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@ -366,22 +366,7 @@ unsigned int qoa_encode_frame(const short *sample_data, qoa_desc *qoa, unsigned |
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), bytes, &p); |
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for (int c = 0; c < channels; c++) { |
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/* If the weights have grown too large, reset them to 0. This may happen |
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with certain high-frequency sounds. This is a last resort and will |
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introduce quite a bit of noise, but should at least prevent pops/clicks */ |
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int weights_sum = |
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qoa->lms[c].weights[0] * qoa->lms[c].weights[0] + |
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qoa->lms[c].weights[1] * qoa->lms[c].weights[1] + |
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qoa->lms[c].weights[2] * qoa->lms[c].weights[2] + |
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qoa->lms[c].weights[3] * qoa->lms[c].weights[3]; |
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if (weights_sum > 0x2fffffff) { |
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qoa->lms[c].weights[0] = 0; |
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qoa->lms[c].weights[1] = 0; |
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qoa->lms[c].weights[2] = 0; |
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qoa->lms[c].weights[3] = 0; |
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} |
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for (unsigned int c = 0; c < channels; c++) { |
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/* Write the current LMS state */ |
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qoa_uint64_t weights = 0; |
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qoa_uint64_t history = 0; |
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@ -395,9 +380,9 @@ unsigned int qoa_encode_frame(const short *sample_data, qoa_desc *qoa, unsigned |
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/* We encode all samples with the channels interleaved on a slice level. |
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E.g. for stereo: (ch-0, slice 0), (ch 1, slice 0), (ch 0, slice 1), ...*/ |
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for (int sample_index = 0; sample_index < frame_len; sample_index += QOA_SLICE_LEN) { |
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for (unsigned int sample_index = 0; sample_index < frame_len; sample_index += QOA_SLICE_LEN) { |
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for (int c = 0; c < channels; c++) { |
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for (unsigned int c = 0; c < channels; c++) { |
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int slice_len = qoa_clamp(QOA_SLICE_LEN, 0, frame_len - sample_index); |
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int slice_start = sample_index * channels + c; |
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int slice_end = (sample_index + slice_len) * channels + c; |
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@ -405,10 +390,13 @@ unsigned int qoa_encode_frame(const short *sample_data, qoa_desc *qoa, unsigned |
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/* Brute for search for the best scalefactor. Just go through all |
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16 scalefactors, encode all samples for the current slice and |
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meassure the total squared error. */ |
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qoa_uint64_t best_error = -1; |
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qoa_uint64_t best_slice; |
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qoa_uint64_t best_rank = -1; |
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#ifdef QOA_RECORD_TOTAL_ERROR |
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qoa_uint64_t best_error = -1; |
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#endif |
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qoa_uint64_t best_slice = 0; |
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qoa_lms_t best_lms; |
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int best_scalefactor; |
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int best_scalefactor = 0; |
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for (int sfi = 0; sfi < 16; sfi++) { |
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/* There is a strong correlation between the scalefactors of |
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@ -421,7 +409,10 @@ unsigned int qoa_encode_frame(const short *sample_data, qoa_desc *qoa, unsigned |
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state when encoding. */ |
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qoa_lms_t lms = qoa->lms[c]; |
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qoa_uint64_t slice = scalefactor; |
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qoa_uint64_t current_error = 0; |
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qoa_uint64_t current_rank = 0; |
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#ifdef QOA_RECORD_TOTAL_ERROR |
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qoa_uint64_t current_error = 0; |
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#endif |
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for (int si = slice_start; si < slice_end; si += channels) { |
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int sample = sample_data[si]; |
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@ -434,9 +425,27 @@ unsigned int qoa_encode_frame(const short *sample_data, qoa_desc *qoa, unsigned |
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int dequantized = qoa_dequant_tab[scalefactor][quantized]; |
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int reconstructed = qoa_clamp_s16(predicted + dequantized); |
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/* If the weights have grown too large, we introduce a penalty |
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here. This prevents pops/clicks in certain problem cases */ |
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int weights_penalty = (( |
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lms.weights[0] * lms.weights[0] + |
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lms.weights[1] * lms.weights[1] + |
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lms.weights[2] * lms.weights[2] + |
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lms.weights[3] * lms.weights[3] |
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) >> 18) - 0x8ff; |
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if (weights_penalty < 0) { |
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weights_penalty = 0; |
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} |
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long long error = (sample - reconstructed); |
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current_error += error * error; |
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if (current_error > best_error) { |
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qoa_uint64_t error_sq = error * error; |
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current_rank += error_sq + weights_penalty * weights_penalty; |
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#ifdef QOA_RECORD_TOTAL_ERROR |
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current_error += error_sq; |
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#endif |
