Add @mediabunny/dts extension package

packages/dts/src/bridge.c

@@ -0,0 +1,321 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+#include <emscripten.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include "libavcodec/avcodec.h"
+#include "libavutil/opt.h"
+#include "libavutil/channel_layout.h"
+
+typedef struct {
+	AVCodecContext *codec_ctx;
+	AVPacket *packet;
+	AVFrame *frame;
+} DecoderContext;
+
+EMSCRIPTEN_KEEPALIVE
+DecoderContext *init_decoder() {
+	const AVCodec *codec = avcodec_find_decoder(AV_CODEC_ID_DTS);
+	if (!codec) return NULL;
+
+	AVCodecContext *codec_ctx = avcodec_alloc_context3(codec);
+	if (!codec_ctx) return NULL;
+
+	if (avcodec_open2(codec_ctx, codec, NULL) < 0) {
+		avcodec_free_context(&codec_ctx);
+		return NULL;
+	}
+
+	AVPacket *packet = av_packet_alloc();
+	if (!packet) {
+		avcodec_free_context(&codec_ctx);
+		return NULL;
+	}
+
+	AVFrame *frame = av_frame_alloc();
+	if (!frame) {
+		av_packet_free(&packet);
+		avcodec_free_context(&codec_ctx);
+		return NULL;
+	}
+
+	DecoderContext *ctx = malloc(sizeof(DecoderContext));
+	if (!ctx) {
+		av_frame_free(&frame);
+		av_packet_free(&packet);
+		avcodec_free_context(&codec_ctx);
+		return NULL;
+	}
+
+	ctx->codec_ctx = codec_ctx;
+	ctx->packet = packet;
+	ctx->frame = frame;
+
+	return ctx;
+}
+
+EMSCRIPTEN_KEEPALIVE
+uint8_t *configure_decode_packet(DecoderContext *ctx, int size) {
+	if (av_new_packet(ctx->packet, size) < 0) {
+		return NULL;
+	}
+
+	return ctx->packet->data;
+}
+
+EMSCRIPTEN_KEEPALIVE
+int decode_packet(DecoderContext *ctx, int64_t pts) {
+	ctx->packet->pts = pts;
+	int ret = avcodec_send_packet(ctx->codec_ctx, ctx->packet);
+	av_packet_unref(ctx->packet);
+	if (ret < 0) return ret;
+
+	ret = avcodec_receive_frame(ctx->codec_ctx, ctx->frame);
+	if (ret < 0) return ret;
+
+	return 0;
+}
+
+EMSCRIPTEN_KEEPALIVE
+int get_decoded_format(DecoderContext *ctx) {
+	return ctx->frame->format;
+}
+
+EMSCRIPTEN_KEEPALIVE
+uint8_t *get_decoded_plane_ptr(DecoderContext *ctx, int plane) {
+	return ctx->frame->data[plane];
+}
+
+EMSCRIPTEN_KEEPALIVE
+int get_decoded_channels(DecoderContext *ctx) {
+	return ctx->frame->ch_layout.nb_channels;
+}
+
+EMSCRIPTEN_KEEPALIVE
+int get_decoded_sample_rate(DecoderContext *ctx) {
+	return ctx->frame->sample_rate;
+}
+
+EMSCRIPTEN_KEEPALIVE
+int get_decoded_sample_count(DecoderContext *ctx) {
+	return ctx->frame->nb_samples;
+}
+
+EMSCRIPTEN_KEEPALIVE
+int64_t get_decoded_pts(DecoderContext *ctx) {
+	return ctx->frame->pts;
+}
+
+EMSCRIPTEN_KEEPALIVE
+void flush_decoder(DecoderContext *ctx) {
+	avcodec_send_packet(ctx->codec_ctx, NULL);
+	while (avcodec_receive_frame(ctx->codec_ctx, ctx->frame) == 0) {}
+	avcodec_flush_buffers(ctx->codec_ctx);
+}
+
+EMSCRIPTEN_KEEPALIVE
+void close_decoder(DecoderContext *ctx) {
+	av_frame_free(&ctx->frame);
+	av_packet_free(&ctx->packet);
+	avcodec_free_context(&ctx->codec_ctx);
+	free(ctx);
+}
+
+typedef struct {
+	AVCodecContext *codec_ctx;
+	AVPacket *packet;
+	AVFrame *frame;
+	float *input_buffer;
+	int input_buffer_size;
+	int64_t encoded_pts;
+	int encoded_duration;
+} EncoderContext;
+
+/**
+ * DTS insists on the side-based surround layouts and rejects the back-based ones that av_channel_layout_default hands
+ * out for 4, 5 and 6 channels.
