feat: add frame rate selector for MP4 export (24/30/60 FPS)

  Adds a 3-button FPS toggle (24 / 30 / 60) to the MP4 export panel,
  directly below the existing quality selector. The selected frame rate
  replaces the previously hardcoded 60 FPS value and is persisted to
  user preferences and project files.

  - Add Mp4FrameRate type and MP4_FRAME_RATES constant to exporter types
  - Add mp4FrameRate to UserPreferences and ProjectEditorState
  - Wire state, persistence, and export config in VideoEditor
  - Add FPS button row UI in SettingsPanel matching the GIF FPS pattern
  - Add mp4Settings.frameRate i18n key to all 5 locale files

Author: Scottlexium

src/components/video-editor/SettingsPanel.tsx

@@ -36,8 +36,14 @@ import { Tabs, TabsContent, TabsList, TabsTrigger } from "@/components/ui/tabs";
 import { useScopedT } from "@/contexts/I18nContext";
 import { getAssetPath } from "@/lib/assetPath";
 import { WEBCAM_LAYOUT_PRESETS } from "@/lib/compositeLayout";
-import type { ExportFormat, ExportQuality, GifFrameRate, GifSizePreset } from "@/lib/exporter";
-import { GIF_FRAME_RATES, GIF_SIZE_PRESETS } from "@/lib/exporter";
+import type {
+	ExportFormat,
+	ExportQuality,
+	GifFrameRate,
+	GifSizePreset,
+	Mp4FrameRate,
+} from "@/lib/exporter";
+import { GIF_FRAME_RATES, GIF_SIZE_PRESETS, MP4_FRAME_RATES } from "@/lib/exporter";
 import { cn } from "@/lib/utils";
 import { type AspectRatio, isPortraitAspectRatio } from "@/utils/aspectRatioUtils";
 import { getTestId } from "@/utils/getTestId";
@@ -188,6 +194,8 @@ interface SettingsPanelProps {
 	// Export format settings
 	exportFormat?: ExportFormat;
 	onExportFormatChange?: (format: ExportFormat) => void;
+	mp4FrameRate?: Mp4FrameRate;
+	onMp4FrameRateChange?: (rate: Mp4FrameRate) => void;
 	gifFrameRate?: GifFrameRate;
 	onGifFrameRateChange?: (rate: GifFrameRate) => void;
 	gifLoop?: boolean;
@@ -268,6 +276,8 @@ export function SettingsPanel({
 	onExportQualityChange,
 	exportFormat = "mp4",
 	onExportFormatChange,
+	mp4FrameRate = 60,
+	onMp4FrameRateChange,
 	gifFrameRate = 15,
 	onGifFrameRateChange,
 	gifLoop = true,
@@ -1306,40 +1316,58 @@ export function SettingsPanel({
 				</div>
 
