2 files changed, 153 insertions, 2 deletions
diff --git a/apps/web/src/lib/export.ts b/apps/web/src/lib/export.ts
new file mode 100644
index 00000000..69bc8d1d
--- /dev/null
+++ b/apps/web/src/lib/export.ts
@@ -0,0 +1,147 @@
+import {
+  Output,
+  Mp4OutputFormat,
+  WebMOutputFormat,
+  BufferTarget,
+  CanvasSource,
+  QUALITY_LOW,
+  QUALITY_MEDIUM,
+  QUALITY_HIGH,
+  QUALITY_VERY_HIGH,
+} from "mediabunny";
+import { renderTimelineFrame } from "./timeline-renderer";
+import { useTimelineStore } from "@/stores/timeline-store";
+import { useMediaStore } from "@/stores/media-store";
+import { useProjectStore } from "@/stores/project-store";
+import { DEFAULT_FPS } from "@/stores/project-store";
+import { ExportOptions, ExportResult } from "@/types/export";
+
+export const DEFAULT_EXPORT_OPTIONS: ExportOptions = {
+  format: "mp4",
+  quality: "high",
+};
+
+const qualityMap = {
+  low: QUALITY_LOW,
+  medium: QUALITY_MEDIUM,
+  high: QUALITY_HIGH,
+  very_high: QUALITY_VERY_HIGH,
+};
+
+export async function exportProject(
+  options: ExportOptions
+): Promise<ExportResult> {
+  const { format, quality, fps, onProgress, onCancel } = options;
+
+  try {
+    const timelineStore = useTimelineStore.getState();
+    const mediaStore = useMediaStore.getState();
+    const projectStore = useProjectStore.getState();
+
+    const { tracks, getTotalDuration } = timelineStore;
+    const { mediaFiles } = mediaStore;
+    const { activeProject } = projectStore;
+
+    if (!activeProject) {
+      return { success: false, error: "No active project" };
+    }
+
+    const duration = getTotalDuration();
+    if (duration === 0) {
+      return { success: false, error: "Project is empty" };
+    }
+
+    const exportFps = fps || activeProject.fps || DEFAULT_FPS;
+    const canvasSize = activeProject.canvasSize;
+
+    const outputFormat =
+      format === "webm" ? new WebMOutputFormat() : new Mp4OutputFormat();
+
+    // BufferTarget for smaller files, StreamTarget for larger ones
+    // TODO: Implement StreamTarget
+    const output = new Output({
+      format: outputFormat,
+      target: new BufferTarget(),
+    });
+
+    // Canvas for rendering
+    const canvas = document.createElement("canvas");
+    canvas.width = canvasSize.width;
+    canvas.height = canvasSize.height;
+    const ctx = canvas.getContext("2d");
+
+    if (!ctx) {
+      return { success: false, error: "Failed to create canvas context" };
+    }
+
+    const videoSource = new CanvasSource(canvas, {
+      codec: format === "webm" ? "vp9" : "avc", // VP9 for WebM, H.264 for MP4
+      bitrate: qualityMap[quality],
+    });
+
+    output.addVideoTrack(videoSource, { frameRate: exportFps });
+
+    // Start the output
+    await output.start();
+
+    const totalFrames = Math.ceil(duration * exportFps);
+    let cancelled = false;
+
+    // Render each frame
+    for (let frameIndex = 0; frameIndex < totalFrames; frameIndex++) {
+      // Check for cancellation
+      if (onCancel?.()) {
+        cancelled = true;
+        break;
+      }
+
+      const time = frameIndex / exportFps;
+
+      await renderTimelineFrame({
+        ctx,
+        time,
+        canvasWidth: canvas.width,
+        canvasHeight: canvas.height,
+        tracks,
+        mediaFiles,
+        backgroundColor:
+          activeProject.backgroundType === "blur"
+            ? "transparent"
+            : activeProject.backgroundColor || "#000000",
+        projectCanvasSize: canvasSize,
+      });
+
+      const frameDuration = 1 / exportFps;
+      await videoSource.add(time, frameDuration);
+
+      onProgress?.(frameIndex / totalFrames);
+    }
+
+    if (cancelled) {
+      await output.cancel();
+      return { success: false, cancelled: true };
+    }
+    videoSource.close();
+    await output.finalize();
+    onProgress?.(1);
+
+    return {
+      success: true,
+      buffer: output.target.buffer || undefined,
+    };
+  } catch (error) {
+    console.error("Export failed:", error);
+    return {
+      success: false,
+      error: error instanceof Error ? error.message : "Unknown export error",
+    };
+  }
+}
+
+export function getExportMimeType(format: "mp4" | "webm"): string {
+  return format === "webm" ? "video/webm" : "video/mp4";
+}
+
+export function getExportFileExtension(format: "mp4" | "webm"): string {
+  return `.${format}`;
+}
diff --git a/apps/web/src/lib/timeline-renderer.ts b/apps/web/src/lib/timeline-renderer.ts
index 06825896..6241a7d9 100644
--- a/apps/web/src/lib/timeline-renderer.ts
+++ b/apps/web/src/lib/timeline-renderer.ts
@@ -10,6 +10,7 @@ export interface RenderContext {
   tracks: TimelineTrack[];
   mediaFiles: MediaFile[];
   backgroundColor?: string;
+  projectCanvasSize?: { width: number; height: number };
 }
 
 export async function renderTimelineFrame({
@@ -20,6 +21,7 @@ export async function renderTimelineFrame({
   tracks,
   mediaFiles,
   backgroundColor,
+  projectCanvasSize,
 }: RenderContext): Promise<void> {
   // Background
   ctx.clearRect(0, 0, canvasWidth, canvasHeight);
@@ -28,8 +30,10 @@ export async function renderTimelineFrame({
     ctx.fillRect(0, 0, canvasWidth, canvasHeight);
   }
 
-  const scaleX = 1;
-  const scaleY = 1;
+  const scaleX = projectCanvasSize ? canvasWidth / projectCanvasSize.width : 1;
+  const scaleY = projectCanvasSize
+    ? canvasHeight / projectCanvasSize.height
+    : 1;
   const idToMedia = new Map(mediaFiles.map((m) => [m.id, m] as const));
   const active: Array<{
     track: TimelineTrack;