+ */
+static int set_dts_channel_layout(AVChannelLayout *layout, int channels) {
+	switch (channels) {
+		case 1: {
+			AVChannelLayout mono = AV_CHANNEL_LAYOUT_MONO;
+			return av_channel_layout_copy(layout, &mono);
+		}
+		case 2: {
+			AVChannelLayout stereo = AV_CHANNEL_LAYOUT_STEREO;
+			return av_channel_layout_copy(layout, &stereo);
+		}
+		case 4: {
+			AVChannelLayout quad_side = AV_CHANNEL_LAYOUT_2_2;
+			return av_channel_layout_copy(layout, &quad_side);
+		}
+		case 5: {
+			AVChannelLayout five_zero = AV_CHANNEL_LAYOUT_5POINT0;
+			return av_channel_layout_copy(layout, &five_zero);
+		}
+		case 6: {
+			AVChannelLayout five_one = AV_CHANNEL_LAYOUT_5POINT1;
+			return av_channel_layout_copy(layout, &five_one);
+		}
+		default:
+			return -1;
+	}
+}
+
+EMSCRIPTEN_KEEPALIVE
+EncoderContext *init_encoder(int channels, int sample_rate, int bitrate) {
+	const AVCodec *codec = avcodec_find_encoder(AV_CODEC_ID_DTS);
+	if (!codec) return NULL;
+
+	AVCodecContext *codec_ctx = avcodec_alloc_context3(codec);
+	if (!codec_ctx) return NULL;
+
+	codec_ctx->sample_fmt = AV_SAMPLE_FMT_S32;
+	codec_ctx->sample_rate = sample_rate;
+	codec_ctx->bit_rate = bitrate;
+	codec_ctx->time_base = (AVRational){1, sample_rate};
+
+	// FFmpeg marks its DTS encoder experimental, so it refuses to open at the default compliance level
+	codec_ctx->strict_std_compliance = FF_COMPLIANCE_EXPERIMENTAL;
+
+	if (set_dts_channel_layout(&codec_ctx->ch_layout, channels) < 0) {
+		avcodec_free_context(&codec_ctx);
+		return NULL;
+	}
+
+	if (avcodec_open2(codec_ctx, codec, NULL) < 0) {
+		avcodec_free_context(&codec_ctx);
+		return NULL;
+	}
+
+	AVPacket *packet = av_packet_alloc();
+	if (!packet) {
+		avcodec_free_context(&codec_ctx);
+		return NULL;
+	}
+
+	AVFrame *frame = av_frame_alloc();
+	if (!frame) {
+		av_packet_free(&packet);
+		avcodec_free_context(&codec_ctx);
+		return NULL;
+	}
+
+	// The frame has a fixed format, so let's create it now:
+	frame->format = AV_SAMPLE_FMT_S32;
+	frame->sample_rate = sample_rate;
+	frame->nb_samples = codec_ctx->frame_size;
+	av_channel_layout_copy(&frame->ch_layout, &codec_ctx->ch_layout);
+
+	if (av_frame_get_buffer(frame, 0) < 0) {
+		av_frame_free(&frame);
+		av_packet_free(&packet);
+		avcodec_free_context(&codec_ctx);
+		return NULL;
+	}
+
+	EncoderContext *ctx = malloc(sizeof(EncoderContext));
+	if (!ctx) {
+		av_frame_free(&frame);
+		av_packet_free(&packet);
+		avcodec_free_context(&codec_ctx);
+		return NULL;
+	}
+
+	ctx->codec_ctx = codec_ctx;
+	ctx->packet = packet;
+	ctx->frame = frame;
+	ctx->input_buffer = NULL;
+	ctx->input_buffer_size = 0;
+	ctx->encoded_pts = 0;
+	ctx->encoded_duration = 0;
+
+	return ctx;
+}
+
+EMSCRIPTEN_KEEPALIVE
+int get_encoder_frame_size(EncoderContext *ctx) {
+	return ctx->codec_ctx->frame_size;
+}
+
+EMSCRIPTEN_KEEPALIVE
+float *get_encode_input_ptr(EncoderContext *ctx, int size) {
+	if (ctx->input_buffer_size < size) {
+		free(ctx->input_buffer);
+		ctx->input_buffer = malloc(size);
+		if (!ctx->input_buffer) {
+			ctx->input_buffer_size = 0;
+			return NULL;
+		}
+		ctx->input_buffer_size = size;
+	}
+	return ctx->input_buffer;
+}
+
+EMSCRIPTEN_KEEPALIVE
+int encode_frame(EncoderContext *ctx, int64_t pts) {
+	int channels = ctx->codec_ctx->ch_layout.nb_channels;
+	int frame_size = ctx->frame->nb_samples;
+
+	ctx->frame->pts = pts;
+
+	// DTS encodes from s32, which is a packed format, so the samples stay interleaved and all land in data[0]
+	float *input = ctx->input_buffer;
+	int32_t *output = (int32_t *)ctx->frame->data[0];
+	for (int i = 0; i < frame_size * channels; i++) {
+		float sample = input[i];
+		if (sample > 1.0f) sample = 1.0f;
+		if (sample < -1.0f) sample = -1.0f;
+		output[i] = (int32_t)(sample * 2147483647.0f);
+	}
+
+	int ret = avcodec_send_frame(ctx->codec_ctx, ctx->frame);
+	if (ret < 0) return ret;
+
+	ret = avcodec_receive_packet(ctx->codec_ctx, ctx->packet);
+	if (ret < 0) return ret;
+
+	ctx->encoded_pts = ctx->packet->pts;
+	ctx->encoded_duration = ctx->packet->duration;
+
+	return ctx->packet->size;
+}
+
+EMSCRIPTEN_KEEPALIVE
+void flush_encoder(EncoderContext *ctx) {
+	avcodec_send_frame(ctx->codec_ctx, NULL);
