Test of transcoding with beamcoder

transcode-test.js

// Revised 2/26/20 with a video filter to try using setpts - didn't help...
// Ticket ongoing at https://github.com/Streampunk/beamcoder/issues/36
const beamcoder = require('beamcoder');
async function main() {
	// Get this file from http://dl5.webmfiles.org/big-buck-bunny_trailer.webm
	let demuxer = await beamcoder.demuxer('file:./big-buck-bunny_trailer.webm');
	let decoder = beamcoder.decoder({ demuxer, stream_index: 0 });

	const inVideoStream = demuxer.streams[0];
	// console.log(JSON.parse(JSON.stringify(inVideoStream)));

	let encParams = {
		name: 'libx264',
		width: inVideoStream.codecpar.width,
		height: inVideoStream.codecpar.height,
		bit_rate: 2000000,
		time_base: [1, 25],
		framerate: [25, 1],
		gop_size: 10,
		max_b_frames: 1,
		pix_fmt: inVideoStream.codecpar.format,
		priv_data: { preset: 'slow' }
	};
	
	let encoder = await beamcoder.encoder(encParams);
	// console.log('Encoder', encoder);
	
	const mux = beamcoder.muxer({ format_name: 'mp4' });
	let vstr = mux.newStream({
		name: 'h264',
		time_base: [1, 90000],
		interleaved: true }); // Set to false for manual interleaving, true for automatic
	Object.assign(vstr.codecpar, {
		width: inVideoStream.codecpar.width,
		height: inVideoStream.codecpar.height,
		format: inVideoStream.codecpar.format
	});
	// console.log(vstr);
	await mux.openIO({
		url: 'file:./reencode.mp4'
	});
	await mux.writeHeader();

	const writePackets = async packets => {
		for (const pkt of packets.packets) {
			pkt.duration = 1;
			pkt.stream_index = vstr.index;
			pkt.pts = pkt.pts * 90000/25;
			pkt.dts = pkt.dts * 90000/25;
			await mux.writeFrame(pkt);
		}
	}

	// Filter example derived from https://github.com/Streampunk/beamcoder#filterer
	const filterDef = {
		filterType: 'video',
		inputParams: [{
			width: inVideoStream.codecpar.width,
			height: inVideoStream.codecpar.height,
			pixelFormat: inVideoStream.codecpar.format,
			timeBase: inVideoStream.time_base,
			pixelAspect: inVideoStream.sample_aspect_ratio,
		}],
		outputParams: [{
			pixelFormat: inVideoStream.codecpar.format,
			// FIXME should this be the timeBase of the video stream or the encoder ?
			timeBase:    [1, 9000],
		}],
		filterSpec: 
			// This was just used to make sure filtering was working
			//'scale=' + inVideoStream.codecpar.width + ':' + inVideoStream.codecpar.height + ','
			
			// All "setpts" examples taken from https://ffmpeg.org/ffmpeg-filters.html#setpts_002c-asetpts
			// NOTE: Elsewhere on that page (ffmpeg-filters.html) anytime that 'setpts'
			// is used with other filters, it always is "setpts=PTS-STARTPTS"
			// However, this does NOTHING to fix the timing problem - time is still way too slow
			'setpts=PTS-STARTPTS'

			// XXX BAD: Produces visually corrupted video output
			// ',setpts=N/SR/TB'

			// XXX BAD: "Works" in that time is real time, but when transcoding,
			// it will stutter when encoder uses time if not encoding in realtime
			// ',setpts=(RTCTIME - RTCSTART) / (TB * 1000000)'

			// XXX BAD: Does not work, produces same result as bug
			// ',setpts=N/(25*TB)',

			// XXX BAD: Does not work, produces same result as bug
			// ',setpts=1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'

			// XXX BAD: Does not work, produces same result as bug			
			// ',setpts=PTS-STARTPTS'
	};

	const filter = await beamcoder.filterer(filterDef);

	let packet = true;
	let counter = 0, pts = 0;
	while (packet != null && counter ++ < 1000) {
		packet = await demuxer.read();
		const dec_result = await decoder.decode(packet);

		if(dec_result.frames.length > 0) {

			// FIXME(1): This works but is messy - and will break when mixing
			// multiple sources and audio will not be in sync
			// dec_result.frames.forEach(frame => frame.pts = pts ++);
			// let packets = await encoder.encode(dec_result.frames);
			
			// FIXME(2): This DOES NOT WORK - video still plays very in wrong time
			const output = await filter.filter(dec_result.frames);
			let packets = await encoder.encode(output[0].frames);

			if ( counter % 10 === 0) console.log('Encoding frame', counter);
			await writePackets(packets);
		}
	}

	let p2 = await encoder.flush();
	console.log('Flushing', p2.packets.length, 'frames.');
	await writePackets(p2);

	await mux.writeTrailer();

	console.log("Done");
}

main().catch(e => console.warn("Caught:", e));