GHZSDKXR/Runtime/Shared/Scripts/Recorders

NatCorder API

NatCorder is a lightweight, easy-to-use, native video recording API for iOS, Android, macOS, and Windows. NatCorder comes with a rich featureset including:

• Record any texture, anything that can be rendered into a texture, or any pixel data.
• Record to MP4 videos and animated GIF images.
• Control recording quality and file size with bitrate and keyframe interval.
• Record at any resolution. You get to specify what resolution recording you want.
• Get path to recorded video in device storage.
• Record game audio with video.
• Support for recording HEVC videos.

Fundamentals of Recording

NatCorder provides a simple recording API with instances of the IMediaRecorder interface. NatCorder works by encoding video and audio frames on demand. To start recording, simply create a recorder corresponding to the media type you want to record:

var gifRecorder = new GIFRecorder(...);
var mp4Recorder = new MP4Recorder(...);
var hevcRecorder = new HEVCRecorder(...);

Once you create a recorder, you then commit frames to it. You can commit video and audio frames to these recorders. These committed frames are then encoded into a media file. When committing frames, you must provide the frame data with a corresponding timestamp. The spacing between timestamps determine the final frame rate of the recording.

Committing Video Frames

NatCorder records video using pixel buffers. The pixel buffers must be 32-bit per pixel, RGBA encoding (TextureFormat.RGBA32). The managed type of the pixel buffer is entirely flexible. As a result, you can commit a Color32[], a byte[], an int[], or any struct array that can be interpreted as an RGBA32 pixel buffer.

When committing a pixel buffer for encoding, you will need to provide a corresponding timestamp. For this purpose, you can use implementations of the IClock interface. Here is an example illustrating recording a WebCamTexture:

async void Start () {
    // Start camera
    var cameraTexture = new WebCamTexture();
    cameraTexture.Play();
    // Create a clock for generating recording timestamps
    var clock = new RealtimeClock();
    // Create a recorder
    var recorder = new MP4Recorder(...);
    // Record 150 frames
    for (int i = 0; i < 150; i++) {
        // Commit the frame to NatCorder for encoding
        recorder.CommitFrame(cameraTexture.GetPixels32(), clock.timestamp);
        // Wait for some milliseconds
        await Task.Delay(10);
    }
    // Finish writing
    var recordingPath = await recorder.FinishWriting();
}

Committing Audio Frames

NatCorder records audio provided as interleaved PCM sample buffers (float[]). Similar to recording video frames, you will call the IMediaRecorder.CommitSamples method, passing in a sample buffer and a corresponding timestamp. It is important that the timestamps synchronize with those of video, so it is recommended to use the same IClock for generating video and audio timestamps. Below is an example illustrating recording game audio using Unity's OnAudioFilterRead callback:

void OnAudioFilterRead (float[] sampleBuffer, int channels) {
    // Commit the audio frame
    recorder.CommitSamples(sampleBuffer, clock.Timestamp);
}

Easier Recording with Recorder Inputs

In most cases, you will likely just want to record a game camera optionally with game audio. To do so, you can use NatCorder's recorder Inputs. A recorder Input is a lightweight utility class that eases out the process of recording some aspect of a Unity application. NatCorder comes with two recorder inputs: CameraInput and AudioInput. You can create your own recorder inputs to do more interesting things like add a watermark to the video, or retime the video. Here is a simple example showing recording a game camera:

IClock clock;
IMediaRecorder recorder;
CameraInput cameraInput;
AudioInput audioInput;

void StartRecording () {
    // Create a recording clock
    clock = new RealtimeClock();
    // Start recording
    mediaRecorder = new ...;
    // Create a camera input to record the main camera
    cameraInput = new CameraInput(recorder, clock, Camera.main);
    // Create an audio input to record the scene's AudioListener
    audioInput = new AudioInput(recorder, clock, audioListener);
}

async void StopRecording () {
    // Destroy the recording inputs
    cameraInput.Dispose();
    audioInput.Dispose();
    // Stop recording
    var recordingPath = await recorder.FinishWriting();
}

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Requirements

• Unity 2018.3+
• Android API Level 21+
• iOS 11+
• macOS 10.13+
• Windows 10+, 64-bit only

Resources

• NatCorder Documentation
• Video Recording Made Easy
• Audio Workflows
• NatCorder on Unity Forums
• NatSuite on GitHub
• Email Support

Thank you very much!