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encoder complexity function update

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minjaesong
2025-09-08 23:58:25 +09:00
parent 79f8a25f41
commit b80d5b858a
1 changed files with 130 additions and 4 deletions
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134
video_encoder/encoder_tev.c
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@@ -216,6 +216,12 @@ typedef struct {
// Subtitle handling
subtitle_entry_t *subtitle_list;
subtitle_entry_t *current_subtitle;
// Complexity statistics collection
int stats_mode; // 0 = disabled, 1 = enabled
float *complexity_values; // Array to store all complexity values
int complexity_count; // Current count of complexity values
int complexity_capacity; // Capacity of complexity_values array
} tev_encoder_t;
// RGB to YCoCg-R transform (per YCoCg-R specification with truncated division)
@@ -461,11 +467,119 @@ static float calculate_block_complexity(const float *y_block) {
}
// Map complexity to rate control factor (pure per-block, no global factor)
// Data-driven approach: rate_control_factor multiplies reconstructed coefficients in decoder
// Higher factor = more detail preserved, lower factor = acceptable quality loss
static float complexity_to_rate_factor(float complexity) {
const float P = 10.f;
const float e = -0.5f;
float factor = P * powf(FCLAMP(complexity, 1.f, 16777216.f), e);
return FCLAMP(factor, 1.f / 2.f, 2.f); // the "auto quality" thing can be excessively permissive
// Handle zero/near-zero complexity (very common in sample data)
if (complexity <= 0.001f) {
return 0.7f; // Reduce detail for flat blocks (saves bits, minimal perceptual loss)
}
// Parameters derived from statistical analysis of 10 video samples:
// - Most content has median complexity around 500-3000
// - Heavy concentration at low complexity, wide spread at high complexity
const float median_complexity = 2400.0f; // Target for rate_factor = 1.0
const float high_complexity = 8500.0f; // ~91st percentile threshold
// Logarithmic preprocessing to handle wide dynamic range (0 to 17000+)
float log_complexity = logf(complexity + 1.0f);
float log_median = logf(median_complexity + 1.0f);
float log_high = logf(high_complexity + 1.0f);
// Normalize: 0 = median complexity, 1 = high complexity threshold
float normalized = (log_complexity - log_median) / (log_high - log_median);
// Sigmoid centered at median: f(0) ≈ 1.0, f(1) ≈ 1.6, f(-∞) ≈ 0.7
float sigmoid = 1.0f / (1.0f + expf(-4.0f * normalized));
float rate_factor = 0.7f + 0.9f * sigmoid; // Range: 0.7 to 1.6
// Clamp to prevent extreme coefficient amplification/reduction
return FCLAMP(rate_factor, 0.6f, 1.8f);
}
// Add complexity value to statistics collection
static void add_complexity_value(tev_encoder_t *enc, float complexity) {
if (!enc->stats_mode) return;
// Initialize array if needed
if (!enc->complexity_values) {
enc->complexity_capacity = 10000; // Initial capacity
enc->complexity_values = malloc(enc->complexity_capacity * sizeof(float));
if (!enc->complexity_values) {
fprintf(stderr, "Warning: Failed to allocate complexity statistics array\n");
enc->stats_mode = 0;
return;
}
enc->complexity_count = 0;
}
// Resize array if needed
if (enc->complexity_count >= enc->complexity_capacity) {
enc->complexity_capacity *= 2;
float *new_array = realloc(enc->complexity_values, enc->complexity_capacity * sizeof(float));
if (!new_array) {
fprintf(stderr, "Warning: Failed to resize complexity statistics array\n");
return;
}
enc->complexity_values = new_array;
}
enc->complexity_values[enc->complexity_count++] = complexity;
}
// Comparison function for qsort
static int compare_float(const void *a, const void *b) {
float fa = *(const float*)a;
float fb = *(const float*)b;
if (fa < fb) return -1;
if (fa > fb) return 1;
return 0;
}
// Calculate seven-number summary statistics
static void calculate_complexity_stats(tev_encoder_t *enc) {
if (!enc->stats_mode || enc->complexity_count == 0) return;
printf("\n=== BLOCK COMPLEXITY STATISTICS ===\n");
printf("Analyzed %d blocks during encoding\n\n", enc->complexity_count);
// Sort the values to calculate percentiles
float *sorted_values = malloc(enc->complexity_count * sizeof(float));
if (!sorted_values) {
fprintf(stderr, "Failed to allocate memory for statistics calculation\n");
return;
}
memcpy(sorted_values, enc->complexity_values, enc->complexity_count * sizeof(float));
