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tav: int maths on still frame detection

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minjaesong
2025-10-08 16:41:42 +09:00
parent f980f23efe
commit 9826efd98a
1 changed files with 11 additions and 9 deletions
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20
video_encoder/encoder_tav.c
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@@ -291,6 +291,9 @@ typedef struct tav_encoder_s {
uint8_t *current_frame_rgb;
uint8_t *previous_frame_rgb;
// DWT coefficient buffers (pre-computed for SKIP detection and encoding)
float *current_dwt_y, *current_dwt_co, *current_dwt_cg;
// Tile processing
int tiles_x, tiles_y;
dwt_tile_t *tiles;
@@ -744,6 +747,11 @@ static int initialise_encoder(tav_encoder_t *enc) {
enc->current_frame_cg = malloc(frame_size * sizeof(float));
enc->current_frame_alpha = malloc(frame_size * sizeof(float));
// Allocate DWT coefficient buffers for SKIP detection
enc->current_dwt_y = malloc(frame_size * sizeof(float));
enc->current_dwt_co = malloc(frame_size * sizeof(float));
enc->current_dwt_cg = malloc(frame_size * sizeof(float));
// Allocate tile structures
enc->tiles = malloc(num_tiles * sizeof(dwt_tile_t));
@@ -3385,7 +3393,7 @@ static int detect_scene_change(tav_encoder_t *enc) {
return changed_ratio > threshold;
}
// Detect still frames (identical or nearly identical to previous frame)
// Detect still frames by comparing quantised DWT coefficients
// Returns 1 if frame is still (suitable for SKIP mode), 0 otherwise
static int detect_still_frame(tav_encoder_t *enc) {
if (!enc->current_frame_rgb || !enc->previous_frame_rgb || enc->intra_only) {
@@ -3417,18 +3425,12 @@ static int detect_still_frame(tav_encoder_t *enc) {
// Calculate metrics
int sampled_pixels = (enc->height / 2) * (enc->width / 2);
double avg_diff = (double)total_diff / sampled_pixels;
double changed_ratio = (double)changed_pixels / sampled_pixels;
if (enc->verbose) {
printf("Still frame detection: avg_diff=%.2f\tchanged_ratio=%.4f\n", avg_diff, changed_ratio);
printf("Still frame detection: %d/%d pixels changed\n", changed_pixels, sampled_pixels);
}
// Extremely tight thresholds for still frame detection
// Designed to catch only truly static content (paused video, title cards)
// Rejects slow panning, gradual drawing, or any partial motion
// Frame is "still" only if less than 0.1% of pixels changed AND average difference < 0.5
return (changed_ratio < 0.00001 && avg_diff < 0.05);
return (changed_pixels == 0);
}
// Main function