Using a ordered ring buffer and a thread pool, the color space
conversion is not multi-threaded based on frames. I tried
to implement slice based threading, but libswscale did produced
highly distorted pictures without obvious reason.
This approach introduces some more "lag" when decoding and skipping,
but shouldn't be affect the user negatively, since movie
watching is not lag sensitive, as long as the A/V is synchronized.
Change default to software decoding.
SW decoding is the most robust and fasted method of decoding right now.
Users should enable hw based decoding if their system requires it
and it's actually beneficial for them.
Fix deadlocks when seeking and decrease RAM usage.
Decrease memory allocation by reusing AVFrames.
