This is a list of Android SoC's (System on a Chip, which is the CPU, GPU, VPU, etc. Also known as "chipsets") that will use hardware video decoding with XBMC. For most HD videos, hardware video decoding is necessary for smooth video playback. While some devices might be able to do SD and even some 720 content using software video decoding, hardware video decoding is considered essential for most Android devices.
1 How do I know what chipset I have?
- AMLogic - yes, in XBMC 13-alpha4 or higher when built with AMLcodec enabled (this is not default).
- Rockchip - yes, but some devices might need an updated firmware for smooth 1080 playback. 
- Tegra 3/4 - yes
- Allwinner - no. There's is some cedarv work, but it is unlikely it will make it into mainline XBMC. 
- Snapdragon - ?
- Freescale - ?
- OMAP - ?
- Samsung - yes?