Buffers

In this example, we will show you how to use the CreativeEditor SDK's CreativeEngine to create buffers through the editor API. Buffers can hold arbitrary data.

Setup#

This example uses the headless CreativeEngine. See the Setup article for a detailed guide. To get started right away, you can also access the block API within a running CE.SDK instance via cesdk.engine.block. Check out the APIs Overview to see that illustrated in more detail.

Limitations#

Buffers are intended for temporary data only.

Buffer data is not part of the scene serialization
Changes to buffers can't be undone using the history system

JavaScript


createBuffer(): string

Create a resizable buffer that can hold arbitrary data.

Returns A URI to identify the buffer.

JavaScript


destroyBuffer(uri: string): void

Destroy a buffer and free its resources.

uri: The URI of the buffer to destroy.

JavaScript


setBufferData(uri: string, offset: number, data: Uint8Array): void

Set the data of a buffer at a given offset.

uri: The URI of the buffer to update.
offset: The offset in bytes at which to start writing.
data: The data to write.

JavaScript


getBufferData(uri: string, offset: number, length: number): Uint8Array

Get the data of a buffer at a given offset.

uri: The URI of the buffer to query.
offset: The offset in bytes at which to start reading.
length: The number of bytes to read.
Returns The data at the given offset.

JavaScript


setBufferLength(uri: string, length: number): void

Set the length of a buffer.

uri: The URI of the buffer to update.
length: The new length of the buffer in bytes.

JavaScript


getBufferLength(uri: string): number

Get the length of a buffer.

uri: The URI of the buffer to query.
Returns The length of the buffer in bytes.


// Create an audio block and append it to the page
const audioBlock = engine.block.create('audio');
engine.block.appendChild(page, audioBlock);

// Create a buffer
const audioBuffer = engine.editor.createBuffer();

// Reference the audio buffer resource from the audio block
engine.block.setString(audioBlock, 'audio/fileURI', audioBuffer);

// Generate 10 seconds of stereo 48 kHz audio data
const samples = new Float32Array(10 * 2 * 48000);
for (let i = 0; i < samples.length; i += 2) {
  samples[i] = samples[i + 1] = Math.sin((440 * i * Math.PI) / 48000);
}

// Assign the audio data to the buffer
engine.editor.setBufferData(audioBuffer, 0, new Uint8Array(samples.buffer));

// We can get subranges of the buffer data
const chunk = engine.editor.getBufferData(audioBuffer, 0, 4096);

// Get current length of the buffer in bytes
const length = engine.editor.getBufferLength(audioBuffer);

// Reduce the buffer to half its length, leading to 5 seconds worth of audio
engine.editor.setBufferLength(audioBuffer, length / 2);

// Free data
engine.editor.destroyBuffer(audioBuffer);