+	while (avcodec_receive_packet(ctx->codec_ctx, ctx->packet) == 0) {
+		av_packet_unref(ctx->packet);
+	}
+}
+
+EMSCRIPTEN_KEEPALIVE
+uint8_t *get_encoded_data(EncoderContext *ctx) {
+	return ctx->packet->data;
+}
+
+EMSCRIPTEN_KEEPALIVE
+int64_t get_encoded_pts(EncoderContext *ctx) {
+	return ctx->encoded_pts;
+}
+
+EMSCRIPTEN_KEEPALIVE
+int get_encoded_duration(EncoderContext *ctx) {
+	return ctx->encoded_duration;
+}
+
+EMSCRIPTEN_KEEPALIVE
+void close_encoder(EncoderContext *ctx) {
+	free(ctx->input_buffer);
+	av_frame_free(&ctx->frame);
+	av_packet_free(&ctx->packet);
+	avcodec_free_context(&ctx->codec_ctx);
+	free(ctx);
+}

packages/dts/src/codec.worker.ts

@@ -0,0 +1,306 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import createModule from '../build/dts';
+import type { WorkerCommand, WorkerResponse, WorkerResponseData } from './shared';
+
+type ExtendedEmscriptenModule = EmscriptenModule & {
+	cwrap: typeof cwrap;
+};
+
+let module: ExtendedEmscriptenModule;
+let modulePromise: Promise<ExtendedEmscriptenModule> | null = null;
+
+let initDecoderFn: () => number;
+let configureDecodePacket: (ctx: number, size: number) => number;
+let decodePacket: (ctx: number, pts: bigint) => number;
+let getDecodedFormat: (ctx: number) => number;
+let getDecodedPlanePtr: (ctx: number, plane: number) => number;
+let getDecodedChannels: (ctx: number) => number;
+let getDecodedSampleRate: (ctx: number) => number;
+let getDecodedSampleCount: (ctx: number) => number;
+let getDecodedPts: (ctx: number) => bigint;
+let flushDecoderFn: (ctx: number) => void;
+let closeDecoderFn: (ctx: number) => void;
+
+let initEncoderFn: (channels: number, sampleRate: number, bitrate: number) => number;
+let getEncoderFrameSize: (ctx: number) => number;
+let getEncodeInputPtr: (ctx: number, size: number) => number;
+let encodeFrameFn: (ctx: number, pts: bigint) => number;
+let flushEncoderFn: (ctx: number) => void;
+let getEncodedData: (ctx: number) => number;
+let getEncodedPts: (ctx: number) => bigint;
+let getEncodedDuration: (ctx: number) => number;
+let closeEncoderFn: (ctx: number) => void;
+
+const ensureModule = async () => {
+	if (!module) {
+		if (modulePromise) {
+			// If we don't do this we can have a race condition
+			return modulePromise;
+		}
+
+		modulePromise = createModule() as Promise<ExtendedEmscriptenModule>;
+		module = await modulePromise;
+		modulePromise = null;
+
+		initDecoderFn = module.cwrap('init_decoder', 'number', []);
+		configureDecodePacket = module.cwrap('configure_decode_packet', 'number', ['number', 'number']);
+		decodePacket = module.cwrap('decode_packet', 'number', ['number', 'number']) as unknown as typeof decodePacket;
+		getDecodedFormat = module.cwrap('get_decoded_format', 'number', ['number']);
+		getDecodedPlanePtr = module.cwrap('get_decoded_plane_ptr', 'number', ['number', 'number']);
+		getDecodedChannels = module.cwrap('get_decoded_channels', 'number', ['number']);
+		getDecodedSampleRate = module.cwrap('get_decoded_sample_rate', 'number', ['number']);
+		getDecodedSampleCount = module.cwrap('get_decoded_sample_count', 'number', ['number']);
+		getDecodedPts = module.cwrap('get_decoded_pts', 'number', ['number']) as unknown as typeof getDecodedPts;
+		flushDecoderFn = module.cwrap('flush_decoder', null, ['number']);
+		closeDecoderFn = module.cwrap('close_decoder', null, ['number']);
+
+		initEncoderFn = module.cwrap('init_encoder', 'number', ['number', 'number', 'number']);
+		getEncoderFrameSize = module.cwrap('get_encoder_frame_size', 'number', ['number']);
+		getEncodeInputPtr = module.cwrap('get_encode_input_ptr', 'number', ['number', 'number']);
+		encodeFrameFn = module.cwrap('encode_frame', 'number', ['number', 'number']) as unknown as typeof encodeFrameFn;
+		flushEncoderFn = module.cwrap('flush_encoder', null, ['number']);
+		getEncodedData = module.cwrap('get_encoded_data', 'number', ['number']);
+		getEncodedPts = module.cwrap('get_encoded_pts', 'number', ['number']) as unknown as typeof getEncodedPts;
+		getEncodedDuration = module.cwrap('get_encoded_duration', 'number', ['number']);
+		closeEncoderFn = module.cwrap('close_encoder', null, ['number']);
+	}
+};
+
+const initDecoder = async () => {
