier_b;
int i;
interlacing_shift = readbits(alac, 8);
interlacing_leftweight = readbits(alac, 8);
/******** channel 1 ***********/
prediction_type_a = readbits(alac, 4);
prediction_quantitization_a = readbits(alac, 4);
ricemodifier_a = readbits(alac, 3);
predictor_coef_num_a = readbits(alac, 5);
/* read the predictor table */
for (i = 0; i < predictor_coef_num_a; i++)
{
predictor_coef_table_a[i] = (int16_t)readbits(alac, 16);
}
/******** channel 2 *********/
prediction_type_b = readbits(alac, 4);
prediction_quantitization_b = readbits(alac, 4);
ricemodifier_b = readbits(alac, 3);
predictor_coef_num_b = readbits(alac, 5);
/* read the predictor table */
for (i = 0; i < predictor_coef_num_b; i++)
{
predictor_coef_table_b[i] = (int16_t)readbits(alac, 16);
}
/*********************/
if (uncompressed_bytes)
{ /* see mono case */
int i;
for (i = 0; i < outputsamples; i++)
{
alac->uncompressed_bytes_buffer_a[i] = readbits(alac, uncompressed_bytes * 8);
alac->uncompressed_bytes_buffer_b[i] = readbits(alac, uncompressed_bytes * 8);
}
}
/* channel 1 */
entropy_rice_decode(alac,
alac->predicterror_buffer_a,
outputsamples,
readsamplesize,
alac->setinfo_rice_initialhistory,
alac->setinfo_rice_kmodifier,
ricemodifier_a * alac->setinfo_rice_historymult / 4,
(1 << alac->setinfo_rice_kmodifier) - 1);
if (prediction_type_a == 0)
{ /* adaptive fir */
predictor_decompress_fir_adapt(alac->predicterror_buffer_a,
alac->outputsamples_buffer_a,
outputsamples,
readsamplesize,
predictor_coef_table_a,
predictor_coef_num_a,
prediction_quantitization_a);
}
else
{ /* see mono case */
fprintf(stderr, "FIXME: unhandled predicition type: %i\n", prediction_type_a);
}
/* channel 2 */
entropy_rice_decode(alac,
alac->predicterror_buffer_b,
outputsamples,
readsamplesize,
alac->setinfo_rice_initialhistory,
alac->setinfo_rice_kmodifier,
ricemodifier_b * alac->setinfo_rice_historymult / 4,
(1 << alac->setinfo_rice_kmodifier) - 1);
if (prediction_type_b == 0)
{ /* adaptive fir */
predictor_decompress_fir_adapt(alac->predicterror_buffer_b,
alac->outputsamples_buffer_b,
outputsamples,
readsamplesize,
predictor_coef_table_b,
predictor_coef_num_b,
prediction_quantitization_b);
}
else
{
fprintf(stderr, "FIXME: unhandled predicition type: %i\n", prediction_type_b);
}
}
else
{ /* not compressed, easy case */
if (alac->setinfo_sample_size <= 16)
{
int i;
for (i = 0; i < outputsamples; i++)
{
int32_t audiobits_a, audiobits_b;
audiobits_a = readbits(alac, alac->setinfo_sample_size);
audiobits_b = readbits(alac, alac->setinfo_sample_size);
audiobits_a = SIGN_EXTENDED32(audiobits_a, alac->setinfo_sample_size);
audiobits_b = SIGN_EXTENDED32(audiobits_b, alac->setinfo_sample_size);
alac->outputsamples_buffer_a[i] = audiobits_a;
alac->outputsamples_buffer_b[i] = audiobits_b;
}
}
else
{
int i;
for (i = 0; i < outputsamples; i++)
{
int32_t audiobits_a, audiobits_b;
audiobits_a = readbits(alac, 16);
audiobits_a = audiobits_a << (alac->setinfo_sample_size - 16);
audiobits_a |= readbits(alac, alac->setinfo_sample_size - 16);
audiobits_a = SignExtend24(audiobits_a);
audiobits_b = readbits(alac, 16);
audiobits_b = audiobits_b << (alac->setinfo_sample_size - 16);
audiobits_b |= readbits(alac, alac->setinfo_sample_size - 16);
audiobits_b = SignExtend24(audiobits_b);
alac->outputsamples_buffer_a[i] = audiobits_a;
alac->outputsamples_buffer_b[i] = audiobits_b;
}
}
uncompressed_bytes = 0; // always 0 for uncompressed
interlacing_shift = 0;
interlacing_leftweight = 0;
}
switch(alac->setinfo_sample_size)
{
case 16:
{
deinterlace_16(alac->outputsamples_buffer_a,
alac->outputsamples_buffer_b,
(int16_t*)outbuffer,
alac->numchannels,
outputsamples,
interlacing_shift,
interlacing_leftweight);
break;
}
case 24:
{
deinterlace_24(alac->outputsamples_buffer_a,
alac->outputsamples_buffer_b,
uncompressed_bytes,
alac->uncompressed_bytes_buffer_a,
alac->uncompressed_bytes_buffer_b,
(int16_t*)outbuffer,
alac->numchannels,
outputsamples,
interlacing_shift,
interlacing_leftweight);
break;
}
case 20:
case 32:
fprintf(stderr, "FIXME: unimplemented sample size %i\n", alac->setinfo_sample_size);
break;
default:
break;
}
break;
}
}
}
alac_file *create_alac(int samplesize, int numchannels)
{
alac_file *newfile = malloc(sizeof(alac_file));
newfile->samplesize = samplesize;
newfile->numchannels = numchannels;
newfile->bytespersample = (samplesize / 8) * numchannels;
return newfile;
}
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