There are two acceleration options on the Pi:
- OMXPlayer runs much of the player logic on the gpu which is highest performance option and can handle raw Blu-Ray quality videos. It does not support DVD menus or ALSA audio
- MMAL acceleration uses dvdplayer with hardware acceleration of the video codec. Performance is a little lower than OMXPlayer, but should still handle most 1080p content
By default both are enabled, and OMXPlayer acceleration will be disabled when not appropriate (i.e. DVDs with menus or when ALSA audio is enabled).
If you don’t play raw Blu-Ray quality videos then disabling OMXPlayer acceleration is an option which some users may prefer.