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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.

fun createBuffer(): Uri

Create a resizable buffer that can hold arbitrary data.

  • Returns a uri to identify the buffer.
fun destroyBuffer(uri: Uri)

Destroy a buffer and free its resources.

  • uri: the uri of the buffer to destroy.
fun setBufferData(
    uri: Uri,
    offset: Int,
    data: ByteBuffer,
)

Set the data of a buffer.

  • uri: the uri of the buffer.

  • offset: the offset in bytes at which to start writing.

  • data: the data to write. Note that it has to be a direct ByteBuffer, created either via

ByteBuffer.allocateDirect or via JNI NewDirectByteBuffer API.

fun getBufferData(
    uri: Uri,
    offset: Int,
    length: Int,
): ByteBuffer

Get the data of a buffer.

  • uri: the uri of the buffer.

  • offset: the offset in bytes at which to start reading.

  • length: the number of bytes to read.

  • Returns the data read from the buffer or an error.

fun setBufferLength(
    uri: Uri,
    length: Int,
)

Set the length of a buffer.

  • uri: the uri of the buffer.

  • length: the new length of the buffer in bytes.

fun getBufferLength(uri: Uri): Int

Get the length of a buffer.

  • uri: the uri of the buffer.

  • Returns the length of the buffer in bytes.

Full Code#

Here’s the full code:

// Create an audio block and append it to the page
val audioBlock = engine.block.create(DesignBlockType.Audio)
engine.block.appendChild(parent = page, child = audioBlock)


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


// Reference the audio buffer resource from the audio block
engine.block.setUri(
    block = audioBlock,
    property = "audio/fileURI",
    value = audioBuffer
)


// Generate 10 seconds of stereo 48 kHz audio data
val sampleCount = 10 * 48000
val byteBuffer = ByteBuffer.allocate(2 * 4 * sampleCount) //2 channels, each 4 bytes
repeat(sampleCount) {
    val sample = sin((440 * it * 2 * PI) / 48000).toFloat()
    byteBuffer.putFloat(sample)
    byteBuffer.putFloat(sample)
}
// Assign the audio data to the buffer
val data = ByteArray(byteBuffer.capacity())
byteBuffer.position(0)
byteBuffer.get(data)
engine.editor.setBufferData(uri = audioBuffer, offset = 0, data = data)


// We can get subranges of the buffer data
val chunk = engine.editor.getBufferData(uri = audioBuffer, offset = 0, length = 4096)


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


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


// Free data
engine.editor.destroyBuffer(uri = audioBuffer)