[mythtv-users] What CPU for HLS transcode performance

Andre mythtv-list at dinkum.org.uk
Wed Sep 5 12:40:51 UTC 2012

Hi, I've recently started experimenting with the HLS transcoding built in to 0.25 on two different backend machines and now I'm looking for some performance metrics before I upgrade my main backend PC.

The current backend PC is a Q6600 2.4Ghz C2D quad machine and this seems happy to transcode my h264 1080i recordings to 540p at 1500kbps in real time but anything more and it can't keep up. I have configured my main desktop Linux PC as a secondary backend and this seems much better, achieving 720p at 2500kbps but 4500kbps is beyond it. The low bitrate 720p is just about passable on an ipad screen but the higher bitrate looks much much better, between pauses anyway.

The desktop PC has an i7-860 clocked at 2.93Ghz and although only two cores are used and it looks like it's turbo boosting clock it's still not enough to get the job done. I'm considering upgrading the backend PC to Sandy or Ivy Bridge and I'm guessing that a >3Ghz i5 should be fast enough? The current i7 is managing ~23fps so not that far behind real time.

I'm wondering if anyone else has a backend PC that can produce decent bitrate 720p from h264 1080i 50hz recordings (BBC HD etc.) so I can decide if i5 3Ghz is enough or I have to pay the extra for 3.3 or 3.6Ghz and/or i7, maybe even an i3 is enough to get the job done?

Of course it would be better if an 3rd gen ipad would deign to play 1080i h264 directly but I don't think that will happen anytime soon.



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