Interface DefaultVideoTransformDeviceObserver

processingDidFailToStart will be called when VideoFrameProcessorPipeline could not start streaming due to runtime errors.

processingDidStart will be called when VideoFrameProcessorPipeline starts streaming.

processingDidStop will be called when VideoFrameProcessorPipeline stops streaming expectedly.

processingLatencyTooHigh will be called when the execution of VideoFrameProcessorPipeline slows the frame rate down by half.