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if (current_rank > best_rank) { |
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break; |
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} |
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@ -444,8 +453,11 @@ unsigned int qoa_encode_frame(const short *sample_data, qoa_desc *qoa, unsigned |
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slice = (slice << 3) | quantized; |
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} |
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if (current_error < best_error) { |
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best_error = current_error; |
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if (current_rank < best_rank) { |
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best_rank = current_rank; |
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#ifdef QOA_RECORD_TOTAL_ERROR |
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best_error = current_error; |
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#endif |
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best_slice = slice; |
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best_lms = lms; |
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best_scalefactor = scalefactor; |
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@ -490,7 +502,7 @@ void *qoa_encode(const short *sample_data, qoa_desc *qoa, unsigned int *out_len) |
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unsigned char *bytes = QOA_MALLOC(encoded_size); |
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for (int c = 0; c < qoa->channels; c++) { |
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for (unsigned int c = 0; c < qoa->channels; c++) { |
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/* Set the initial LMS weights to {0, 0, -1, 2}. This helps with the |
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prediction of the first few ms of a file. */ |
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qoa->lms[c].weights[0] = 0; |
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@ -513,7 +525,7 @@ void *qoa_encode(const short *sample_data, qoa_desc *qoa, unsigned int *out_len) |
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#endif |
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int frame_len = QOA_FRAME_LEN; |
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for (int sample_index = 0; sample_index < qoa->samples; sample_index += frame_len) { |
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for (unsigned int sample_index = 0; sample_index < qoa->samples; sample_index += frame_len) { |
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frame_len = qoa_clamp(QOA_FRAME_LEN, 0, qoa->samples - sample_index); |
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const short *frame_samples = sample_data + sample_index * qoa->channels; |
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unsigned int frame_size = qoa_encode_frame(frame_samples, qoa, frame_len, bytes + p); |
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@ -576,14 +588,14 @@ unsigned int qoa_decode_frame(const unsigned char *bytes, unsigned int size, qoa |
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/* Read and verify the frame header */ |
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qoa_uint64_t frame_header = qoa_read_u64(bytes, &p); |
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int channels = (frame_header >> 56) & 0x0000ff; |
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int samplerate = (frame_header >> 32) & 0xffffff; |
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int samples = (frame_header >> 16) & 0x00ffff; |
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int frame_size = (frame_header ) & 0x00ffff; |
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unsigned int channels = (frame_header >> 56) & 0x0000ff; |
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unsigned int samplerate = (frame_header >> 32) & 0xffffff; |
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unsigned int samples = (frame_header >> 16) & 0x00ffff; |
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unsigned int frame_size = (frame_header ) & 0x00ffff; |
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int data_size = frame_size - 8 - QOA_LMS_LEN * 4 * channels; |
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int num_slices = data_size / 8; |
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int max_total_samples = num_slices * QOA_SLICE_LEN; |
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unsigned int data_size = frame_size - 8 - QOA_LMS_LEN * 4 * channels; |
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unsigned int num_slices = data_size / 8; |
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unsigned int max_total_samples = num_slices * QOA_SLICE_LEN; |
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if ( |
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channels != qoa->channels || |
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@ -596,7 +608,7 @@ unsigned int qoa_decode_frame(const unsigned char *bytes, unsigned int size, qoa |
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/* Read the LMS state: 4 x 2 bytes history, 4 x 2 bytes weights per channel */ |
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for (int c = 0; c < channels; c++) { |
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for (unsigned int c = 0; c < channels; c++) { |
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qoa_uint64_t history = qoa_read_u64(bytes, &p); |
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qoa_uint64_t weights = qoa_read_u64(bytes, &p); |
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for (int i = 0; i < QOA_LMS_LEN; i++) { |
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@ -609,17 +621,19 @@ unsigned int qoa_decode_frame(const unsigned char *bytes, unsigned int size, qoa |
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/* Decode all slices for all channels in this frame */ |
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for (int sample_index = 0; sample_index < samples; sample_index += QOA_SLICE_LEN) { |
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for (int c = 0; c < channels; c++) { |
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for (unsigned int sample_index = 0; sample_index < samples; sample_index += QOA_SLICE_LEN) { |
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for (unsigned int c = 0; c < channels; c++) { |
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qoa_uint64_t slice = qoa_read_u64(bytes, &p); |
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int scalefactor = (slice >> 60) & 0xf; |
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slice <<= 4; |
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int slice_start = sample_index * channels + c; |
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int slice_end = qoa_clamp(sample_index + QOA_SLICE_LEN, 0, samples) * channels + c; |
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for (int si = slice_start; si < slice_end; si += channels) { |
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int predicted = qoa_lms_predict(&qoa->lms[c]); |
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int quantized = (slice >> 57) & 0x7; |
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int quantized = (slice >> 61) & 0x7; |
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int dequantized = qoa_dequant_tab[scalefactor][quantized]; |
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int reconstructed = qoa_clamp_s16(predicted + dequantized); |
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