* use a thread instead of short interval polling,
* do not assume latency is shorter than a period,
* negotiate sample format instead automatically,
* map all known ALSA formats to VLC codecs,
* negotiate channels and sample rate,
* partial support for 3-6 channels (missing preferences),
* negotiate buffer and period times according to caching,
* tolerate off-by-one period size due to rounding,
* use the "default" device by default rather than "hw",
* remove old-style hardware-only suggestions in debug messages.