export class JpegFrameExtractor {
private buffer = Buffer.alloc(0);
/**
* Feed bytes and return any complete JPEG frames found.
* JPEG frames are delimited by SOI (FFD8) and EOI (FFD9).
*/
push(chunk: Buffer): Buffer[] {
this.buffer = Buffer.concat([this.buffer, chunk]);
const frames: Buffer[] = [];
while (true) {
const soi = this.buffer.indexOf(Buffer.from([0xff, 0xd8]));
if (soi < 0) {
// Keep buffer bounded
if (this.buffer.length > 10_000_000) this.buffer = Buffer.alloc(0);
break;
}
const eoi = this.buffer.indexOf(Buffer.from([0xff, 0xd9]), soi + 2);
if (eoi < 0) {
// keep from SOI onwards
if (soi > 0) this.buffer = this.buffer.slice(soi);
break;
}
const end = eoi + 2;
const frame = this.buffer.slice(soi, end);
frames.push(frame);
this.buffer = this.buffer.slice(end);
}
return frames;
}
}
