This paper describes the implementation of a streaming spectral
processing system for realtime audio in a consumer-level onboard
GPU (Graphics Processing Unit) attached to an off-the-shelf
laptop computer. It explores the implementation of four processes:
standard phase vocoder analysis and synthesis, additive synthesis
and the sliding phase vocoder. These were developed under the
CUDA development environment as plugins for the Csound 6 audio
programming language. Following a detailed exposition of
the GPU code, results of performance tests are discussed for each
algorithm. They demonstrate that such a system is capable of realtime
audio, even under the restrictions imposed by a limited GPU
capability
