I'm developing an application for Windows (7+) that uses Wasapi for simultaneous record and playback (VOIP style). I've set up two streams to the SAME device (one capture, one render), using exclusive mode access. Buffer sizes are exactly the same (10 ms worth of data, aligned properly).
Everything cranks along just great, but I've noticed that the rate at which data is being captured vs rendered is 'slightly' different, almost as if I were using two separate devices with different clocks. The capture stream supplies data at a slightly faster rate than the render stream consumes.
When my application is talking to another user, I'm wanting the user to hear themselves as part of the mix. This will be impossible without 'popping' occasionally if these two streams aren't perfectly synchronized.
Has anybody run into this 'out of sync same device' problem? Is there some basic concept I'm missing?
