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import {
Input,
ALL_FORMATS,
BlobSource,
CanvasSink,
WrappedCanvas,
} from "mediabunny";
interface VideoSinkData {
sink: CanvasSink;
iterator: AsyncGenerator<WrappedCanvas, void, unknown> | null;
currentFrame: WrappedCanvas | null;
lastTime: number;
}
export class VideoCache {
private sinks = new Map<string, VideoSinkData>();
private initPromises = new Map<string, Promise<void>>();
async getFrameAt(
mediaId: string,
file: File,
time: number
): Promise<WrappedCanvas | null> {
await this.ensureSink(mediaId, file);
const sinkData = this.sinks.get(mediaId);
if (!sinkData) return null;
if (
sinkData.currentFrame &&
this.isFrameValid(sinkData.currentFrame, time)
) {
return sinkData.currentFrame;
}
if (
sinkData.iterator &&
sinkData.currentFrame &&
time >= sinkData.lastTime &&
time < sinkData.lastTime + 2.0
) {
const frame = await this.iterateToTime(sinkData, time);
if (frame) return frame;
}
return await this.seekToTime(sinkData, time);
}
private isFrameValid(frame: WrappedCanvas, time: number): boolean {
return time >= frame.timestamp && time < frame.timestamp + frame.duration;
}
private async iterateToTime(
sinkData: VideoSinkData,
targetTime: number
): Promise<WrappedCanvas | null> {
if (!sinkData.iterator) return null;
try {
while (true) {
const { value: frame, done } = await sinkData.iterator.next();
if (done || !frame) break;
sinkData.currentFrame = frame;
sinkData.lastTime = frame.timestamp;
if (this.isFrameValid(frame, targetTime)) {
return frame;
}
if (frame.timestamp > targetTime + 1.0) break;
}
} catch (error) {
console.warn("Iterator failed, will restart:", error);
sinkData.iterator = null;
}
return null;
}
private async seekToTime(
sinkData: VideoSinkData,
time: number
): Promise<WrappedCanvas | null> {
try {
if (sinkData.iterator) {
await sinkData.iterator.return();
sinkData.iterator = null;
}
sinkData.iterator = sinkData.sink.canvases(time);
sinkData.lastTime = time;
const { value: frame } = await sinkData.iterator.next();
if (frame) {
sinkData.currentFrame = frame;
return frame;
}
} catch (error) {
console.warn("Failed to seek video:", error);
}
return null;
}
private async ensureSink(mediaId: string, file: File): Promise<void> {
if (this.sinks.has(mediaId)) return;
if (this.initPromises.has(mediaId)) {
await this.initPromises.get(mediaId);
return;
}
const initPromise = this.initializeSink(mediaId, file);
this.initPromises.set(mediaId, initPromise);
try {
await initPromise;
} finally {
this.initPromises.delete(mediaId);
}
}
private async initializeSink(mediaId: string, file: File): Promise<void> {
try {
const input = new Input({
source: new BlobSource(file),
formats: ALL_FORMATS,
});
const videoTrack = await input.getPrimaryVideoTrack();
if (!videoTrack) {
throw new Error("No video track found");
}
const canDecode = await videoTrack.canDecode();
if (!canDecode) {
throw new Error("Video codec not supported for decoding");
}
const sink = new CanvasSink(videoTrack, {
poolSize: 3,
fit: "contain",
});
this.sinks.set(mediaId, {
sink,
iterator: null,
currentFrame: null,
lastTime: -1,
});
} catch (error) {
console.error(`Failed to initialize video sink for ${mediaId}:`, error);
throw error;
}
}
clearVideo(mediaId: string): void {
const sinkData = this.sinks.get(mediaId);
if (sinkData) {
if (sinkData.iterator) {
sinkData.iterator.return();
}
this.sinks.delete(mediaId);
}
this.initPromises.delete(mediaId);
}
clearAll(): void {
for (const [mediaId] of this.sinks) {
this.clearVideo(mediaId);
}
}
getStats() {
return {
totalSinks: this.sinks.size,
activeSinks: Array.from(this.sinks.values()).filter((s) => s.iterator)
.length,
cachedFrames: Array.from(this.sinks.values()).filter(
(s) => s.currentFrame
).length,
};
}
}
export const videoCache = new VideoCache();
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