+	await ensureModule();
+
+	const ctx = initDecoderFn();
+	if (ctx === 0) {
+		throw new Error('Failed to initialize DTS decoder.');
+	}
+
+	return { ctx, frameSize: 0 };
+};
+
+// Keys are AVSampleFormat enum values
+const AV_FORMAT_MAP: Record<number, { format: AudioSampleFormat; bytesPerSample: number; planar: boolean }> = {
+	0: { format: 'u8', bytesPerSample: 1, planar: false },
+	1: { format: 's16', bytesPerSample: 2, planar: false },
+	2: { format: 's32', bytesPerSample: 4, planar: false },
+	3: { format: 'f32', bytesPerSample: 4, planar: false },
+	5: { format: 'u8-planar', bytesPerSample: 1, planar: true },
+	6: { format: 's16-planar', bytesPerSample: 2, planar: true },
+	7: { format: 's32-planar', bytesPerSample: 4, planar: true },
+	8: { format: 'f32-planar', bytesPerSample: 4, planar: true },
+};
+
+const decode = (ctx: number, encodedData: ArrayBuffer, timestamp: number) => {
+	const bytes = new Uint8Array(encodedData);
+
+	const dataPtr = configureDecodePacket(ctx, bytes.length);
+	if (dataPtr === 0) {
+		throw new Error('Failed to configure decode packet.');
+	}
+
+	module.HEAPU8.set(bytes, dataPtr);
+
+	const ret = decodePacket(ctx, BigInt(timestamp));
+	if (ret < 0) {
+		throw new Error(`Decode failed with error code ${ret}.`);
+	}
+
+	const avFormat = getDecodedFormat(ctx);
+	const info = AV_FORMAT_MAP[avFormat];
+	if (!info) {
+		throw new Error(`Unsupported AVSampleFormat: ${avFormat}`);
+	}
+
+	const channels = getDecodedChannels(ctx);
+	const sampleRate = getDecodedSampleRate(ctx);
+	const sampleCount = getDecodedSampleCount(ctx);
+	const pts = Number(getDecodedPts(ctx));
+
+	let pcmData: ArrayBuffer;
+	if (info.planar) {
+		const planeSize = sampleCount * info.bytesPerSample;
+		const buffer = new Uint8Array(planeSize * channels);
+
+		for (let ch = 0; ch < channels; ch++) {
+			const ptr = getDecodedPlanePtr(ctx, ch);
+			buffer.set(module.HEAPU8.subarray(ptr, ptr + planeSize), ch * planeSize);
+		}
+
+		pcmData = buffer.buffer;
+	} else {
+		const totalSize = sampleCount * channels * info.bytesPerSample;
+		const ptr = getDecodedPlanePtr(ctx, 0);
+		pcmData = module.HEAPU8.slice(ptr, ptr + totalSize).buffer;
+	}
+
+	return { pcmData, format: info.format, channels, sampleRate, sampleCount, pts };
+};
+
+const initEncoder = async (
+	numberOfChannels: number,
+	sampleRate: number,
+	bitrate: number,
+) => {
+	await ensureModule();
+
+	const ctx = initEncoderFn(numberOfChannels, sampleRate, bitrate);
+	if (ctx === 0) {
+		throw new Error('Failed to initialize DTS encoder.');
+	}
+
+	return { ctx, frameSize: getEncoderFrameSize(ctx) };
+};
+
+const encode = (ctx: number, audioData: ArrayBuffer, timestamp: number) => {
+	const audioBytes = new Uint8Array(audioData);
+
+	const inputPtr = getEncodeInputPtr(ctx, audioBytes.length);
+	if (inputPtr === 0) {
+		throw new Error('Failed to allocate encoder input buffer.');
+	}
+	module.HEAPU8.set(audioBytes, inputPtr);
+
+	const bytesWritten = encodeFrameFn(ctx, BigInt(timestamp));
+	if (bytesWritten < 0) {
+		throw new Error(`Encode failed with error code ${bytesWritten}.`);
+	}
+
+	const ptr = getEncodedData(ctx);
+	const encodedData = module.HEAPU8.slice(ptr, ptr + bytesWritten).buffer;
+	const pts = Number(getEncodedPts(ctx));
+	const duration = getEncodedDuration(ctx);
+
+	return { encodedData, pts, duration };
+};
+
+const flushEncoder = (ctx: number) => {
+	flushEncoderFn(ctx);
+};
+
+const onMessage = (data: { id: number; command: WorkerCommand }) => {
+	const { id, command } = data;
+
+	const handleCommand = async (): Promise<void> => {
+		try {
+			let result: WorkerResponseData;
+			const transferables: Transferable[] = [];
+
+			switch (command.type) {
+				case 'init-decoder': {
+					const { ctx, frameSize } = await initDecoder();
+					result = { type: command.type, ctx, frameSize };
+				}; break;
+
+				case 'decode': {
+					const decoded = decode(command.data.ctx, command.data.encodedData, command.data.timestamp);
+					result = {
+						type: command.type,
+						pcmData: decoded.pcmData,
+						format: decoded.format,
+						channels: decoded.channels,
+						sampleRate: decoded.sampleRate,
+						sampleCount: decoded.sampleCount,
