✨ feat: color frames, derive grayscale frames at render time

.env.example

@@ -26,6 +26,8 @@ CHARSET=blocks
 BRIGHTNESS_THRESHOLD=40
 # Invert the brightness ramp (for light terminal backgrounds).
 INVERT=false
+# Always render grayscale, even for clients that support color.
+FORCE_GRAYSCALE=false
 
 # Max rendered width/height in characters.
 MAX_DIMENSION=1080
@@ -39,7 +41,7 @@ MAX_TOTAL_CONNECTIONS=1000
 # (Empty password counts as an attempt.)
 MAX_AUTH_ATTEMPTS=3
 # SSH handshake deadline in ms (0 to disable).
-HANDSHAKE_TIMEOUT=10000
+HANDSHAKE_TIMEOUT=30000
 
 # Log attempted usernames/passwords.
 LOG_CREDENTIALS=true

src/app_test.go

@@ -12,7 +12,7 @@ func TestTSFRoundTrip(t *testing.T) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "f.tsf")
 	original := &FramesContainer{
-		Frames: [][]byte{{0, 1, 255}, {10, 20, 30}},
+		ColorFrames: [][]byte{{100, 101, 102}, {110, 120, 130}},
 		FPS:         29.97,
 	}
 	if err := writeTSF(path, original); err != nil {
@@ -25,14 +25,14 @@ func TestTSFRoundTrip(t *testing.T) {
 	if fc.FPS != 29.97 {
 		t.Errorf("fps = %v", fc.FPS)
 	}
-	if len(fc.Frames) != 2 {
-		t.Fatalf("frames = %d", len(fc.Frames))
+	if len(fc.ColorFrames) != 2 {
+		t.Fatalf("frames = %d color", len(fc.ColorFrames))
 	}
-	if string(fc.Frames[0]) != string([]byte{0, 1, 255}) {
-		t.Errorf("frame0 = %v", fc.Frames[0])
+	if string(fc.ColorFrames[0]) != string([]byte{100, 101, 102}) {
+		t.Errorf("color frame0 = %v", fc.ColorFrames[0])
 	}
-	if string(fc.Frames[1]) != string([]byte{10, 20, 30}) {
-		t.Errorf("frame1 = %v", fc.Frames[1])
+	if string(fc.ColorFrames[1]) != string([]byte{110, 120, 130}) {
+		t.Errorf("color frame1 = %v", fc.ColorFrames[1])
 	}
 }
 
@@ -52,13 +52,13 @@ func TestTSFInvalid(t *testing.T) {
 	}
 
 	// Valid container but fps <= 0.
-	writeTSF(path, &FramesContainer{Frames: [][]byte{{1}}, FPS: 0})
+	writeTSF(path, &FramesContainer{ColorFrames: [][]byte{{1}}, FPS: 0})
 	if _, err := loadTSF(path); err == nil {
 		t.Error("expected error for fps<=0")
 	}
 
 	// Truncated payload.
-	writeTSF(path, &FramesContainer{Frames: [][]byte{{1, 2, 3, 4}}, FPS: 30})
+	writeTSF(path, &FramesContainer{ColorFrames: [][]byte{{1, 2, 3, 4}}, FPS: 30})
 	raw, _ := os.ReadFile(path)
 	os.WriteFile(path, raw[:len(raw)-2], 0o644)
 	if _, err := loadTSF(path); err == nil {
@@ -215,4 +215,38 @@ func TestParseDimsPtyReq(t *testing.T) {
 	if !ok || cols != 100 || rows != 40 {
 		t.Errorf("parseDims = %d,%d,%v", cols, rows, ok)
 	}
+
+	term, ok := parsePtyTerm(payload)
+	if !ok || term != "xterm" {
+		t.Errorf("parsePtyTerm = %q,%v", term, ok)
+	}
+}
+
+func TestDetectColorTier(t *testing.T) {
+	cases := map[string]colorTier{
+		"":                colorTierNone,
+		"dumb":            colorTierNone,
+		"vt100":           colorTierNone,
+		"linux":           colorTierNone,
+		"xterm":           colorTierTrueColor,
+		"xterm-256color":  colorTier256,
+		"screen-256color": colorTier256,
+		"tmux-256color":   colorTier256,
+		"xterm-direct":    colorTierTrueColor,
+		"xterm-kitty":     colorTierTrueColor,
+	}
+	for term, want := range cases {
+		if got := detectColorTier(term); got != want {
+			t.Errorf("detectColorTier(%q) = %d, want %d", term, got, want)
+		}
+	}
+}
+
+func TestQuantize256(t *testing.T) {
+	if got := quantize256(0, 0, 0); got != 16 {
+		t.Errorf("black = %d, want 16", got)
+	}
+	if got := quantize256(255, 255, 255); got != 231 {
+		t.Errorf("white = %d, want 231", got)
+	}
 }

