What causes stuttering playback if not CPU limited?

dalemccl · Post by **dalemccl** » Mon Sep 07, 2009 3:06 am

My old Pentium 4 PC's motherboard died so I upgraded the system to a Core i7 920 and hoped to see a major performance increase in Pro X2. As a first test I placed several 1920x1080 AVCHD clips totaling less than 1 minute in the time line, with no edits to the clips, no transitions or titles, etc. Just the raw clips.

I had SmartProxy disabled. I found that playback of an individual clip in "Clip" mode (the selection under the preview window) was smooth. But playback of the whole project time line in "Project" mode stuttered badly. Using XP's (32 bit) Windows Task Manager I could see that CPU usage never went above 19% during Project playback.

What else could be the bottleneck that would prevent smooth playback of the Project since apparently it is not the CPU that is limiting it? RAM is 6 GB of DDR3 1333 (of course XP only uses about 3 GB). The video card is an ATI 4350, which is pretty low-end among the newer video cards. The hard drives are two 1TB 7200 RPM SATA's with lots of free space.

(BTW, the project does play smoothly with SmartProxy enabled but of course the preview is lower in quality than the raw clips.)

Post by **Ken Berry** » Mon Sep 07, 2009 4:01 am

I don't know what the problem is, but I share it -- albeit with my Quad 6600 running Vista Ultimate 32-bit and 4 GB of RAM. My system also does not have a high end graphics card (ATI Radeon HD 2600 XT) but I don't think that's the problem either. I can play the same AVCHD on my HP laptop which only has a Core 2 Duo 2.0 GHz CPU and runs NVidia 7600 GS graphics... but it plays the AVCHD smoothly in both Play and Project mode... So unless it is a non-NVidia graphics thing, I am beat!

In any case, I have to say it is not a real biggie for me since I don't do all that much with AVCHD in the first place. All I really want to know is that my project is essentially all there. And I have found that when rendered, the end product (also AVCHD) also plays quite smoothly.

But damned annoying all the same...

dalemccl · Post by **dalemccl** » Tue Sep 08, 2009 6:10 pm

Thanks for the info, Ken. Since you have experienced this too, it tells me it must not be some oddity in my system, but rather it's just the way X2 works.

It is very odd to me that X2 can play an unedited clip smoothly in "Clip mode" and then by merely switching to "Project mode", the very same unedited clip will stutter during playback. It is almost as if X2 is executing different program code/instructions for Clip playback vs. Project playback.

Post by **Ken Berry** » Tue Sep 08, 2009 10:03 pm

I think it is. In Project mode it is doing a quick real-time temporary 'convert' to whatever your Project properties are (and these are highly unlikely to be AVCHD properties by default unless you have managed to set them that way). And the real-time bit with AVCHD is what is likely to be causing the jerkiness, regardless of how powerful your computer is...

jean-claude sarrazin · Fri Sep 11, 2009 4:00 pm

I changed my Pentium IV for a new AMD Athlon to get rid of these stalling problems when working with AVCHD files from my Sony HDR-XR200V. Effectively the CPU is not working so much but something happen somewhere where the video and the audio is affected to the point that I need to use the smart proxy set at 155 X 120. I'm still working with this issue... that's why I'm reading at your solutions
Thanks

Post by **Ken Berry** » Sat Sep 12, 2009 12:40 am

A Pentium 4 and AVCHD simply won't work -- the best you can do is with a P4 3.0 GHz with hyperthreading, which can at least run SmartProxy but can *never* play AVCHD smoothly, regardless of the program. I can't comment about AMDs but it would need to be equivalent to at least a decent Intel Core 2 Duo to be able to play -- and edit -- AVCHD...

jean-claude sarrazin · Tue Sep 15, 2009 2:03 pm

Thank you Ken for your reply.
Let me ask you something. In order to run AVCHD files from Sony HDR-XR200V with Corel VideoStudio® Pro X2 here is the Corel statement:
System Requirements: Non-Proxy HDV Editing
Intel Pentium 4 3.0 GHz, AMD Athlon XP 3000+ or higher with Hyper-Threading technology
1 GB of RAM (2GB or higher recommended)
16X PCI Express display adapter.
My new PC is Asus M3A78-EM AMD 780G PCIE with a AMD Phenom II X2 545 3.00G and 2 gigs and SATA2 640gigs, 7200 ... what I need more, I don't know. But in your replies I discovered that I was not using the smart proxy correctly. Sometime few files were in proxy and others not, cliking right on the files to force a proxy is really new to me and it is working great.
My other question. Compare to my Canon, the Sony HDR-XR200V has a low sound level. Is there a way to capture the audio signal by default when loading in Video Studio Pro X2 at a 400-500 level instead of 100.
Thanks.

Black Lab · Post by **Black Lab** » Tue Sep 15, 2009 2:31 pm

Is there a way to capture the audio signal by default when loading in Video Studio Pro X2 at a 400-500 level instead of 100.

No.

If you have a large project and need to raise the volume level I would wait until all my other editing is finished. Then I would go to Share>Create Sound File. This will create a WAV file of all the audio in your project. Now you can do a couple of different things:

1. Replace all the audio in your project with the new WAV file and use VS to adjust the volume.

or

2. Use a third party app (I use the free Audacity) and import the new WAV file, adjust the volume, then export it back to VS, replacing the original audio.