Question

I’ve been looking at the NAudio demo application “Audio file playback”. What I’m missing from this demo is a way to get hold of the samples while the audio file is being played.

I figured that it would somehow be possible to fill a BufferedWaveProvider with samples using a callback whenever new samples are needed, but I can’t figure out how.

My other (non-preferred) idea is to make a special version of e.g. DirectSoundOut where I can get hold of the samples before they are written to the sound card.

Any ideas?

Answer 1

With audio file playback in NAudio you construct an audio pipeline, starting with your audio file and going through various transformations (e.g. changing volume) along the way before ending up at your output device. The NAudioDemo does in fact show how the samples can be accessed along the way by drawing a waveform (pre-volume adjustment) and by showing a volume meter (post-volume adjustment).

You could, for example, create an implementer of IWaveProvider or ISampleProvider and insert it into the pipeline. Then, in the Read method, you read from your source, and then you can process or examine or write to disk the samples before passing them on to the next stage in the pipeline. Look at the AudioPlaybackPanel.CreateInputStream to see how this is done in the demo.