IVSBackgroundImageSource

Objective-C

@protocol IVSBackgroundImageSource <IVSCustomImageSource>

Swift

protocol IVSBackgroundImageSource : IVSCustomImageSource

An extention of IVSCustomImageSource that is used to pre-encode an image or video to be rendered when the application goes into the background.

The timing information on the samples provided via onSampleBuffer is ignored on this image source, every image submitted will be encoded as the next frame based on the targetFramerate on the provided IVSVideoConfiguration.

Note

samples submitted will be processed on the invoking thread. For large amounts samples, submit them on a background queue.

Generating large numbers of samples from MP4 files is fairly straight forward using AVFoundation. There are multiple ways to do it in fact You can use AVAssetImageGenerator and generateCGImagesAsynchronously to generate an image at every 1 / FPS increment. Be certain to set requestedTimeToleranceAfter and requestedTimeToleranceBefore to .zero, otherwise it will batch the same frame multiple times.

You can also use an AVPlayer instance with AVPlayerItemVideoOutput and a DisplayLink, using the copyPixelBuffer API from the video output.

Both can provide a series of CVPixelBuffers to submit to this API in order to broadcast a looping clip while in the background.

  • Signals that no more images will be submitted for encoding and final processing should begin. Any errors that happen during this process will be emitted through the callback provided to createAppBackgroundImageSource.

    Declaration

    Objective-C

    - (void)finish;

    Swift

    func finish()

  • A convenience API that doesn’t require creating a CMSampleBufferRef to provide to the IVSCustomImageSource API, since timing data is ignored for the background source.

    Declaration

    Objective-C

    - (void)addPixelBuffer:(nonnull CVPixelBufferRef)pixelBuffer;

    Swift

    func add(_ pixelBuffer: CVPixelBuffer)

    Parameters

    pixelBuffer

    The PixelBuffer to be encoded.