+						pts: decoded.pts,
+					};
+					transferables.push(decoded.pcmData);
+				}; break;
+
+				case 'flush-decoder': {
+					flushDecoderFn(command.data.ctx);
+					result = { type: command.type };
+				}; break;
+
+				case 'close-decoder': {
+					closeDecoderFn(command.data.ctx);
+					result = { type: command.type };
+				}; break;
+
+				case 'init-encoder': {
+					const { ctx, frameSize } = await initEncoder(
+						command.data.numberOfChannels,
+						command.data.sampleRate,
+						command.data.bitrate,
+					);
+					result = { type: command.type, ctx, frameSize };
+				}; break;
+
+				case 'encode': {
+					const encoded = encode(
+						command.data.ctx,
+						command.data.audioData,
+						command.data.timestamp,
+					);
+					result = {
+						type: command.type,
+						encodedData: encoded.encodedData,
+						pts: encoded.pts,
+						duration: encoded.duration,
+					};
+					transferables.push(encoded.encodedData);
+				}; break;
+
+				case 'flush-encoder': {
+					flushEncoder(command.data.ctx);
+					result = { type: command.type };
+				}; break;
+
+				case 'close-encoder': {
+					closeEncoderFn(command.data.ctx);
+					result = { type: command.type };
+				}; break;
+			}
+
+			const response: WorkerResponse = {
+				id,
+				success: true,
+				data: result,
+			};
+			sendMessage(response, transferables);
+		} catch (error: unknown) {
+			const response: WorkerResponse = {
+				id,
+				success: false,
+				error,
+			};
+			sendMessage(response);
+		}
+	};
+
+	void handleCommand();
+};
+
+const sendMessage = (data: unknown, transferables?: Transferable[]) => {
+	if (parentPort) {
+		parentPort.postMessage(data, transferables ?? []);
+	} else {
+		self.postMessage(data, { transfer: transferables ?? [] });
+	}
+};
+
+let parentPort: {
+	postMessage: (data: unknown, transferables?: Transferable[]) => void;
+	on: (event: string, listener: (data: never) => void) => void;
+} | null = null;
+
+if (typeof self === 'undefined') {
+	const workerModule = 'worker_threads';
+	// eslint-disable-next-line @stylistic/max-len
+	// eslint-disable-next-line @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-require-imports, @typescript-eslint/no-unsafe-member-access
+	parentPort = require(workerModule).parentPort;
+}
+
+if (parentPort) {
+	parentPort.on('message', onMessage);
+} else {
+	self.addEventListener('message', event => onMessage(event.data as { id: number; command: WorkerCommand }));
+}
+
+// Prevents the worker for being randomly closed by Firefox
+// https://github.com/Vanilagy/mediabunny/issues/435
+setInterval(() => {}, 1000);

packages/dts/src/decoder.ts

@@ -0,0 +1,80 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import {
+	CustomAudioDecoder,
+	AudioCodec,
+	AudioSample,
+	EncodedPacket,
+	registerDecoder,
+} from 'mediabunny';
+import { sendCommand, refWorker, unrefWorker } from './worker-client';
+
+class DtsDecoder extends CustomAudioDecoder {
+	private ctx = 0;
+
+	static override supports(codec: AudioCodec): boolean {
+		return codec === 'dts';
+	}
+
+	async init() {
+		await refWorker();
+
+		const result = await sendCommand({
+			type: 'init-decoder',
+			data: {},
+		});
+		this.ctx = result.ctx;
+	}
+
+	async decode(packet: EncodedPacket) {
+		const encodedData = packet.data.slice().buffer;
+		const timestamp = Math.round(packet.timestamp * this.config.sampleRate);
+
+		const result = await sendCommand({
+			type: 'decode',
+			data: { ctx: this.ctx, encodedData, timestamp },
+		}, [encodedData]);
+
+		const sample = new AudioSample({
+			data: result.pcmData,
+			format: result.format,
+			numberOfChannels: result.channels,
+			sampleRate: result.sampleRate,
+			timestamp: result.pts / result.sampleRate,
+		});
+		this.onSample(sample);
+	}
+
+	async flush() {
+		await sendCommand({ type: 'flush-decoder', data: { ctx: this.ctx } });
+	}
+
+	async close() {
+		void sendCommand({ type: 'close-decoder', data: { ctx: this.ctx } });
+		await unrefWorker();
+	}
+}
+
+let registered = false;
+
+/**
+ * Registers a DTS audio decoder, which Mediabunny will then use automatically when applicable. Make sure to call this
+ * function before starting any decoding task.
