Recording Videos

Video or it Didn't Happen 🤨

Recording videos is the most fundamental feature of VideoKit (if it wasn't already obvious from the name). In this guide, we will explore how to record videos with and without code.

Using the Recorder Component

The first step is to create a VideoKitRecorder component:

Starting a Recording

Next, we need to invoke VideoKitRecorder.StartRecording when we want to begin a recording session. For this, we can use a UI button:

Stopping a Recording

Before we take our setup for a spin, we should add another button to stop the recording. We will add a UI button to call VideoKitRecorder.StopRecording:

Try it Out

Enter play mode, click the 'Start Recording' button, wait a few seconds, then click the 'Stop Recording' button. Navigate to your project directory and there should be a new directory called VideoKit, and within it, you should find a video of your empty scene!

Using the VideoKit API

Video recording is exposed with the MediaRecorder class.

Creating a Recorder

First, create a recorder specifying the desired format and accompanying settings:

// Create a recorder
var recorder = await MediaRecorder.Create(
    format: MediaRecorder.Format.MP4,
    width: 1280,
    height: 720,
    frameRate: 30
);

Appending Sample Buffers

The MediaRecorder is designed with a push architecture, where pixel buffers and audio buffers must explicitly be sent to the recorder using the MediaRecorder::Append method. But to simplify this process, VideoKit provides Sources which handle pulling pixel buffers and audio buffers from the screen, one or more game cameras, audio listeners, and other sources. Let's use a CameraSource to record video from the game camera:

// Create a clock to generate recording timestamps
var clock = new RealtimeClock();
// Create a camera source
var cameraSource = new CameraSource(
    recorder,     // the recorder accepts and records pixel buffers from the source
    clock,        // the clock is used to generate recording timestamps
    Camera.main   // the camera source captures pixel buffers from one or more game cameras
);

On the other hand, you can append raw pixel buffers to the recorder on-demand:

// Create a pixel buffer
Texture2D image = ...;
using var pixelBuffer = new PixelBuffer(
    image,            // texture to get pixel data from
    clock.timestamp   // pixel buffer timestamp to use for recording
);
// Append
recorder.Append(pixelBuffer);

The process is similar for appending audio buffers:

// Create an audio buffer
float[] audioData = ...;
using var audioBuffer = new AudioBuffer(
    44_100,
    2,
    audioData,
    clock.timestamp
);
// Append
recorder.Append(audioBuffer);

Finishing the Recording

To finish a recording session, stop appending sample buffers then finish writing:

// Dispose any media sources
cameraSource.Dispose();
// Finish writing
MediaAsset asset = await recorder.FinishWriting();

The recorder returns a MediaAsset which refers to a media file.

Next Steps

Now that you are familiar with the basics of video recording, continue with the following:

• Working with media assets.
• VideoKitRecorder component.
• MediaRecorder class.