Preview performance - reading the whole MPG per chapter!

aaronlawrence · Post by **aaronlawrence** » Fri Jan 09, 2009 1:12 am

I couldn't help noticing the incredibly slow preview performance.
I have one 2.8GB MPG captured from VHS, and added 18 chapters
- thumbnail menu
- no motion
- no sound.

When doing the menu preview, it took half an hour or so to start the preview.

I can see why, too: it read 68GB of data. That seems to be 18x2.8GB, so it would appear to be reading the entire video once per chapter, maybe just to get the thumbnail image!?

Post by **Ken Berry** » Fri Jan 09, 2009 1:19 am

That is certainly not the correct behaviour. Preview in the burning module will usually take a few seconds to activate, but usually no more than that. Have you recently manually updated DirectX to the November 2008 version? That will often correct problems with preview (that seem to have crept in with recent Windows updates)... See the top sticky on this Board for more on DirectX.

aaronlawrence · Post by **aaronlawrence** » Fri Jan 09, 2009 1:23 am

Ken Berry wrote:Have you recently manually updated DirectX to the November 2008 version?

Yes. The preview was not working at all prior to that.

Another factor may be that I adjusted each of the thumbnails to look at a frame inside the video, instead of at the chapter point. Maybe this exposes problems in the menu preview code.

This is X2 on a Dell laptop with 1GB RAM, running XP SP3.

Post by **Ken Berry** » Fri Jan 09, 2009 1:59 am

No, that should not affect anything. I always set the frame that shows in the thumbnail to a different point in the clip from the first frame, and preview is still quick.

aaronlawrence · Post by **aaronlawrence** » Fri Jan 09, 2009 5:30 am

Well, I don't know. It's still doing it. I tried switching off my anti-virus, didn't make any difference.

Well, I am doing something maybe considered a bit odd: the video resides on another computer over Ethernet. Before you laugh, it works pretty well for the most part, with no unexpected delays, and for capturing itself I work on the other PC (where VS6 is installed). I can't see why VS would behave differently on a network file though, and 68GB would be a problem whether local or network ... o well ...

Black Lab · Post by **Black Lab** » Fri Jan 09, 2009 3:22 pm

Well, the test may be to preview the video on the drive on which it resides.

Post by **Ron P.** » Fri Jan 09, 2009 4:00 pm

While using an Ethernet to do this, I'm not surprised at the slowness. Most of them are only 10-100Mbps throughput. I wouldn't count on the high-end of that, more often than not, it will be the lower end..

For video editing you need something at least as fast as what an internal bus will provide...

2Dogs · Post by **2Dogs** » Fri Jan 09, 2009 10:23 pm

aaronlawrence wrote:Well, I don't know. It's still doing it. I tried switching off my anti-virus, didn't make any difference.

Did you perhaps check the "Pre-render menu" box under the bottom left corner of the preview screen?

aaronlawrence · Post by **aaronlawrence** » Mon Jan 12, 2009 5:02 am

Well, it is operating at 100Mbps and I doubt the laptop's hard driver is hugely faster. But yes, the test will be to move the files to the laptop first and see if it makes any difference.

I don't think I checked Pre-render, but I will have to confirm that.