+ *
+ * @group \@mediabunny/dts
+ * @public
+ */
+export const registerDtsDecoder = () => {
+	if (registered) {
+		return;
+	}
+	registered = true;
+
+	registerDecoder(DtsDecoder);
+};

packages/dts/src/encoder.ts

@@ -0,0 +1,197 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import {
+	CustomAudioEncoder,
+	AudioCodec,
+	AudioSample,
+	EncodedPacket,
+	registerEncoder,
+} from 'mediabunny';
+import { sendCommand, refWorker, unrefWorker } from './worker-client';
+import { assert } from './shared';
+import { DTS_CHANNEL_COUNTS, DTS_SAMPLE_RATES, dtsBitrateFits } from '../../../shared/dts-misc';
+
+class DtsEncoder extends CustomAudioEncoder {
+	private ctx = 0;
+	private encoderFrameSize = 0;
+	private sampleRate = 0;
+	private numberOfChannels = 0;
+	private chunkMetadata: EncodedAudioChunkMetadata = {};
+
+	// Accumulate interleaved f32 samples until we have a full frame
+	private pendingBuffer = new Float32Array(2 ** 16);
+	private pendingFrames = 0;
+	private nextSampleTimestampInSamples: number | null = null;
+	private nextPacketTimestampInSamples: number | null = null;
+
+	static override supports(codec: AudioCodec, config: AudioEncoderConfig): boolean {
+		return codec === 'dts'
+			&& DTS_CHANNEL_COUNTS.includes(config.numberOfChannels)
+			&& DTS_SAMPLE_RATES.includes(config.sampleRate)
+			&& config.bitrate !== undefined
+			&& dtsBitrateFits(config.bitrate, config.sampleRate, config.numberOfChannels);
+	}
+
+	async init() {
+		await refWorker();
+
+		assert(this.config.bitrate !== undefined);
+		this.sampleRate = this.config.sampleRate;
+		this.numberOfChannels = this.config.numberOfChannels;
+
+		const result = await sendCommand({
+			type: 'init-encoder',
+			data: {
+				numberOfChannels: this.config.numberOfChannels,
+				sampleRate: this.config.sampleRate,
+				bitrate: this.config.bitrate,
+			},
+		});
+
+		this.ctx = result.ctx;
+		this.encoderFrameSize = result.frameSize;
+
+		this.resetInternalState();
+	}
+
+	private resetInternalState() {
+		this.pendingFrames = 0;
+		this.nextSampleTimestampInSamples = null;
+		this.nextPacketTimestampInSamples = null;
+
+		this.chunkMetadata = {
+			decoderConfig: {
+				codec: 'dtsc',
+				numberOfChannels: this.config.numberOfChannels,
+				sampleRate: this.config.sampleRate,
+			},
+		};
+	}
+
+	async encode(audioSample: AudioSample) {
+		if (this.nextSampleTimestampInSamples === null) {
+			this.nextSampleTimestampInSamples = Math.round(audioSample.timestamp * this.sampleRate);
+			this.nextPacketTimestampInSamples = this.nextSampleTimestampInSamples;
+		}
+
+		const channels = this.numberOfChannels;
+		const incomingFrames = audioSample.numberOfFrames;
+
+		// Extract interleaved f32 data
+		const totalBytes = audioSample.allocationSize({ format: 'f32', planeIndex: 0 });
+		const audioBytes = new Uint8Array(totalBytes);
+		audioSample.copyTo(audioBytes, { format: 'f32', planeIndex: 0 });
+		const incomingData = new Float32Array(audioBytes.buffer);
+
+		const requiredSamples = (this.pendingFrames + incomingFrames) * channels;
+		if (requiredSamples > this.pendingBuffer.length) {
+			let newSize = this.pendingBuffer.length;
