Three hours to render a ten minute video?? That does not compute!

brightmonkey wrote on 8/16/2004, 9:57 AM

I used Camtasia studio to capture a ten minute segment of screen activity, then I used Camtasia Studio again to convert the captured output to 720x480 resolution. Then I imported the AVI output into Vegas 4 for editing and rendering. Imagine my surprise when I started the render process for NTSC DVD video stream and discovered that this simple ten minute video was going to take three friggin' hours to render!! Holy heaping render times, Batman!

I suspect it has something to do with using the Techsmith codec to capture and encode the AVI file, as well as to render the output to 720x480. I used this codec to save space on my hard drive, since the uncompressed files are HUGE, and I'm happy with the quality of the capture, but three hours to render 10 minutes?? That works out to about 18 minutes of render time per minute of video on a 1.2GHz XP machine with a gig of RAM. This seems rather excessive, considering that the codec is supposed to be lossless. The time to render doesn't seem to hinge on the number of frames per second I choose to record in Camtasia. Am I missing something here?

I'll live with the long render times if I have to, but for those of you who use Camtasia Studio, is there any way to reduce the final render time in Vegas? I do occasionally like to use my computer for other things, and at this rate if I do any long captures my computer could be tied up for days!

-Mario

Comments

JonnyMac wrote on 8/16/2004, 11:02 AM

My guts tell me that "lossless" codecs must work HARDER (more detailed analysis and calculations) to compress data without loss, hence the long render.

busterkeaton wrote on 8/16/2004, 12:07 PM

Are you familiar with doing mpeg renders? Mpeg (NTSC DVD) are always somewhat lengthy because you have to transcode. I suspect you are doing two transcodes first to avi then the to mpeg.

When you say 1.2 Ghz, what processor is that? AMD? Pentium or Celeron? It's not exactly state of the art.

Try a test and render to NTSC DV. Avi to avi should be pretty fast, but I suspect since you are using a "lossless codec" the first step is going to uncompressing from the lossless coded and then encoding to DV with the Vegas codec.

johnmeyer wrote on 8/16/2004, 12:07 PM

The first thing to do in any render time issue is to establish a baseline for how long a simple render -- without any Vegas fX -- will take. I suggest you start a new project, put your video on the timeline, select 15 seconds, and render that loop, using the rendering format you used for your three hour render. Doing this eliminates all the other variables. Do you still get a 18:1 rendering time? Also, what is the clock speed of your CPU?

stormstereo wrote on 8/16/2004, 1:27 PM

A long shot here - sometimes people have lenghty render times for no apparent reason. I've seen people write about AC3 renders taking waaaay too long. The solution was easy; reboot, start Vegas and try again. Voila, "normal" render times. Maybe something for you although I doubt it.

Best/Tommy

brightmonkey wrote on 8/17/2004, 12:10 PM

I've done a lot of rendering of DV-AVI to MPEG2 for output to DVD, which usually takes about 2-4 minutes to render per minute of video without any effects. In this particular case, I'm using Camtasia Recorder to record screen activity, using the encoder recommended by TechSmith (the company that makes Camtasia) to produce an AVI. This encoder produces a lossless AVI file that is very small when compared to uncompressed AVI. Then I use Camtasia studio (a separate module of the Camtasia studio suite) to take the AVI I just created and convert it to 720x480 resolution, once again making use of the same codec recommended by TechSmith. The resulting AVI is not much bigger than the original, and the conversion process is fairly quick since I'm using the same codec. It's when I bring this finished (and compressed) AVI into vegas for rendering to MPEG that the trouble starts. I suppose it's not really trouble, it's just surprising that the render to MPEG would take so long. My machine is a AMD 1.2GHz rig with a gig of RAM, and while it's certainly not state of the art, it's definitely no slouch.

I know that Spot, Gary and others use Camtasia, and I was hoping that one of them would chime in on their experiences with the software to find out if what I see is common or if I've missed something basic. If one of you Camtasia users reads this, I'd be interested to know what your mpeg render times are like when using AVIs created with Camtasia's Techsmith encoder. I would have posted this in the Camtasia forum, but since I'm working with Vegas I figure the odds of getting a useful answer are better here. To all of you that have taken the time to respond, thank you. I'm going to do some more testing and see what I come up with.

-Mario

jetdv wrote on 8/17/2004, 12:47 PM

Here's a reference point: The demo video of Tsunami which is about 8 minutes long took about 30 hours to fully render on an 800MHz Athlon using Vegas 4 and WinME.

vegasnewbie wrote on 8/17/2004, 1:08 PM

Since I bought a 3200 mHz CPU computer with 1536 megs memory DDR Ram 400 mHz, and two 200 GB Serial hard drives, I have had very good rendering times with Vegas 5. For example, it takes about 45 minutes to render 1 hour of video to MPEG-2 and about 70 minutes for 2 hours. I also have a GeForce 256 megs video card, but I am not sure whether this contributes to these good rendering times? Under a previous program I used with a 800 mHz computer, it took 10 hours to render 45 minutes of video, so it is a huge advance to be able to now render 2 hours of video in just over 1 hour.

Regards

Fred