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import EventEmitter from "eventemitter3";
import {
Output,
Mp4OutputFormat,
WebMOutputFormat,
BufferTarget,
CanvasSource,
AudioBufferSource,
QUALITY_LOW,
QUALITY_MEDIUM,
QUALITY_HIGH,
QUALITY_VERY_HIGH,
} from "mediabunny";
import type { RootNode } from "./nodes/root-node";
import type { ExportFormat, ExportQuality } from "@/types/export";
import { CanvasRenderer } from "./canvas-renderer";
type ExportParams = {
width: number;
height: number;
fps: number;
format: ExportFormat;
quality: ExportQuality;
shouldIncludeAudio?: boolean;
audioBuffer?: AudioBuffer;
};
const qualityMap = {
low: QUALITY_LOW,
medium: QUALITY_MEDIUM,
high: QUALITY_HIGH,
very_high: QUALITY_VERY_HIGH,
};
export type SceneExporterEvents = {
progress: [progress: number];
complete: [buffer: ArrayBuffer];
error: [error: Error];
cancelled: [];
};
export class SceneExporter extends EventEmitter<SceneExporterEvents> {
private renderer: CanvasRenderer;
private format: ExportFormat;
private quality: ExportQuality;
private shouldIncludeAudio: boolean;
private audioBuffer?: AudioBuffer;
private isCancelled = false;
constructor({
width,
height,
fps,
format,
quality,
shouldIncludeAudio,
audioBuffer,
}: ExportParams) {
super();
this.renderer = new CanvasRenderer({
width,
height,
fps,
});
this.format = format;
this.quality = quality;
this.shouldIncludeAudio = shouldIncludeAudio ?? false;
this.audioBuffer = audioBuffer;
}
cancel(): void {
this.isCancelled = true;
}
async export({
rootNode,
}: {
rootNode: RootNode;
}): Promise<ArrayBuffer | null> {
const { fps } = this.renderer;
const frameCount = Math.ceil(rootNode.duration * fps);
const outputFormat =
this.format === "webm" ? new WebMOutputFormat() : new Mp4OutputFormat();
const output = new Output({
format: outputFormat,
target: new BufferTarget(),
});
const videoSource = new CanvasSource(this.renderer.canvas, {
codec: this.format === "webm" ? "vp9" : "avc",
bitrate: qualityMap[this.quality],
});
output.addVideoTrack(videoSource, { frameRate: fps });
let audioSource: AudioBufferSource | null = null;
if (this.shouldIncludeAudio && this.audioBuffer) {
let audioCodec: "aac" | "opus" =
this.format === "webm" ? "opus" : "aac";
if (audioCodec === "aac" && typeof AudioEncoder !== "undefined") {
const { supported } = await AudioEncoder.isConfigSupported({
codec: "mp4a.40.2",
sampleRate: this.audioBuffer.sampleRate,
numberOfChannels: this.audioBuffer.numberOfChannels,
bitrate: 192000,
});
if (!supported) audioCodec = "opus";
}
audioSource = new AudioBufferSource({
codec: audioCodec,
bitrate: qualityMap[this.quality],
});
output.addAudioTrack(audioSource);
}
await output.start();
if (audioSource && this.audioBuffer) {
await audioSource.add(this.audioBuffer);
audioSource.close();
}
for (let i = 0; i < frameCount; i++) {
if (this.isCancelled) {
await output.cancel();
this.emit("cancelled");
return null;
}
const time = i / fps;
await this.renderer.render({ node: rootNode, time });
await videoSource.add(time, 1 / fps);
this.emit("progress", i / frameCount);
}
if (this.isCancelled) {
await output.cancel();
this.emit("cancelled");
return null;
}
videoSource.close();
await output.finalize();
this.emit("progress", 1);
const buffer = output.target.buffer;
if (!buffer) {
this.emit("error", new Error("Failed to export video"));
return null;
}
this.emit("complete", buffer);
return buffer;
}
}
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