+			while (newSize < requiredSamples) {
+				newSize *= 2;
+			}
+			const newBuffer = new Float32Array(newSize);
+			newBuffer.set(this.pendingBuffer.subarray(0, this.pendingFrames * channels));
+			this.pendingBuffer = newBuffer;
+		}
+		this.pendingBuffer.set(incomingData, this.pendingFrames * channels);
+		this.pendingFrames += incomingFrames;
+
+		while (this.pendingFrames >= this.encoderFrameSize) {
+			await this.encodeOneFrame();
+		}
+	}
+
+	async flush() {
+		// Pad remaining samples with silence to fill a full frame
+		if (this.pendingFrames > 0) {
+			const channels = this.numberOfChannels;
+			const frameSize = this.encoderFrameSize;
+			const usedSamples = this.pendingFrames * channels;
+			const frameSamples = frameSize * channels;
+
+			this.pendingBuffer.fill(0, usedSamples, frameSamples);
+			this.pendingFrames = frameSize;
+
+			await this.encodeOneFrame();
+		}
+
+		await sendCommand({ type: 'flush-encoder', data: { ctx: this.ctx } });
+
+		this.resetInternalState();
+	}
+
+	close() {
+		void sendCommand({ type: 'close-encoder', data: { ctx: this.ctx } });
+		void unrefWorker();
+	}
+
+	private async encodeOneFrame() {
+		assert(this.nextSampleTimestampInSamples !== null);
+		assert(this.nextPacketTimestampInSamples !== null);
+
+		const channels = this.numberOfChannels;
+		const frameSize = this.encoderFrameSize;
+		const frameSamples = frameSize * channels;
+
+		const frameData = this.pendingBuffer.slice(0, frameSamples);
+
+		// Shift remaining using copyWithin
+		this.pendingFrames -= frameSize;
+		if (this.pendingFrames > 0) {
+			this.pendingBuffer.copyWithin(0, frameSamples, frameSamples + this.pendingFrames * channels);
+		}
+
+		const audioData = frameData.buffer;
+		const result = await sendCommand({
+			type: 'encode',
+			data: {
+				ctx: this.ctx,
+				audioData,
+				timestamp: this.nextSampleTimestampInSamples,
+			},
+		}, [audioData]);
+
+		this.nextSampleTimestampInSamples += frameSize;
+
+		// We always get exactly one packet because we encode the correct frame size
+		const packet = new EncodedPacket(
+			new Uint8Array(result.encodedData),
+			'key',
+			this.nextPacketTimestampInSamples / this.sampleRate,
+			result.duration / this.sampleRate,
+		);
+
+		this.nextPacketTimestampInSamples += result.duration;
+
+		this.onPacket(
+			packet,
+			this.chunkMetadata,
+		);
+
+		this.chunkMetadata = {};
+	}
+}
+
+let registered = false;
+
+/**
+ * Registers a DTS audio encoder, which Mediabunny will then use automatically when applicable. Make sure to call this
+ * function before starting any encoding task.
+ *
+ * @group \@mediabunny/dts
+ * @public
+ */
+export const registerDtsEncoder = () => {
+	if (registered) {
+		return;
+	}
+	registered = true;
+
+	registerEncoder(DtsEncoder);
+};

packages/dts/src/index.ts

@@ -0,0 +1,23 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import { Logging } from 'mediabunny';
+
+const DTS_LOADED_SYMBOL = Symbol.for('@mediabunny/dts loaded');
+if ((globalThis as Record<symbol, unknown>)[DTS_LOADED_SYMBOL]) {
+	Logging._error(
+		'[WARNING]\n@mediabunny/dts was loaded twice.'
+		+ ' This will likely cause the encoder/decoder not to work correctly.'