 				{exportFormat === "mp4" && (
-					<div className="mb-3 bg-white/5 border border-white/5 p-0.5 w-full grid grid-cols-3 h-7 rounded-lg">
-						<button
-							onClick={() => onExportQualityChange?.("medium")}
-							className={cn(
-								"rounded-md transition-all text-[10px] font-medium",
-								exportQuality === "medium"
-									? "bg-white text-black"
-									: "text-slate-400 hover:text-slate-200",
-							)}
-						>
-							{t("exportQuality.low")}
-						</button>
-						<button
-							onClick={() => onExportQualityChange?.("good")}
-							className={cn(
-								"rounded-md transition-all text-[10px] font-medium",
-								exportQuality === "good"
-									? "bg-white text-black"
-									: "text-slate-400 hover:text-slate-200",
-							)}
-						>
-							{t("exportQuality.medium")}
-						</button>
-						<button
-							onClick={() => onExportQualityChange?.("source")}
-							className={cn(
-								"rounded-md transition-all text-[10px] font-medium",
-								exportQuality === "source"
-									? "bg-white text-black"
-									: "text-slate-400 hover:text-slate-200",
-							)}
-						>
-							{t("exportQuality.high")}
-						</button>
+					<div className="mb-3 space-y-1.5">
+						<div className="bg-white/5 border border-white/5 p-0.5 w-full grid grid-cols-3 h-7 rounded-lg">
+							<button
+								onClick={() => onExportQualityChange?.("medium")}
+								className={cn(
+									"rounded-md transition-all text-[10px] font-medium",
+									exportQuality === "medium"
+										? "bg-white text-black"
+										: "text-slate-400 hover:text-slate-200",
+								)}
+							>
+								{t("exportQuality.low")}
+							</button>
+							<button
+								onClick={() => onExportQualityChange?.("good")}
+								className={cn(
+									"rounded-md transition-all text-[10px] font-medium",
+									exportQuality === "good"
+										? "bg-white text-black"
+										: "text-slate-400 hover:text-slate-200",
+								)}
+							>
+								{t("exportQuality.medium")}
+							</button>
+							<button
+								onClick={() => onExportQualityChange?.("source")}
+								className={cn(
+									"rounded-md transition-all text-[10px] font-medium",
+									exportQuality === "source"
+										? "bg-white text-black"
+										: "text-slate-400 hover:text-slate-200",
+								)}
+							>
+								{t("exportQuality.high")}
+							</button>
+						</div>
+						<div className="bg-white/5 border border-white/5 p-0.5 w-full grid grid-cols-3 h-7 rounded-lg">
+							{MP4_FRAME_RATES.map((rate) => (
+								<button
+									key={rate.value}
+									onClick={() => onMp4FrameRateChange?.(rate.value)}
+									className={cn(
+										"rounded-md transition-all text-[10px] font-medium",
+										mp4FrameRate === rate.value
+											? "bg-white text-black"
+											: "text-slate-400 hover:text-slate-200",
+									)}
+								>
+									{rate.value}
+								</button>
+							))}
+						</div>
 					</div>
 				)}
 

src/components/video-editor/VideoEditor.tsx

@@ -26,6 +26,7 @@ import {
 	GifExporter,
 	type GifFrameRate,
 	type GifSizePreset,
+	type Mp4FrameRate,
 	VideoExporter,
 } from "@/lib/exporter";
 import { computeFrameStepTime } from "@/lib/frameStep";
@@ -129,6 +130,7 @@ export default function VideoEditor() {
 	const [showNewRecordingDialog, setShowNewRecordingDialog] = useState(false);
 	const [exportQuality, setExportQuality] = useState<ExportQuality>("good");
 	const [exportFormat, setExportFormat] = useState<ExportFormat>("mp4");
+	const [mp4FrameRate, setMp4FrameRate] = useState<Mp4FrameRate>(60);
 	const [gifFrameRate, setGifFrameRate] = useState<GifFrameRate>(15);
 	const [gifLoop, setGifLoop] = useState(true);
 	const [gifSizePreset, setGifSizePreset] = useState<GifSizePreset>("medium");
@@ -221,6 +223,7 @@ export default function VideoEditor() {
 			});
 			setExportQuality(normalizedEditor.exportQuality);
 			setExportFormat(normalizedEditor.exportFormat);
+			setMp4FrameRate(normalizedEditor.mp4FrameRate);
 			setGifFrameRate(normalizedEditor.gifFrameRate);
 			setGifLoop(normalizedEditor.gifLoop);
 			setGifSizePreset(normalizedEditor.gifSizePreset);
@@ -287,6 +290,7 @@ export default function VideoEditor() {
 			webcamPosition,
 			exportQuality,
 			exportFormat,
+			mp4FrameRate,
 			gifFrameRate,
 			gifLoop,
 			gifSizePreset,
@@ -307,10 +311,10 @@ export default function VideoEditor() {
 		aspectRatio,
 		webcamLayoutPreset,
 		webcamMaskShape,
-		webcamSizePreset,
 		webcamPosition,
 		exportQuality,
 		exportFormat,
+		mp4FrameRate,
 		gifFrameRate,
 		gifLoop,
 		gifSizePreset,
@@ -392,14 +396,15 @@ export default function VideoEditor() {
 		});
 		setExportQuality(prefs.exportQuality);
 		setExportFormat(prefs.exportFormat);
+		setMp4FrameRate(prefs.mp4FrameRate);
 		setPrefsHydrated(true);
 	}, [updateState]);
 