src/config.go

@@ -32,6 +32,7 @@ type Config struct {
 	BrightnessThreshold int
 	Charset             string
 	Invert              bool
+	ForceGrayscale      bool
 	LogCredentials      bool
 }
 
@@ -129,6 +130,7 @@ func loadConfig() Config {
 		BrightnessThreshold: envInt("BRIGHTNESS_THRESHOLD", 40, 0, 100),
 		Charset:             envString("CHARSET", "detailed"),
 		Invert:              envBool("INVERT", false),
+		ForceGrayscale:      envBool("FORCE_GRAYSCALE", false),
 		LogCredentials:      envBool("LOG_CREDENTIALS", false),
 	}
 }

src/frameformat.go

@@ -9,7 +9,7 @@ import (
 )
 
 // .tsf container, little-endian: "TSFR" | version uint16 | fps float64 |
-// count uint32 | count × (length uint32, JPEG bytes).
+// count uint32 | count × (colorLen uint32, color JPEG).
 const (
 	tsfMagic   = "TSFR"
 	tsfVersion = 1
@@ -29,13 +29,13 @@ func writeTSF(output string, data *FramesContainer) error {
 	var hdr [14]byte
 	binary.LittleEndian.PutUint16(hdr[0:], tsfVersion)
 	binary.LittleEndian.PutUint64(hdr[2:], math.Float64bits(data.FPS))
-	binary.LittleEndian.PutUint32(hdr[10:], uint32(len(data.Frames)))
+	binary.LittleEndian.PutUint32(hdr[10:], uint32(len(data.ColorFrames)))
 	if _, err := w.Write(hdr[:]); err != nil {
 		return err
 	}
 
 	var lenBuf [4]byte
-	for _, frame := range data.Frames {
+	for _, frame := range data.ColorFrames {
 		binary.LittleEndian.PutUint32(lenBuf[:], uint32(len(frame)))
 		if _, err := w.Write(lenBuf[:]); err != nil {
 			return err
@@ -66,7 +66,7 @@ func loadTSF(filename string) (*FramesContainer, error) {
 	fps := math.Float64frombits(binary.LittleEndian.Uint64(raw[6:]))
 	count := binary.LittleEndian.Uint32(raw[14:])
 
-	frames := make([][]byte, 0, count)
+	colorFrames := make([][]byte, 0, count)
 	off := 18
 	for range count {
 		if off+4 > len(raw) {
@@ -77,15 +77,15 @@ func loadTSF(filename string) (*FramesContainer, error) {
 		if off+n > len(raw) {
 			return nil, invalid()
 		}
-		frames = append(frames, raw[off:off+n])
+		colorFrames = append(colorFrames, raw[off:off+n])
 		off += n
 	}
 
-	if len(frames) == 0 || fps <= 0 {
+	if len(colorFrames) == 0 || fps <= 0 {
 		return nil, fmt.Errorf(
 			"invalid frames file %q: expected non-empty frames and a positive fps",
 			filename,
 		)
 	}
-	return &FramesContainer{Frames: frames, FPS: fps}, nil
+	return &FramesContainer{ColorFrames: colorFrames, FPS: fps}, nil
 }

src/frames.go

@@ -14,11 +14,37 @@ import (
 )
 
 type FramesContainer struct {
-	Frames [][]byte
+	ColorFrames [][]byte
 	FPS         float64
 	Name        string
 }
 