+		+ ' Check if multiple dependencies are importing different versions of @mediabunny/dts,'
+		+ ' or if something is being bundled incorrectly.',
+	);
+}
+(globalThis as Record<symbol, unknown>)[DTS_LOADED_SYMBOL] = true;
+
+export { registerDtsDecoder } from './decoder';
+export { registerDtsEncoder } from './encoder';

packages/dts/src/shared.ts

@@ -0,0 +1,100 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+export type WorkerCommand = {
+	type: 'init-decoder';
+	data: Record<string, never>;
+} | {
+	type: 'decode';
+	data: {
+		ctx: number;
+		encodedData: ArrayBuffer;
+		timestamp: number;
+	};
+} | {
+	type: 'flush-decoder';
+	data: {
+		ctx: number;
+	};
+} | {
+	type: 'close-decoder';
+	data: {
+		ctx: number;
+	};
+} | {
+	type: 'init-encoder';
+	data: {
+		numberOfChannels: number;
+		sampleRate: number;
+		bitrate: number;
+	};
+} | {
+	type: 'encode';
+	data: {
+		ctx: number;
+		audioData: ArrayBuffer;
+		timestamp: number;
+	};
+} | {
+	type: 'flush-encoder';
+	data: {
+		ctx: number;
+	};
+} | {
+	type: 'close-encoder';
+	data: {
+		ctx: number;
+	};
+};
+
+export type WorkerResponseData = {
+	type: 'init-decoder';
+	ctx: number;
+	frameSize: number;
+} | {
+	type: 'decode';
+	pcmData: ArrayBuffer;
+	format: AudioSampleFormat;
+	channels: number;
+	sampleRate: number;
+	sampleCount: number;
+	pts: number;
+} | {
+	type: 'flush-decoder';
+} | {
+	type: 'close-decoder';
+} | {
+	type: 'init-encoder';
+	ctx: number;
+	frameSize: number;
+} | {
+	type: 'encode';
+	encodedData: ArrayBuffer;
+	pts: number;
+	duration: number;
+} | {
+	type: 'flush-encoder';
+} | {
+	type: 'close-encoder';
+};
+
+export type WorkerResponse = {
+	id: number;
+} & ({
+	success: true;
+	data: WorkerResponseData;
+} | {
+	success: false;
+	error: unknown;
+});
+
+export function assert(x: unknown): asserts x {
+	if (!x) {
+		throw new Error('Assertion failed.');
+	}
+}

packages/dts/src/worker-client.ts

@@ -0,0 +1,109 @@
+/*!
+ * Copyright (c) 2026-present, Vanilagy and contributors
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+import { assert, type WorkerCommand, type WorkerResponse, type WorkerResponseData } from './shared';
+// @ts-expect-error An esbuild plugin handles this, TypeScript doesn't need to understand
+import createWorker from './codec.worker';
+
+type ExtendedWorker = Worker & {
+	ref?: () => void;
+	unref?: () => void;
+};
+
+let workerPromise: Promise<ExtendedWorker> | null;
+let nextMessageId = 0;
+const pendingMessages = new Map<number, {
+	resolve: (value: WorkerResponseData) => void;
+	reject: (reason?: unknown) => void;
+}>();
+
+let refCount = 0;
+let keepAliveInterval: ReturnType<typeof setInterval> | null = null;
+
+export const refWorker = async () => {
+	refCount++;
+	if (refCount === 1) {
+		keepAliveInterval = setInterval(() => {}, 2 ** 31 - 1);
+		const worker = await ensureWorker();
+		worker.ref?.();
+	}
+};
+
+export const unrefWorker = async () => {
+	refCount--;
+	if (refCount === 0) {
+		if (keepAliveInterval !== null) {
+			clearInterval(keepAliveInterval);
+			keepAliveInterval = null;
+		}
+
+		const worker = await workerPromise;
+		if (worker) {
+			if (worker.unref) {
+				worker.unref(); // If we don't do this, then the Node process never terminates by itself
+				// Keep the worker around tho
+			} else if (typeof window === 'undefined') {
+				// Non-browser environment without unref - terminate instead
+				worker.terminate();
+				workerPromise = null;
+			}
+		}
+	}
+};
+
+export const sendCommand = async <T extends string>(
+	command: WorkerCommand & { type: T },
+	transferables?: Transferable[],
+) => {
+	const worker = await ensureWorker();
+
+	return new Promise<WorkerResponseData & { type: T }>((resolve, reject) => {
+		const id = nextMessageId++;
+		pendingMessages.set(id, {
+			resolve: resolve as (value: WorkerResponseData) => void,
+			reject,
+		});
+
+		if (transferables) {
+			worker.postMessage({ id, command }, transferables);
+		} else {
+			worker.postMessage({ id, command });
+		}
+	});
+};
+
+const ensureWorker = () => {
+	return workerPromise ??= (async () => {
+		// eslint-disable-next-line @typescript-eslint/no-unsafe-call
+		const worker = (await createWorker()) as ExtendedWorker;
+		worker.unref?.(); // Start unreffed
+
+		const onMessage = (data: WorkerResponse) => {
+			const pending = pendingMessages.get(data.id);
+			assert(pending !== undefined);
+
+			pendingMessages.delete(data.id);
+			if (data.success) {
+				pending.resolve(data.data);
+			} else {
+				pending.reject(data.error);
+			}
+		};
+
+		if (worker.addEventListener) {
+			worker.addEventListener('message', event => onMessage(event.data as WorkerResponse));
+		} else {
+			const nodeWorker = worker as unknown as {
+				on: (event: string, listener: (data: never) => void) => void;
+			};
+			nodeWorker.on('message', onMessage);
+		}
+
+		return worker;
+	})();
+};