 	// Auto-save user preferences when settings change
 	useEffect(() => {
 		if (!prefsHydrated) return;
-		saveUserPreferences({ padding, aspectRatio, exportQuality, exportFormat });
-	}, [prefsHydrated, padding, aspectRatio, exportQuality, exportFormat]);
+		saveUserPreferences({ padding, aspectRatio, exportQuality, exportFormat, mp4FrameRate });
+	}, [prefsHydrated, padding, aspectRatio, exportQuality, exportFormat, mp4FrameRate]);
 
 	const saveProject = useCallback(
 		async (forceSaveAs: boolean) => {
@@ -432,6 +437,7 @@ export default function VideoEditor() {
 				webcamPosition,
 				exportQuality,
 				exportFormat,
+				mp4FrameRate,
 				gifFrameRate,
 				gifLoop,
 				gifSizePreset,
@@ -488,6 +494,7 @@ export default function VideoEditor() {
 			webcamPosition,
 			exportQuality,
 			exportFormat,
+			mp4FrameRate,
 			gifFrameRate,
 			gifLoop,
 			gifSizePreset,
@@ -1339,7 +1346,7 @@ export default function VideoEditor() {
 						webcamVideoUrl: webcamVideoPath || undefined,
 						width: exportWidth,
 						height: exportHeight,
-						frameRate: 60,
+						frameRate: mp4FrameRate,
 						bitrate,
 						codec: "avc1.640033",
 						wallpaper,
@@ -1430,6 +1437,7 @@ export default function VideoEditor() {
 			webcamSizePreset,
 			webcamPosition,
 			exportQuality,
+			mp4FrameRate,
 			handleExportSaved,
 			cursorTelemetry,
 		],
@@ -1809,6 +1817,8 @@ export default function VideoEditor() {
 						onExportQualityChange={setExportQuality}
 						exportFormat={exportFormat}
 						onExportFormatChange={setExportFormat}
+						mp4FrameRate={mp4FrameRate}
+						onMp4FrameRateChange={setMp4FrameRate}
 						gifFrameRate={gifFrameRate}
 						onGifFrameRateChange={setGifFrameRate}
 						gifLoop={gifLoop}

src/components/video-editor/projectPersistence.ts

@@ -1,4 +1,10 @@
-import type { ExportFormat, ExportQuality, GifFrameRate, GifSizePreset } from "@/lib/exporter";
+import type {
+	ExportFormat,
+	ExportQuality,
+	GifFrameRate,
+	GifSizePreset,
+	Mp4FrameRate,
+} from "@/lib/exporter";
 import type { ProjectMedia } from "@/lib/recordingSession";
 import { normalizeProjectMedia } from "@/lib/recordingSession";
 import { ASPECT_RATIOS, type AspectRatio } from "@/utils/aspectRatioUtils";
@@ -56,6 +62,7 @@ export interface ProjectEditorState {
 	webcamPosition: WebcamPosition | null;
 	exportQuality: ExportQuality;
 	exportFormat: ExportFormat;
+	mp4FrameRate: Mp4FrameRate;
 	gifFrameRate: GifFrameRate;
 	gifLoop: boolean;
 	gifSizePreset: GifSizePreset;
@@ -384,6 +391,10 @@ export function normalizeProjectEditor(editor: Partial<ProjectEditorState>): Pro
 				? editor.exportQuality
 				: "good",
 		exportFormat: editor.exportFormat === "gif" ? "gif" : "mp4",
+		mp4FrameRate:
+			editor.mp4FrameRate === 24 || editor.mp4FrameRate === 30 || editor.mp4FrameRate === 60
+				? editor.mp4FrameRate
+				: 60,
 		gifFrameRate:
 			editor.gifFrameRate === 15 ||
 			editor.gifFrameRate === 20 ||

