[mohitmun]

Would this make it possible to build active noise cancelling using software?

[taneq]

I wouldn't think so. If your cancelling signal is half a period out, you'll double the volume instead of cancelling it. That suggests the required latency is on the order of microseconds, not milliseconds.

[iandcoleman]

Android already has an aec module that you can use. It's timestamp based using the timestamp calls to ALSA to perform the cancellation