It's pretty much like mp3 in that it's dependant on the bitrate. The frame rate and size really don't matter as far as the file size is concerned, except that you would want to use a higher bitrate for larger frame sizes or faster frame rates.

Let's say you capture at 1Mbps video and 100Kbps audio (both rather low values, pretty much the low end of VCD quality). That's 1.1Mbps total, and doing the math comes out to 140.8KB/second or 8.06MB/minute.

DVD quality would be at least 5Mbps video and 224Kbps audio for a combined rate of 5.219Mbps, 668KB/second, or 39.1MB/minute.

Of course, there will be some overhead for file headers and such, but this is minimal compared to the media data itself.

Thanks for the replies this helps me out tremendously. So is it possible to elliminate the audio altogether to save on file size? From your explanation Chienworks, it doesn't look like the audio takes up a big part of the file size though. I'm mainly concerned with the video quality, but the final product will be put on DVD. So I'm looking for near DVD quality video, with no audio. I'm trying to get an estimate of how much hard drive space would be required to capture video for at least 30 days, running 24/7.

So using a rough estimate of 40Meg/min, my calculation comes out to 57.6 Gig/day x30 days/month= 1928 Gig/month.

So do you think it's possible to run 1928 Gig of multiple SCSI hard drives tied together and have them partitioned as one drive? Or have a way, where one fills up and it starts to record to the next?

What about file MPEG file size limits? Is there a limit?

Out of curiousity....what are you trying to capture?

I can't let you know the details. I just came up with this idea today and I'm investigating the feasibility of it right now, before I run it up the food chain where I work. Let's just say, if there's not too many road blocks with current technology, I've come up with an idea that will revolutionize the manufacturing processes in production plants. Patents pending :-)

I'm pretty clueless about MPEG specs, i only have empirical knowledge about them. However, i don't think they are size limited by format. You should be able to make them as big as the file system allows, and with NTFS that's mighty huge! I don't think you can eliminate the audio entirely. At least according to the Main Concept templates in Vegas the least you can do is 32Kbps, but there's no option for "no audio".

Lessee ... are there 160GB SCSI drives out there now? There must be. You can daisychain 13 of them on a single SCSI chain for 2080GB and you should be able to RAID these as one partition. That should just cover your need, barely.

I'm sure you're keeping in mind that DVDs only hold 4.7GB. That means you're going to have to split the file to put it on lots of DVDs when you're done. With that in mind, it might be better to come up with a scheme that splits your captures at some regular interval anyway, say once a day or so. This would avoild having a file so large it has to span multiple drives. It also means that if something goes wrong you'll only lose that one day rather than the whole month.

I know VidCap has the features for auto-splitting and auto-drive-rollover, but it won't capture in MPEG. There is probably software out there that does split & rollover MPEGs though. We'll just have to do some looking.

Leadtek makes a fairly inexpensive capture card. I use a VC100 card, which uses S-video or Composite for capture. The included software allows for file formats ranging from AVI to Mpeg-1/-2. You can also use it to not record audio. Newegg.com has the card for $28. (Last time I checked). I think the maximum resolution for recording is 640x480, and it did a nice job for my last project. Settings can also be tweaked on the card, such as brightness, contrast, bitrate, etc.

Rogue One

The ATI All In Wonder cards would be good for a capture card, and if you get iuVCR (www.iulabs.com for ~$20), you can specify max file size, max file time limit, and will auto rollover to next drive. It says it's compatible with the ATI AIW cards, but I don't know since I use an el cheapo $30 capture card.