+type colorTier int
+
+const (
+	colorTierNone colorTier = iota
+	colorTier256
+	colorTierTrueColor
+)
+
+func detectColorTier(term string) colorTier {
+	t := strings.ToLower(strings.TrimSpace(term))
+	switch t {
+	case "", "dumb", "vt52", "vt100", "vt102", "vt220", "ansi", "linux", "cons25", "cygwin":
+		return colorTierNone
+	}
+	if strings.Contains(t, "direct") || strings.Contains(t, "truecolor") {
+		return colorTierTrueColor
+	}
+	if strings.Contains(t, "256color") {
+		return colorTier256
+	}
+	if strings.HasPrefix(t, "screen") || strings.HasPrefix(t, "tmux") {
+		return colorTier256
+	}
+	return colorTierTrueColor
+}
+
 var charsetPresets = map[string]string{
 	"detailed": " .'`^\",:;Il!i><~+_-?][}{1)(|/tfjrxnuvczXYUJCLQ0OZmwqpdbkhao*#MW&8%B@$",
 	"standard": " .:-=+*#%@",
@@ -36,14 +62,22 @@ func resolveCharset(charset string) string {
 	return charset
 }
 
-func resizeFrame(frame []byte, width, height int, keepAspectRatio bool) ([]byte, error) {
+func resizeFrame(frame []byte, width, height int, keepAspectRatio bool, tier colorTier) (draw.Image, error) {
 	src, err := jpeg.Decode(bytes.NewReader(frame))
 	if err != nil {
 		return nil, err
 	}
-	dst := image.NewGray(image.Rect(0, 0, width, height))
+	var dst draw.Image
+	var bg color.Color
+	if tier == colorTierNone {
+		dst = image.NewGray(image.Rect(0, 0, width, height))
+		bg = color.Gray{0}
+	} else {
+		dst = image.NewNRGBA(image.Rect(0, 0, width, height))
+		bg = color.Black
+	}
 	if keepAspectRatio {
-		draw.Draw(dst, dst.Bounds(), image.NewUniform(color.Gray{0}), image.Point{}, draw.Src)
+		draw.Draw(dst, dst.Bounds(), image.NewUniform(bg), image.Point{}, draw.Src)
 		sb := src.Bounds()
 		sw, sh := sb.Dx(), sb.Dy()
 		scale := min(float64(width)/float64(sw), float64(height)/float64(sh))
@@ -55,7 +89,7 @@ func resizeFrame(frame []byte, width, height int, keepAspectRatio bool) ([]byte,
 	} else {
 		draw.ApproxBiLinear.Scale(dst, dst.Bounds(), src, src.Bounds(), draw.Src, nil)
 	}
-	return dst.Pix, nil
+	return dst, nil
 }
 
 type asciiOptions struct {
@@ -64,14 +98,9 @@ type asciiOptions struct {
 	invert              bool
 }
 
-func frameToAscii(pixels []byte, options asciiOptions) string {
-	ramp := []rune(resolveCharset(options.charset))
-	total := len(ramp)
-	var b strings.Builder
-	for _, p := range pixels {
-		brightness := int(p) * 100 / 255
+func rampIndex(brightness, threshold, total int, invert bool) int {
 	var index int
-		if brightness < options.brightnessThreshold {
+	if brightness < threshold {
 		index = 0
 	} else {
 		index = brightness * total / 100
@@ -79,16 +108,80 @@ func frameToAscii(pixels []byte, options asciiOptions) string {
 			index = total - 1
 		}
 	}
-		if options.invert {
+	if invert {
 		index = total - 1 - index
 	}
+	return index
+}
+
+func frameToAscii(pixels []byte, options asciiOptions) string {
+	ramp := []rune(resolveCharset(options.charset))
+	total := len(ramp)
+	var b strings.Builder
+	for _, p := range pixels {
+		brightness := int(p) * 100 / 255
+		index := rampIndex(brightness, options.brightnessThreshold, total, options.invert)
 		b.WriteRune(ramp[index])
 	}
 	return b.String()
 }
 
