/* * 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. * */ #if (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) static const int host_bigendian = 0; #else static const int host_bigendian = 1; #endif #include #include #include #include #include "alac.h" #define _fprintf fprintf #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); 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__) /* for some reason the unrolled version (below) is * actually faster than this. yay intel! */ static int count_leading_zeros(int input) { return __builtin_clz(input); } #elif (defined(_MSC_VER) || defined (__BORLANDC__)) && 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 #ifdef _MSC_VER #pragma message("using generic count leading zeroes. You may wish to write one for your CPU / compiler") #else #warning using generic count leading zeroes. You may wish to write one for your CPU / compiler #endif 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. static 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; } static 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++; } } } static 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; } } static 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; } void delete_alac(alac_file *alac) { free(alac->predicterror_buffer_a); free(alac->predicterror_buffer_b); free(alac->outputsamples_buffer_a); free(alac->outputsamples_buffer_b); free(alac->uncompressed_bytes_buffer_a); free(alac->uncompressed_bytes_buffer_b); free(alac); }