CPU patterns fallback

internal/video/runner.go

@@ -19,11 +19,11 @@ func Run(ctx context.Context, inst *mxl.Instance, cfg Config) (runErr error) {
 		return fmt.Errorf("unknown video pattern %q", cfg.Pattern)
 	}
 
-	// TODO: fall back to a CPU generator if GPU initialization fails.
-	gen, err := generator.NewWGPUGenerator(cfg.Width(), cfg.Height(), pattern.kernelSource)
+	gen, backend, err := newFrameGenerator(cfg, pattern)
 	if err != nil {
-		return fmt.Errorf("initialize wgpu video generator: %w", err)
+		return err
 	}
+	log.Printf("video generator backend: %s", backend)
 	defer func() {
 		if err := gen.Close(); err != nil {
 			runErr = errors.Join(runErr, fmt.Errorf("close video generator: %w", err))