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optimising and rotating DCT blocks

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This commit is contained in:
minjaesong
2025-08-22 00:46:19 +09:00
parent 270864ef0f
commit b720e786a9
2 changed files with 123 additions and 41 deletions
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87
video_encoder/encoder_tev.c
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@@ -367,7 +367,43 @@ static void init_dct_tables(void) {
tables_initialized = 1;
}
// Optimized 16x16 2D DCT
// 16x16 2D DCT
// Fast separable 16x16 DCT - 8x performance improvement
static float temp_dct_16[256]; // Reusable temporary buffer
static void dct_16x16_fast(float *input, float *output) {
init_dct_tables(); // Ensure tables are initialized
// First pass: Process rows (16 1D DCTs)
for (int row = 0; row < 16; row++) {
for (int u = 0; u < 16; u++) {
float sum = 0.0f;
float cu = (u == 0) ? 1.0f / sqrtf(2.0f) : 1.0f;
for (int x = 0; x < 16; x++) {
sum += input[row * 16 + x] * dct_table_16[u][x];
}
temp_dct_16[row * 16 + u] = 0.5f * cu * sum;
}
}
// Second pass: Process columns (16 1D DCTs)
for (int col = 0; col < 16; col++) {
for (int v = 0; v < 16; v++) {
float sum = 0.0f;
float cv = (v == 0) ? 1.0f / sqrtf(2.0f) : 1.0f;
for (int y = 0; y < 16; y++) {
sum += temp_dct_16[y * 16 + col] * dct_table_16[v][y];
}
output[v * 16 + col] = 0.5f * cv * sum;
}
}
}
// Legacy O(n^4) version for reference/fallback
static void dct_16x16(float *input, float *output) {
init_dct_tables(); // Ensure tables are initialized
@@ -390,7 +426,42 @@ static void dct_16x16(float *input, float *output) {
}
}
// Optimized 8x8 2D DCT (for chroma)
// Fast separable 8x8 DCT - 4x performance improvement
static float temp_dct_8[64]; // Reusable temporary buffer
static void dct_8x8_fast(float *input, float *output) {
init_dct_tables(); // Ensure tables are initialized
// First pass: Process rows (8 1D DCTs)
for (int row = 0; row < 8; row++) {
for (int u = 0; u < 8; u++) {
float sum = 0.0f;
float cu = (u == 0) ? 1.0f / sqrtf(2.0f) : 1.0f;
for (int x = 0; x < 8; x++) {
sum += input[row * 8 + x] * dct_table_8[u][x];
}
temp_dct_8[row * 8 + u] = 0.5f * cu * sum;
}
}
// Second pass: Process columns (8 1D DCTs)
for (int col = 0; col < 8; col++) {
for (int v = 0; v < 8; v++) {
float sum = 0.0f;
float cv = (v == 0) ? 1.0f / sqrtf(2.0f) : 1.0f;
for (int y = 0; y < 8; y++) {
sum += temp_dct_8[y * 8 + col] * dct_table_8[v][y];
}
output[v * 8 + col] = 0.5f * cv * sum;
}
}
}
// Legacy 8x8 2D DCT (for chroma) - O(n^4) version
static void dct_8x8(float *input, float *output) {
init_dct_tables(); // Ensure tables are initialized
@@ -807,8 +878,8 @@ static void encode_block(tev_encoder_t *enc, int block_x, int block_y, int is_ke
}
}
// Apply DCT transform
dct_16x16(enc->y_workspace, enc->dct_workspace);
// Apply fast DCT transform - 8x performance improvement
dct_16x16_fast(enc->y_workspace, enc->dct_workspace);
// Quantize Y coefficients (luma)
const uint8_t *y_quant = QUANT_TABLES_Y[enc->quality];
@@ -816,8 +887,8 @@ static void encode_block(tev_encoder_t *enc, int block_x, int block_y, int is_ke
block->y_coeffs[i] = quantize_coeff(enc->dct_workspace[i], y_quant[i], i == 0, 0);
}
// Apply DCT transform to chroma
dct_8x8(enc->co_workspace, enc->dct_workspace);
// Apply fast DCT transform to chroma - 4x performance improvement
dct_8x8_fast(enc->co_workspace, enc->dct_workspace);
// Quantize Co coefficients (chroma)
const uint8_t *c_quant = QUANT_TABLES_C[enc->quality];
@@ -825,8 +896,8 @@ static void encode_block(tev_encoder_t *enc, int block_x, int block_y, int is_ke
block->co_coeffs[i] = quantize_coeff(enc->dct_workspace[i], c_quant[i], i == 0, 1);
}
// Apply DCT transform to Cg
dct_8x8(enc->cg_workspace, enc->dct_workspace);
// Apply fast DCT transform to Cg - 4x performance improvement
dct_8x8_fast(enc->cg_workspace, enc->dct_workspace);
// Quantize Cg coefficients (chroma)
for (int i = 0; i < 64; i++) {