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TAD: arbitrary steps with bitplanes

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minjaesong
2025-10-27 09:14:52 +09:00
parent 9c27d114fc
commit 1d0f369827
5 changed files with 226 additions and 53 deletions
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32
video_encoder/decoder_tad.c
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@@ -337,7 +337,7 @@ static void pcm32f_to_pcm8(const float *fleft, const float *fright, uint8_t *lef
// Lambda-based decompanding decoder (inverse of Laplacian CDF-based encoder)
// Converts quantized index back to normalized float in [-1, 1]
static float lambda_decompanding(int16_t quant_val, int quant_bits) {
static float lambda_decompanding(int16_t quant_val, int max_index) {
// Handle zero
if (quant_val == 0) {
return 0.0f;
@@ -346,9 +346,6 @@ static float lambda_decompanding(int16_t quant_val, int quant_bits) {
int sign = (quant_val < 0) ? -1 : 1;
int abs_index = abs(quant_val);
// Maximum index for the given quant_bits
int max_index = (1 << (quant_bits - 1)) - 1;
// Clamp to valid range
if (abs_index > max_index) abs_index = max_index;
@@ -369,7 +366,7 @@ static float lambda_decompanding(int16_t quant_val, int quant_bits) {
return sign * abs_val;
}
static void dequantize_dwt_coefficients(const int16_t *quantized, float *coeffs, size_t count, int chunk_size, int dwt_levels, int quant_bits) {
static void dequantize_dwt_coefficients(const int16_t *quantized, float *coeffs, size_t count, int chunk_size, int dwt_levels, int max_index) {
// Calculate sideband boundaries dynamically
int first_band_size = chunk_size >> dwt_levels;
@@ -391,7 +388,7 @@ static void dequantize_dwt_coefficients(const int16_t *quantized, float *coeffs,
}
// Decode using lambda companding
float normalized_val = lambda_decompanding(quantized[i], quant_bits);
float normalized_val = lambda_decompanding(quantized[i], max_index);
// Denormalize using the subband scalar
coeffs[i] = normalized_val * TAD32_COEFF_SCALARS[sideband];
@@ -409,8 +406,8 @@ static void dequantize_dwt_coefficients(const int16_t *quantized, float *coeffs,
// Sign bit: 0 = positive/zero, 1 = negative
// Magnitude: unsigned value [0, 2^quant_bits - 1]
// Delta prediction: plane[i] ^= plane[i-1] (reversed by same operation)
static size_t decode_bitplanes(const uint8_t *input, int16_t *values, size_t count, int quant_bits) {
int bits_per_coeff = quant_bits + 1; // 1 sign bit + quant_bits magnitude bits
static size_t decode_bitplanes(const uint8_t *input, int16_t *values, size_t count, int max_index) {
int bits_per_coeff = ((int)ceilf(log2f(max_index))) + 1; // 1 sign bit + quant_bits magnitude bits
size_t plane_bytes = (count + 7) / 8; // Bytes needed for one bitplane
size_t input_bytes = plane_bytes * bits_per_coeff;
@@ -421,13 +418,6 @@ static size_t decode_bitplanes(const uint8_t *input, int16_t *values, size_t cou
memcpy(bitplanes[plane], input + (plane * plane_bytes), plane_bytes);
}
// Reverse delta prediction: plane[i] ^= plane[i-1]
for (int plane = 0; plane < bits_per_coeff; plane++) {
for (size_t byte = 1; byte < plane_bytes; byte++) {
bitplanes[plane][byte] ^= bitplanes[plane][byte - 1];
}
}
// Reconstruct coefficients from bitplanes
for (size_t i = 0; i < count; i++) {
size_t byte_idx = i / 8;
@@ -438,7 +428,7 @@ static size_t decode_bitplanes(const uint8_t *input, int16_t *values, size_t cou
// Read magnitude bits (planes 1 to quant_bits)
uint16_t magnitude = 0;
for (int b = 0; b < quant_bits; b++) {
for (int b = 0; b < bits_per_coeff - 1; b++) {
if (bitplanes[b + 1][byte_idx] & (1 << bit_offset)) {
magnitude |= (1 << b);
}
@@ -469,7 +459,7 @@ static int decode_chunk(const uint8_t *input, size_t input_size, uint8_t *pcmu8_
uint16_t sample_count = *((const uint16_t*)read_ptr);
read_ptr += sizeof(uint16_t);
uint8_t quant_bits = *read_ptr;
uint8_t max_index = *read_ptr;
read_ptr += sizeof(uint8_t);
uint32_t payload_size = *((const uint32_t*)read_ptr);
@@ -518,12 +508,12 @@ static int decode_chunk(const uint8_t *input, size_t input_size, uint8_t *pcmu8_
const uint8_t *payload_ptr = payload;
size_t mid_bytes, side_bytes;
mid_bytes = decode_bitplanes(payload_ptr, quant_mid, sample_count, quant_bits);
side_bytes = decode_bitplanes(payload_ptr + mid_bytes, quant_side, sample_count, quant_bits);
mid_bytes = decode_bitplanes(payload_ptr, quant_mid, sample_count, max_index);
side_bytes = decode_bitplanes(payload_ptr + mid_bytes, quant_side, sample_count, max_index);
// Dequantize
dequantize_dwt_coefficients(quant_mid, dwt_mid, sample_count, sample_count, dwt_levels, quant_bits);
dequantize_dwt_coefficients(quant_side, dwt_side, sample_count, sample_count, dwt_levels, quant_bits);
dequantize_dwt_coefficients(quant_mid, dwt_mid, sample_count, sample_count, dwt_levels, max_index);
dequantize_dwt_coefficients(quant_side, dwt_side, sample_count, sample_count, dwt_levels, max_index);
// Inverse DWT
dwt_haar_inverse_multilevel(dwt_mid, sample_count, dwt_levels);