src/i18n/locales/en/settings.json

@@ -70,6 +70,9 @@
 		"medium": "Medium",
 		"high": "High"
 	},
+	"mp4Settings": {
+		"frameRate": "Frame Rate"
+	},
 	"gifSettings": {
 		"frameRate": "GIF Frame Rate",
 		"size": "GIF Size",

src/i18n/locales/es/settings.json

@@ -70,6 +70,9 @@
 		"medium": "Media",
 		"high": "Alta"
 	},
+	"mp4Settings": {
+		"frameRate": "Frecuencia de fotogramas"
+	},
 	"gifSettings": {
 		"frameRate": "Velocidad de cuadros del GIF",
 		"size": "Tamaño del GIF",

src/i18n/locales/fr/settings.json

@@ -67,6 +67,9 @@
 		"medium": "Moyenne",
 		"high": "Haute"
 	},
+	"mp4Settings": {
+		"frameRate": "Fréquence d'images"
+	},
 	"gifSettings": {
 		"frameRate": "Fréquence d'images GIF",
 		"size": "Taille du GIF",

src/i18n/locales/tr/settings.json

@@ -67,6 +67,9 @@
 		"medium": "Orta",
 		"high": "Yüksek"
 	},
+	"mp4Settings": {
+		"frameRate": "Kare Hızı"
+	},
 	"gifSettings": {
 		"frameRate": "GIF Kare Hızı",
 		"size": "GIF Boyutu",

src/i18n/locales/zh-CN/settings.json

@@ -70,6 +70,9 @@
 		"medium": "中",
 		"high": "高"
 	},
+	"mp4Settings": {
+		"frameRate": "帧率"
+	},
 	"gifSettings": {
 		"frameRate": "GIF 帧率",
 		"size": "GIF 尺寸",

src/lib/exporter/index.ts

@@ -12,13 +12,17 @@ export type {
 	GifExportConfig,
 	GifFrameRate,
 	GifSizePreset,
+	Mp4FrameRate,
 	VideoFrameData,
 } from "./types";
 export {
 	GIF_FRAME_RATES,
 	GIF_SIZE_PRESETS,
 	isValidGifFrameRate,
+	isValidMp4FrameRate,
+	MP4_FRAME_RATES,
 	VALID_GIF_FRAME_RATES,
+	VALID_MP4_FRAME_RATES,
 } from "./types";
 export { VideoFileDecoder } from "./videoDecoder";
 export { VideoExporter } from "./videoExporter";

src/lib/exporter/types.ts

@@ -34,6 +34,8 @@ export type ExportFormat = "mp4" | "gif";
 
 export type GifFrameRate = 15 | 20 | 25 | 30;
 
+export type Mp4FrameRate = 24 | 30 | 60;
+
 export type GifSizePreset = "medium" | "large" | "original";
 
 export interface GifExportConfig {
@@ -58,6 +60,26 @@ export const GIF_SIZE_PRESETS: Record<GifSizePreset, { maxHeight: number; label:
 	original: { maxHeight: Infinity, label: "Original" },
 };
 
+/** Display metadata for each supported MP4 frame rate option. */
+export const MP4_FRAME_RATES: { value: Mp4FrameRate; label: string }[] = [
+	{ value: 24, label: "24 FPS" },
+	{ value: 30, label: "30 FPS" },
+	{ value: 60, label: "60 FPS" },
+];
+
+/** Tuple of every valid MP4 frame rate value used for runtime validation. */
+export const VALID_MP4_FRAME_RATES: readonly Mp4FrameRate[] = [24, 30, 60] as const;
+
+/**
+ * Type guard that checks whether a number is a valid {@link Mp4FrameRate}.
+ *
+ * @param rate - The frame rate value to test.
+ * @returns `true` if `rate` is 24, 30, or 60; `false` otherwise.
+ */
+export function isValidMp4FrameRate(rate: number): rate is Mp4FrameRate {
+	return VALID_MP4_FRAME_RATES.includes(rate as Mp4FrameRate);
+}
+
 export const GIF_FRAME_RATES: { value: GifFrameRate; label: string }[] = [
 	{ value: 15, label: "15 FPS - Balanced" },
 	{ value: 20, label: "20 FPS - Smooth" },