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Why is Vegas 9 preview SLOW when working with 2 tracks of Cineform AVI?
I am trying to speed up my workflow by transcoding AVCHD to Cineform AVI. Everything seems to load and playback a lot faster, UNTIL I add a second track of video. Once the preview gets to this point, it slows down to 10 frames! Is there a setting in Vegas that will get things back up to 29 frames? I was better off working with raw AVCHD if it’s always this slow.
THANKS!
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5 Replies
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What are you doing with the second track? PIP? blending? both take processing power. you can set the preview to preview-auto and that will help. Danny
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I’m working with two camera angles from a wedding ceremony. The second track is simply the cutaway shot. Got the main footage on track 1 and the secondary footage on track 2 and just cut out sections of the first one. I’m used to doing this with 4 or 5 video tracks of HDV and it never was this slow (running i7 processor). Tried preview AUTO (even Draft Auto) and it didn’t speed anything up. Any ideas?
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You’re probably thrashing you hard drive.
Cineform works out to about 15MB/s for 1080/60i video. That’s not a terribly difficult thing for a single, modern hard drive to stream. But once you stream two from the same hard drive, you’re seeking between the two files, and hard drive performance is going to get clobbered. 15MB/s + 15MB/s != 30MB/s when it comes to media streaming.
You may be able to prevent this by increasing buffers in Vegas (Preferences/Video/Dynamic RAM Preview), but I’m not exactly sure how Vegas uses the memory you give it. If you can, try each file on a separate drive.
You can certainly speed things up by lowering preview quality, too. Depending on what you’re doing in preview, you may be taking a big CPU hit, too. When you preview one file, you’re expecting the single CPU (Vegas doesn’t seem to use multithreading or any GPU accelerations in edit rendering… go figure) to decode one channel of video. No biggie. When you have two, layered, plus an effect… well, that’s more than twice the CPU load.
-Dave
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Thanks for the posts guys. Reducing the preview quality didn’t work for me. It was still skippy on the lowest quality (and I couldn’t tell what I was looking at). So I upped the RAM Preview and I’m back in action! It was set at something like 700MB, increased it to 6GB.
Can you expand on selective prerender? Where do I find that and what does it do? Thanks.
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Jay’s right about selective pre-render, at least as far as speeding up complex sections of video. If your whole project is too slow, this won’t help. But if you’re stumbling over some area of too much complexity, it’s just what you want.
Basically, you put the “loop area” over a section of your project. You get a pop-up that basically lets you select an output format — generally you’d choose the format you intend to render to later. Do this, and that trouble area is transparently replaced by the pre-rendered version.. fast now!
-Dave
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