@mediaway/encoder

Automatic hardware video encoding to fragmented MP4 over Mediaway's C ABI. openAutoEncoder() picks a working backend for your machine (NVENC, Vulkan Video, or QuickSync on Windows), wires it to the fMP4 muxer, and returns a session you push frames into.

Windows is the verified platform. Software fallbacks and other platforms are explicit follow-up work — see the Mediaway roadmap.

Video/audio decode moved to its own peer package, @mediaway/decoder — it is not re-exported here anymore.

Capture-to-encode bridge

EncodeSession.writeFrameFromCameraCapture(capture) / .writeFrameFromDesktopCapture(capture) poll a CameraSession/ScreenSession (@mediaway/device) and push straight into the session — no intermediate VideoFrame, no CPU copy for Screen's GPU frames:

import { AutoVideoEncodeConfig, openAutoEncoder } from "@mediaway/encoder";
import { GpuDevice, openScreenCapture } from "@mediaway/device";

const gpuDevice = await GpuDevice.create();
const screen = await openScreenCapture({ timeBase: { num: 1, den: 30 }, gpuDevice });

const config = AutoVideoEncodeConfig.defaults("h264", screen.width, screen.height, screen.timeBase);
config.gpuDevice = gpuDevice; // Zero-Copy GPU input, same device as capture
config.pixelFormat = "bgra8"; // DXGI Desktop Duplication's native format
const session = await openAutoEncoder(config);

while (recording) {
  await session.writeFrameFromDesktopCapture(screen); // returns false if nothing was ready yet
}
const mp4 = await session.finish();

Install

npm install @mediaway/encoder

Example

import { openAutoEncoder, AutoVideoEncodeConfig, EncoderUnavailableError, type VideoFrame } from "@mediaway/encoder";
import type { Rational } from "@mediaway/container";

const TIME_BASE: Rational = { num: 1, den: 30 };

const config = AutoVideoEncodeConfig.defaults("h264", 640, 480, TIME_BASE);
config.bitrateBps = 1_500_000; // override the backend default

let session;
try {
  session = await openAutoEncoder(config);
} catch (err) {
  if (err instanceof EncoderUnavailableError) {
    console.log("no hardware encoder available on this machine");
    process.exit(1);
  }
  throw err;
}

const greyFrame = Buffer.alloc(640 * 480 * 1.5); // NV12 (or i420/bgra8/rgba8)
for (let i = 0; i < 90; i++) {
  greyFrame.fill(i % 255);
  await session.writeFrame({
    data: greyFrame, // safe to reuse: the wrapper copies per writeFrame call
    width: 640,
    height: 480,
    pixelFormat: "nv12",
    pts: i,          // ticks of the config timeBase
  } satisfies VideoFrame);
}

const mp4 = await session.finish(); // terminal: complete fMP4 bytes
// -> write `mp4` to a file / stream

API

| Member | Notes | | --- | --- | | AutoVideoEncodeConfig.defaults(codec, width, height, timeBase) | sensible defaults for the resolution; codec is "h264" \| "hevc" \| "av1" \| "vp9" | | AutoVideoEncodeConfig.gpuDevice | a GpuDevice (@mediaway/device) for Zero-Copy GPU input; pair with pixelFormat: "bgra8" for Screen | | openAutoEncoder(config) | resolves a hardware backend or throws EncoderUnavailableError | | EncodeSession.writeFrame(frame) | async; the frame is copied — reuse the buffer | | EncodeSession.writeFrameFromCameraCapture(capture) / writeFrameFromDesktopCapture(capture) | async; polls+pushes a capture session directly, false if nothing was ready | | EncodeSession.finish() | terminal; returns the complete fMP4 Buffer |

License

MIT OR Apache-2.0. Part of the Mediaway project — pre-1.0, APIs may change.