+const ansiReset = "\x1b[0m"
+
+var ansi256Levels = [6]int{0, 95, 135, 175, 215, 255}
+
+func quantize256(r, g, b uint8) int {
+	toLevel := func(v uint8) int {
+		best, bestDist := 0, 1<<30
+		for i, l := range ansi256Levels {
+			d := int(v) - l
+			if d < 0 {
+				d = -d
+			}
+			if d < bestDist {
+				bestDist, best = d, i
+			}
+		}
+		return best
+	}
+	return 16 + 36*toLevel(r) + 6*toLevel(g) + toLevel(b)
+}
+
+func frameToAnsi(img *image.NRGBA, options asciiOptions, tier colorTier) string {
+	ramp := []rune(resolveCharset(options.charset))
+	total := len(ramp)
+	bounds := img.Bounds()
+	var b strings.Builder
+	var lastR, lastG, lastB uint8
+	first := true
+	for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+		for x := bounds.Min.X; x < bounds.Max.X; x++ {
+			o := img.PixOffset(x, y)
+			r, g, bl := img.Pix[o], img.Pix[o+1], img.Pix[o+2]
+			brightness := (int(r)*299 + int(g)*587 + int(bl)*114) / 255 / 10
+			index := rampIndex(brightness, options.brightnessThreshold, total, options.invert)
+			if first || r != lastR || g != lastG || bl != lastB {
+				if tier == colorTierTrueColor {
+					fmt.Fprintf(&b, "\x1b[38;2;%d;%d;%dm", r, g, bl)
+				} else {
+					fmt.Fprintf(&b, "\x1b[38;5;%dm", quantize256(r, g, bl))
+				}
+				lastR, lastG, lastB = r, g, bl
+				first = false
+			}
+			b.WriteRune(ramp[index])
+		}
+		if y < bounds.Max.Y-1 {
+			b.WriteString(ansiReset + "\r\n")
+			first = true
+		}
+	}
+	b.WriteString(ansiReset)
+	return b.String()
+}
+
 type FrameRenderer struct {
-	frames     [][]byte
+	colorFrames [][]byte
 	options     asciiOptions
 	maxEntries  int
 
@@ -102,9 +195,9 @@ type cacheEntry struct {
 	ascii string
 }
 
-func newFrameRenderer(frames [][]byte, options asciiOptions) *FrameRenderer {
+func newFrameRenderer(colorFrames [][]byte, options asciiOptions) *FrameRenderer {
 	return &FrameRenderer{
-		frames:     frames,
+		colorFrames: colorFrames,
 		options:     options,
 		maxEntries:  4096,
 		cache:       make(map[string]*list.Element),
@@ -112,8 +205,8 @@ func newFrameRenderer(frames [][]byte, options asciiOptions) *FrameRenderer {
 	}
 }
 
-func (r *FrameRenderer) render(index, width, height int, keepAspectRatio bool) (string, error) {
-	key := fmt.Sprintf("%d:%dx%d:%t", index, width, height, keepAspectRatio)
+func (r *FrameRenderer) render(index, width, height int, keepAspectRatio bool, tier colorTier) (string, error) {
+	key := fmt.Sprintf("%d:%dx%d:%t:%d", index, width, height, keepAspectRatio, tier)
 
 	r.mu.Lock()
 	if el, ok := r.cache[key]; ok {
@@ -124,11 +217,20 @@ func (r *FrameRenderer) render(index, width, height int, keepAspectRatio bool) (
 	}
 	r.mu.Unlock()
 
-	pixels, err := resizeFrame(r.frames[index], width, height, keepAspectRatio)
+	var ascii string
+	if tier == colorTierNone {
+		img, err := resizeFrame(r.colorFrames[index], width, height, keepAspectRatio, tier)
 		if err != nil {
 			return "", err
 		}
-	ascii := frameToAscii(pixels, r.options)
+		ascii = frameToAscii(img.(*image.Gray).Pix, r.options)
+	} else {
+		img, err := resizeFrame(r.colorFrames[index], width, height, keepAspectRatio, tier)
+		if err != nil {
+			return "", err
+		}
+		ascii = frameToAnsi(img.(*image.NRGBA), r.options, tier)
+	}
 
 	r.mu.Lock()
 	if _, ok := r.cache[key]; !ok {

src/main.go

@@ -122,7 +122,7 @@ func loadAllFrames(framesDir string) []*FramesContainer {
 				return
 			}
 			data.Name = file
-			logInfo(fmt.Sprintf("  %s: %d frames @ %gfps", file, len(data.Frames), data.FPS))
+			logInfo(fmt.Sprintf("  %s: %d frames @ %gfps", file, len(data.ColorFrames), data.FPS))
 			results[i] = data
 		}
 	}

src/server.go

@@ -102,7 +102,7 @@ func createServer(deps ServerDeps) *Server {
 	for i, data := range deps.VideoSets {
 		sets[i] = frameSet{
 			data: data,
-			renderer: newFrameRenderer(data.Frames, asciiOptions{
+			renderer: newFrameRenderer(data.ColorFrames, asciiOptions{
 				brightnessThreshold: config.BrightnessThreshold,
 				charset:             config.Charset,
 				invert:              config.Invert,
@@ -277,6 +277,18 @@ func parseDims(payload []byte) (cols, rows int, ok bool) {
 	return cols, rows, true
 }
 