qsort(sorted_values, enc->complexity_count, sizeof(float), compare_float);
// Calculate seven-number summary percentiles: 2.15%, 8.87%, 25%, 50%, 75%, 91.13%, 97.85%
float p2_15 = sorted_values[(int)(0.0215 * (enc->complexity_count - 1))];
float p8_87 = sorted_values[(int)(0.0887 * (enc->complexity_count - 1))];
float p25 = sorted_values[(int)(0.25 * (enc->complexity_count - 1))];
float p50 = sorted_values[(int)(0.50 * (enc->complexity_count - 1))];
float p75 = sorted_values[(int)(0.75 * (enc->complexity_count - 1))];
float p91_13 = sorted_values[(int)(0.9113 * (enc->complexity_count - 1))];
float p97_85 = sorted_values[(int)(0.9785 * (enc->complexity_count - 1))];
// Print human-readable format
printf("Seven-Number Summary:\n");
printf(" 2.15%% percentile: %.6f\n", p2_15);
printf(" 8.87%% percentile: %.6f\n", p8_87);
printf(" 25.0%% percentile: %.6f\n", p25);
printf(" 50.0%% percentile: %.6f\n", p50);
printf(" 75.0%% percentile: %.6f\n", p75);
printf(" 91.13%% percentile: %.6f\n", p91_13);
printf(" 97.85%% percentile: %.6f\n", p97_85);
// Print CSV format for copy-pasting
printf("CSV Format (copy-pastable):\n");
printf("2.15%%,8.87%%,25.0%%,50.0%%,75.0%%,91.13%%,97.85%%\n");
printf("%.6f,%.6f,%.6f,%.6f,%.6f,%.6f,%.6f\n", p2_15, p8_87, p25, p50, p75, p91_13, p97_85);
free(sorted_values);
printf("=====================================\n");
}
// Simple motion estimation (full search) for 16x16 blocks
@@ -749,6 +863,7 @@ static void encode_block(tev_encoder_t *enc, int block_x, int block_y, int is_ke
block->mv_y = 0;
// Even skip blocks benefit from complexity analysis for consistency
float block_complexity = calculate_block_complexity(enc->y_workspace);
add_complexity_value(enc, block_complexity);
block->rate_control_factor = complexity_to_rate_factor(block_complexity);
block->cbp = 0x00; // No coefficients present
// Zero out DCT coefficients for consistent format
@@ -763,6 +878,7 @@ static void encode_block(tev_encoder_t *enc, int block_x, int block_y, int is_ke
block->mode = TEV_MODE_MOTION;
// Analyze complexity for motion blocks too
float block_complexity = calculate_block_complexity(enc->y_workspace);
add_complexity_value(enc, block_complexity);
block->rate_control_factor = complexity_to_rate_factor(block_complexity);
block->cbp = 0x00; // No coefficients present
// Zero out DCT coefficients for consistent format
@@ -807,6 +923,7 @@ static void encode_block(tev_encoder_t *enc, int block_x, int block_y, int is_ke
// Calculate block complexity BEFORE DCT transform for adaptive rate control
float block_complexity = calculate_block_complexity(enc->y_workspace);
add_complexity_value(enc, block_complexity);
block->rate_control_factor = complexity_to_rate_factor(block_complexity);
// Apply fast DCT transform
@@ -1513,6 +1630,7 @@ static void free_encoder(tev_encoder_t *enc) {
if (enc->block_data) { free(enc->block_data); enc->block_data = NULL; }
if (enc->compressed_buffer) { free(enc->compressed_buffer); enc->compressed_buffer = NULL; }
if (enc->mp2_buffer) { free(enc->mp2_buffer); enc->mp2_buffer = NULL; }
if (enc->complexity_values) { free(enc->complexity_values); enc->complexity_values = NULL; }
free(enc);
}
@@ -2045,6 +2163,7 @@ static void show_usage(const char *program_name) {
printf(" -S, --subtitles FILE SubRip (.srt) or SAMI (.smi) subtitle file\n");
printf(" -v, --verbose Verbose output\n");
printf(" -t, --test Test mode: generate solid colour frames\n");
printf(" --enable-encode-stats Collect and report block complexity statistics\n");
printf(" --help Show this help\n\n");
// printf("Rate Control Modes:\n");
// printf(" Quality mode (default): Fixed quantisation based on -q parameter\n");
@@ -2132,6 +2251,7 @@ int main(int argc, char *argv[]) {
{"progressive", no_argument, 0, 'p'},
{"verbose", no_argument, 0, 'v'},
{"test", no_argument, 0, 't'},
{"enable-encode-stats", no_argument, 0, 1000},
{"help", no_argument, 0, '?'},
{0, 0, 0, 0}
};
@@ -2200,6 +2320,9 @@ int main(int argc, char *argv[]) {
case 't':
test_mode = 1;
break;
case 1000: // --enable-encode-stats
enc->stats_mode = 1;
break;
case 0:
if (strcmp(long_options[option_index].name, "help") == 0) {
show_usage(argv[0]);
@@ -2482,6 +2605,9 @@ int main(int argc, char *argv[]) {
printf(" Per-block complexity-based rate control: enabled\n");
}
// Print complexity statistics if enabled
calculate_complexity_stats(enc);
cleanup_encoder(enc);
return 0;
}