static pattern frame cache

internal/video/runner.go

@@ -35,6 +35,21 @@ func Run(ctx context.Context, inst *mxl.Instance, cfg Config) (runErr error) {
 		return err
 	}
 
+	var staticFrame []byte
+	if !pattern.dynamic {
+		frameSize := int(cfg.Width()*cfg.Height()) * 8 / 3
+		staticFrame = make([]byte, frameSize)
+
+		if err := gen.GenerateFrame(staticFrame, 0); err != nil {
+			return fmt.Errorf("generate static frame: %w", err)
+		}
+		if overlay != nil {
+			if err := overlay.ApplyV210(staticFrame); err != nil {
+				return fmt.Errorf("apply text overlay to static frame: %w", err)
+			}
+		}
+	}
+
 	flowJSON, err := json.Marshal(cfg.Definition)
 	if err != nil {
 		return fmt.Errorf("marshal video flow definition: %w", err)
@@ -70,13 +85,25 @@ func Run(ctx context.Context, inst *mxl.Instance, cfg Config) (runErr error) {
 		if err != nil {
 			return fmt.Errorf("open video grain %d: %w", idx, err)
 		}
-		if err := gen.GenerateFrame(grain.Payload, int(tick)); err != nil {
-			return cancelGrain(grain, fmt.Errorf("generate frame for grain %d: %w", idx, err))
-		}
-		if overlay != nil {
-			if err := overlay.ApplyV210(grain.Payload); err != nil {
-				return cancelGrain(grain, fmt.Errorf("apply text overlay to grain %d: %w", idx, err))
+		if staticFrame != nil {
+			if len(grain.Payload) != len(staticFrame) {
+				return cancelGrain(grain, fmt.Errorf(
+					"video grain payload size %d, expected %d",
+					len(grain.Payload),
+					len(staticFrame),
+				))
 			}
+			copy(grain.Payload, staticFrame)
+		} else {
+			if err := gen.GenerateFrame(grain.Payload, int(tick)); err != nil {
+				return cancelGrain(grain, fmt.Errorf("generate frame for grain %d: %w", idx, err))
+			}
+			if overlay != nil {
+				if err := overlay.ApplyV210(grain.Payload); err != nil {
+					return cancelGrain(grain, fmt.Errorf("apply text overlay to grain %d: %w", idx, err))
+				}
+			}
+			tick++
 		}
 		if err := grain.Commit(grain.TotalSlices, 0); err != nil {
 			return fmt.Errorf("commit video grain %d: %w", idx, err)
@@ -84,7 +111,6 @@ func Run(ctx context.Context, inst *mxl.Instance, cfg Config) (runErr error) {
 
 		grainsWritten++
 		idx++
-		tick++
 		if grainsWritten%100 == 0 {
 			log.Printf("video grains written=%d, next index=%d", grainsWritten, idx)
 		}