+// parsePtyTerm extracts the TERM string prefixing a pty-req payload.
+func parsePtyTerm(payload []byte) (term string, ok bool) {
+	if len(payload) < 4 {
+		return "", false
+	}
+	strLen := binary.BigEndian.Uint32(payload)
+	if int(strLen)+16 > len(payload) {
+		return "", false
+	}
+	return string(payload[4 : 4+strLen]), true
+}
+
 func (s *Server) handleSession(
 	sshConn *ssh.ServerConn,
 	channel ssh.Channel,
@@ -286,6 +298,10 @@ func (s *Server) handleSession(
 ) {
 	size := &termSize{}
 	size.set(80, 24, s.config.MaxDimension)
+	tier := colorTierTrueColor
+	if s.config.ForceGrayscale {
+		tier = colorTierNone
+	}
 
 	started := false
 	for req := range requests {
@@ -295,6 +311,13 @@ func (s *Server) handleSession(
 			if cols, rows, ok := parseDims(req.Payload); ok {
 				size.set(cols, rows, s.config.MaxDimension)
 			}
+			if term, ok := parsePtyTerm(req.Payload); ok {
+				tier = detectColorTier(term)
+				if s.config.ForceGrayscale {
+					tier = colorTierNone
+				}
+				logDebug(fmt.Sprintf("Client %s TERM=%q -> color tier %d", ip, sanitizeN(term, 64), tier))
+			}
 			req.Reply(true, nil)
 		case "window-change":
 			if len(req.Payload) >= 8 {
@@ -317,14 +340,14 @@ func (s *Server) handleSession(
 			req.Reply(true, nil)
 			if !started {
 				started = true
-				go s.playVideo(sshConn, channel, size, ip, initialSetIndex, false)
+				go s.playVideo(sshConn, channel, size, ip, initialSetIndex, false, tier)
 			}
 		case "shell":
 			logDebug("Opening shell for session", ip)
 			req.Reply(true, nil)
 			if !started {
 				started = true
-				go s.playVideo(sshConn, channel, size, ip, initialSetIndex, false)
+				go s.playVideo(sshConn, channel, size, ip, initialSetIndex, false, tier)
 			}
 		default:
 			if req.WantReply {
@@ -352,6 +375,7 @@ func (s *Server) playVideo(
 	ip string,
 	setIndex int,
 	keepAspectRatio bool,
+	tier colorTier,
 ) {
 	config := s.config
 	current := s.sets[setIndex]
@@ -438,7 +462,7 @@ func (s *Server) playVideo(
 
 		case <-ticker.C:
 			w, h := size.get()
-			ascii, err := current.renderer.render(currentFrame, w, h, keepAspectRatio)
+			ascii, err := current.renderer.render(currentFrame, w, h, keepAspectRatio, tier)
 			if err != nil {
 				logError("Render error for", ip, sanitize(err.Error()))
 				sshConn.Close()
@@ -451,7 +475,7 @@ func (s *Server) playVideo(
 			}
 
 			currentFrame++
-			if currentFrame < len(current.data.Frames) {
+			if currentFrame < len(current.data.ColorFrames) {
 				continue
 			}
 

