input_debug: add parameters to use white/pink/... noise data & file input

[rigid]

white/pink/... noise PCM data would be nice for testing, file input (raw PCM or wav) would be nice to do reproducable real-world tests

[kaixiong]

I am a little skeptical about having random noise as input, since it's impossible to tell when something goes wrong. Specific types of noise (pink noise, white noise, etc.) might be okay though.

[rigid]

Indeed, white noise would be more useful than random noise. (edited issue)

[kaixiong]

Is there some library we can use for noise generation?