onPause can block the UI thread for seconds (ANR risk), worst in Quad mode #32

Decoder.onPause() stops everything synchronously on the main thread:

• RtspClient.stop() calls awaitTermination(2 s), and onPause calls it again for the decoder executor (2 s).
• In Quad mode, QuadCell.stop() calls awaitTermination(2 s) for each of the 4 cells.

The worker loops sleep with SystemClock.sleep(), which ignores interrupts. A cell in reconnect back-off (up to 30 s) or in a handshake read (5 s timeout) therefore uses the whole 2 s timeout. With 4 cameras offline, leaving the app can block the UI thread for about 8 s. Android shows an ANR after 5 s of blocked input.

Fix: signal the threads to stop and return immediately; release codecs once the threads have finished. Use interruptible waits (Thread.sleep, or a condition with a timeout) instead of SystemClock.sleep.