src/videoprocessor.go

@@ -72,6 +72,61 @@ func parseFrameRate(rate string) float64 {
 	return num
 }
 
+func extractFrames(path, vf, label string, maxDimension, totalFrames int) ([][]byte, error) {
+	cmd := exec.Command(
+		"ffmpeg", "-i", path,
+		"-c:v", "mjpeg",
+		"-q:v", "3",
+		"-vf", vf,
+		"-f", "image2pipe",
+		"pipe:1",
+	)
+	var stderr bytes.Buffer
+	cmd.Stderr = &stderr
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, fmt.Errorf("ffmpeg failed: %w", err)
+	}
+	if err := cmd.Start(); err != nil {
+		return nil, fmt.Errorf("ffmpeg failed: %w", err)
+	}
+
+	var frames [][]byte
+	splitter := &jpegFrameSplitter{}
+	reportProgress := func(count int) {
+		if totalFrames > 0 {
+			pct := min(100, int(math.Round(float64(count)/float64(totalFrames)*100)))
+			fmt.Printf("\rGenerating %s frames: %d/%d (%d%%)", label, count, totalFrames, pct)
+		} else {
+			fmt.Printf("\rGenerating %s frames: %d", label, count)
+		}
+	}
+
+	buf := make([]byte, 256*1024)
+	for {
+		n, err := stdout.Read(buf)
+		if n > 0 {
+			frames = append(frames, splitter.push(buf[:n])...)
+			reportProgress(len(frames))
+		}
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			cmd.Wait()
+			return nil, fmt.Errorf("ffmpeg stream error: %s", err.Error())
+		}
+	}
+	if err := cmd.Wait(); err != nil {
+		return nil, fmt.Errorf("ffmpeg failed: %s", strings.TrimSpace(stderr.String()))
+	}
+	if len(frames) == 0 {
+		return nil, fmt.Errorf("no frames were decoded from the video")
+	}
+	fmt.Println()
+	return frames, nil
+}
+
 func processVideo(path, output string, maxDimension int) error {
 	probeCmd := exec.Command(
 		"ffprobe", "-v", "error",
@@ -115,65 +170,20 @@ func processVideo(path, output string, maxDimension int) error {
 		}
 	}
 
-	vf := fmt.Sprintf(
-		"format=gray,scale=w=%d:h=%d:force_original_aspect_ratio=decrease",
+	scaleFilter := fmt.Sprintf(
+		"scale=w=%d:h=%d:force_original_aspect_ratio=decrease",
 		maxDimension, maxDimension,
 	)
-	cmd := exec.Command(
-		"ffmpeg", "-i", path,
-		"-c:v", "mjpeg",
-		"-q:v", "3",
-		"-vf", vf,
-		"-f", "image2pipe",
-		"pipe:1",
-	)
-	var stderr bytes.Buffer
-	cmd.Stderr = &stderr
-	stdout, err := cmd.StdoutPipe()
+
+	colorFrames, err := extractFrames(path, scaleFilter, "color", maxDimension, totalFrames)
 	if err != nil {
-		return fmt.Errorf("ffmpeg failed: %w", err)
-	}
-	if err := cmd.Start(); err != nil {
-		return fmt.Errorf("ffmpeg failed: %w", err)
+		return err
 	}
 
-	videoData := FramesContainer{FPS: fps}
-	splitter := &jpegFrameSplitter{}
-	reportProgress := func(count int) {
-		if totalFrames > 0 {
-			pct := min(100, int(math.Round(float64(count)/float64(totalFrames)*100)))
-			fmt.Printf("\rGenerating frames: %d/%d (%d%%)", count, totalFrames, pct)
-		} else {
-			fmt.Printf("\rGenerating frames: %d", count)
-		}
-	}
-
-	buf := make([]byte, 256*1024)
-	for {
-		n, err := stdout.Read(buf)
-		if n > 0 {
-			videoData.Frames = append(videoData.Frames, splitter.push(buf[:n])...)
-			reportProgress(len(videoData.Frames))
-		}
-		if err == io.EOF {
-			break
-		}
-		if err != nil {
-			cmd.Wait()
-			return fmt.Errorf("ffmpeg stream error: %s", err.Error())
-		}
-	}
-	if err := cmd.Wait(); err != nil {
-		return fmt.Errorf("ffmpeg failed: %s", strings.TrimSpace(stderr.String()))
-	}
-	if len(videoData.Frames) == 0 {
-		return fmt.Errorf("no frames were decoded from the video")
-	}
-
-	fmt.Println()
+	videoData := FramesContainer{FPS: fps, ColorFrames: colorFrames}
 	if err := writeTSF(output, &videoData); err != nil {
 		return err
 	}
-	logInfo(fmt.Sprintf("Saved %d frames to %s", len(videoData.Frames), output))
+	logInfo(fmt.Sprintf("Saved %d frames to %s", len(videoData.ColorFrames), output))
 	return nil
 }