AVI 2 gig limit

baron@barontayler.co

So what's the story on getting around the CamStudio 2 gig AVI limit? I want to record 4 hour seminars, and the resulting avi file would be about 12 gigs. I made a test recording today, 90 minutes in length, which should have resulted in a 4.5 gig avi file. About 14% of the way into processing, CamStudio displayed the "Can't merge audio and video" error message, and then a few minutes later displayed the window advising me of the location of the two files, one a .wav audio file, the other a .avi video file.

I installed VirtualDub, but (and I know this will sound stupid) I can't figure out how to "merge" the two files into one avi file. It looks like a handy program, but for those of us who know almost nothing about doing that kind of stuff, the directions are rather sparse. If someone who has used VirtualDub to merge CamStudio's .wav and .avi files would post step by step instructions, it would be very much appreciated.

If there are any other "work arounds" to the 2 gig limitation, please don't keep them secret.

Thanks

booklover

Baron, I saw your earlier question but had to do some captures, which is all I've done so far with CamStudio, since I couldn't remember doing anything special. On the short captures I did to refresh, I did nothing -- the temporary files -- the video and audio merged themselves.

The longest capture I've done -- unless I erased the avi's after converting them to wmv's to upload to YouTube -- was 3.5 GB, which VirtualDub opened with no problem. However, chances are it didn't have sound, since the site where I do my captures hasn't often had the sound turned on.

I'm still mostly using CS 2.0 since for what I do -- captures, which I then piece together with Windows Movie Maker -- it's fine.

I'm having trouble with my Windows 7 right now -- it has a program that didn't fully install and now won't uninstall -- so it won't capture sound even though it used to. The XP one is still capturing -- video and audio -- fine.

It may be that there are limits that I didn't run into that you're encountering. It might be worth doing some captures on some of the videos everywhere on the web and see if there's a limit.

In one of his posts Terry -- or maybe it was someone else -- mentioned another program that will break the 2GB avi limit. Unfortunately I didn't bookmark that post or note the name of the program but it might be worth looking for. I'm under some time pressures right now or I'd try to find it. Terry will probably remember it.

Jo

baron@barontayler.co

Hello Jo,

I just finished spending the whole day running running various captures. My goal, at the very least, is to be able to capture 2 hours and end up with a file of no more than 2 gigs.

Keep in mind that I'm capturing conferences that have people talking over Paltalk, and the attendees are viewing stuff online, including PowerPoint presentations which have been converted to web sites. The amount of videos being displayed by the people talking is minor.

I made a very important discovery early on: If you capture streaming videos, then your CamStudio files are going to get very large, very fast. So I started to work my way down the "quality scale" to see what the point was were I could get 2 hours in a 2 gig file.

(Interesting note: There was no discernible difference in file size between 32 bit and 16 bit color. I ran the test 3 times, capturing identical stuff, the only difference being the 32 or 16 bit color setting. No difference worth mentioning.)

To make a long story short, I found that by setting the capture rate to 20 frames per second, a 2 hour capture came out to be 2.14 gigs. The nail biter was to see if CamStudio would process the two temporary files into one avi file, even though it was over the 2 gig limit. The answer is "Yes." It created the avi file. As reported by others, the avi file will not play, due to some "corruption" created by CamStudio due to its size. I then processed the avi file through AVC, (leaving the 1360x768 screen size untouched), and bumped the frames per second up to 25. After processing, the new avi file was only 442 mb in size (almost an 80% reduction), and it runs great in any player.

I realize that 20 fps is not a high enough speed for capturing a lot of streaming video and "action" stuff, but for recording conferences with a lot of talking about "slides" on the screen, it's perfect.

Tomorrow I'm going to push the envelope a bit, and try a 2 hour and 15 minute capture, and if that works, a 2 hour and 30 minute capture. I have to prepare for the inevitable fact that some of the speakers go over their allotted time. Eventually I know I'll hit that "wall" where CamStudio will tell me it can't merge the audio and video. I'll let you know how it goes.

Baron

TerryBritton

baron,

Here's a repeat of another reply:

I'm working on a solution to the 2-gig limit. (Sorry, but this is moving week, so I've been very busy along with work at the same time...)

The easiest is to run two separate instances of CamStudio and start the second just before ending the first, alternating, and editing the resulting recordings together later in the editor of your choice. CamStudio 2.0 can run separate instances (that is, you can start the program up more than once, and the new one runs in its own process). CamStudio 2.5 and 2.6 have to be run concurrently with a 2.0, I believe. I'm going to do some experiments and see how this goes. This will avoid the entire issue of repairing a broken AVI that went over the 2-gig size limit.

Why are you capturing so many pixels at once? That practice is making you run-up to that 2-gig limit much faster. Can you set your display settings at a much smaller resolution and capture that via the full-screen region instead?

As to this note:

"(Interesting note: There was no discernible difference in file size between 32 bit and 16 bit color. I ran the test 3 times, capturing identical stuff, the only difference being the 32 or 16 bit color setting. No difference worth mentioning.)"

- that does not make any sense to me. Are you certain that you had shut down and re-started CamStudio after the switch to 16-bit? Sometimes (with some drivers) a computer re-start is necessary to actually register the bit change in your programs. I know this, because I got "caught" by the same seeming situation as you did.

Terry

nickthegeek

Baron

If all you're seeing on screen are just the slides or a person at a podium with slides with minimial movement, you could probably drop the capture rate down to every 100ms with a playback rate of 10 fps.

Also dropping the audio quality down as low as you can stand can significantly reduce end AVI size.

Here's how you can estimate the final size of the audio data:

The size of the audio stream is the audio bitrate multiplied by the duration and divided by 8: size (bytes) = bitrate (bps) * duration (sec) / 8 .
(Courtesy: http://help.encoding.com/idx.php/0/012/article/What-Audio-bitrate-kbps-value-should-I-use-and-how-will-it-increase-file-size-and-quality.html)