Encoding times with i5 vs i7 processors.

[Warren Eagleton]

I recently upgraded my CPU from an i5-2500 to an i7-3770K. I am a bit disappointed and mysterfied at the apparent lack of a reduced encoding time from that when I had the i5-2500. I made a little 2min 45 second video with transitions etc as a test peice and found the i5 rendered at 1.2 times real time and the same video with the i7 was only 1.1 times real time. I noticed using Win 7 Task Manager that the i7 CPU was only peaking round 75 to 85% where the i5 was always round 98%. The video was in hi definition and was being rendered to Blu-Ray MPEG2 in Vegas Movie Studio Platinum 12. Can anyone suggest where I might be going wrong?? My desktop system specs as follows:- RAM 8G DDR3 1600mhz, Graphics card Nvidia GE Force GTX560Ti, Motherboard P67A-UD5-B3, OS Win 7 64bit, Western Digital hard drives 7200rpm. Any members encoding times for this setup would interesting to hear about, cheers.

[Steve Game]

Warren,

Just an observation, are you sure that the restriction is really the processor speed?
For example, you say that you have WD 7200 rpm drives. Are you rendering from one to the other, with neither of them being the system disk or is all video footage on one data disk so that disk has both read and write operations on different cylinders?
Also, have you checked whether all four processors are being used, (shows as eight under 'performance' tab of windows task manager)?
A processor can only go as fast as the I/O system can feed it.

[Warren Eagleton]

Thanks Steve for your thought provoking reply. You are correct I have my editing program on my SATA 3 boot drive & my rendering is stored on my other SATA 3 drive. I noted in task manager as you said I have all processors working. The i7 has 8 threads and it was this that I thought was the main advantage in the upgrade. Are you suggesting that I should store my render output on the same drive as my editing program?

[Eric Olson]

Originally Posted by Warren Eagleton

I recently upgraded my CPU from an i5-2500 to an i7-3770K. I am a bit disappointed and mysterfied at the apparent lack of a reduced encoding time from that when I had the i5-2500. I made a little 2min 45 second video with transitions etc as a test peice and found the i5 rendered at 1.2 times real time and the same video with the i7 was only 1.1 times real time. I noticed using Win 7 Task Manager that the i7 CPU was only peaking round 75 to 85% where the i5 was always round 98%.

The clock speed of the i5-2500 is 3.3Ghz; the clock speed of the i7-3770K is 3.4Ghz. Based on clock speeds you would expect a 3% improvement. However, your render takes 10% less time while using 20% less CPU. Therefore, your system is actually about 30% faster than it was. It would be interesting to compare the speed with hardware threading turned off.

If you are working with AVCHD or HDV source, then disk speed should not be a problem. Have you tried turning on or off GPU acceleration? Also try updating your Nvidia graphics drivers.

[Warren Eagleton]

Hi Eric, Thanks for your suggestions. I can confirm my scource is AVCHD footage from a SONY NX70P and that the setting for encoding is by CPU only as VEGAS apparrently uses the CPU in preference. When I changed to the i7-3770K I had to reinstall the video card drivers, not sure why but I was in Safe Mode at initial bootup, so drivers are OK now. I will follow up on hyperthreading to make sure all is OK. Thanks again.

[Warren Eagleton]

'FIXED' The medal goes to Steve Game for his suggestion that it may have been the writing to another SATA drive that was restricting the CPU data flow. Rendering the same video clip to the C:/ drive took .783 times real time, where as writting the render to the D:/ drive took 1,111 times real time. So the answer is render to the drive that the video editing program is on. Many thanks for the stear!!

[Jim Snow]

Originally Posted by Warren Eagleton

'FIXED' The medal goes to Steve Game for his suggestion that it may have been the writing to another SATA drive that was restricting the CPU data flow. Rendering the same video clip to the C:/ drive took .783 times real time, where as writting the render to the D:/ drive took 1,111 times real time. So the answer is render to the drive that the video editing program is on. Many thanks for the stear!!

I don't understand that. It goes contrary to everything I understand about this. I have always been under the impression that the best performance was realized when the render output drive was a seperate dedicated drive. Is is possible that your D: drive is very slow for some other reason?

[Leslie Wand]

+1 jim.

your experience is very strange / odd

[Eric Olson]

Glad you got it working!

[Warren Eagleton]

Hey guys it looks like I have to scrape off a bit of egg from my face! When I was playing around with this problem and got the first longer render time I did go into Options/Prefences/Video tab and noted that the setting for the 'max number of rendering threads' was set at 16. Which I didn't think was necessaryly of problem but I changed it to eight as the i7-3770 has 8 threads. After reading your lernard comments I checked the render times to the both drives and found they were actually the same now. When I put 'max number of rendering threads' back to 16 the render times went up again on both drives. I didn't know that it would have made a difference unless the thread count was less that the CPU's actual threads?? Well I live & learn although a tad slowly, cheers.