Comment 1 for bug 1738907

If the delay increases over time then mathematically it sounds like the output is consuming bits slower than the input. So /maybe/ you have 48kHz audio being played at 44.1kHz but I would have thought that would be noticeable (sounding distorted - too low). And even if that's not the problem, the delay should hit a limit via some buffering limit, after which it turns into skipping (bug 405294).

Another thought is to see the suggestion in bug 1677202.