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My HTPC setup: G35 based ASUS P5E-VM HDMI.

CPU tested: QX9650/Q8200/E8400/E8500.

Sample mkv file: BBC Life, scene of killer whales hunting the seal.

With windows media player and Coreavc decoder, both quad core CPUs cruise without CPU usage more than 60%. With E8400/E8500, max CPU usage is around 75%.

The same sample mkv file tested on a laptop with Broadcom Crystal HD decode card chokes a little bit with signs of dropped frames.

Then I inserted XBMC Live USB stick to boot into XBMC, it also chokes no matter which CPU I use. I understand XBMC can only use 2 cores, but with E8500 I really don’t expect that. I press the guide and keep tracking the CPU usage and dropped frame. Well, when it started to drop frames, cpu usage is about 30% and 90%. Apparently it is not CPU. Then I checked again and closely monitored the bitrate. I found that whenever bitrate reaches 40Mbps, XBMC start to drop frames regardless the cpu usage. This also applies to Broadcom decode card.

So here I am wondering, is it true that XBMC Linux/Live decoder also have a 40Mbps decode limitation? How about Windows version? I plan to try XBMC on top of Windows 7.

Thanks,
Roy

Any limitation is not actually Xbmc's. But Xbmc is limited by the chosen decoder. If using software decoding, the CPU is the limit. If using hardware acceleration, the hardware is the limit, and they all have different specs. The CrystalHD card, in particular, is rated up to 40mbps.

kraqh3d Wrote:Any limitation is not actually Xbmc's. But Xbmc is limited by the chosen decoder. If using software decoding, the CPU is the limit. If using hardware acceleration, the hardware is the limit, and they all have different specs. The CrystalHD card, in particular, is rated up to 40mbps.

I am not familiar but I also see 40Mbps limitition with pure CPU decoding, not the broadcom one. And CPU itself is not limiting the max bitrate. So I guess that is the soft-decoding limitation posed by the decoder XBMC chose.

kraqh3d Wrote:The CrystalHD card, in particular, is rated up to 40mbps.

That's the quoted literature spec, it can go faster. One thing that osx/linux don't do right now is dlddle the clock rates according to flavor of video, it's default is 160 and it can go to 200.