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· Registered
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Discussion Starter · #1 ·
I would like to stream video from a camcorder to a laptop using DV.

just bought a 200$ mini dv and am using a firewire cable and it works fine

i would like more than 30 frames per second and to reduce motion blur as much as possible because i am analysing runners

I was told that i should get shutter speed similar to

1/60, 1/100, 1/250, 1/500, 1/750 .......1/4000

100fps would be ideal

i dont need any features, heck a simple webcam with those specs i would be happy with

any suggestions, i am willing to buy used on line or what ever under 500$

thanks for your time

· Registered
28 Posts
First, shutter speed and frames per second (fps) are two different things. 1/500 sec shutter at 15 fps is perfectly possible. Shutter speed is the amount of time the sensor receives light for each frame.

You will off course like to have as short shutter speed as possible to get sharper images. With short shutter speed you will need good lighting.

With a DV cam I think you are stuck att 30 fps but note that video from a DV is interlaced, meaning that half of the horizontal lines will be exposed every 1/60 sec. With a good deinterlacer (bob deinterlacing) you can "simulate" the missing lines and get 60 full frames per sec.

There are some lowcost cams that can record at much higher shutter speeds and without interlacing. Check out Casio Exilim or Sanyo HD2000/FH1. Note that you will only be able to capture short clips (10 sec. on the Sanyo) and at reduced resolution. These cams will record to SDRAM cards (direct streaming to a pc is not possible).

To view the clip you will have to take the SDRAM card from the cam and put it in a SDRAM reader on your PC. It's possible to play the clips with the card in the cam using a USB cable but I think this involves plugging out the cable while shooting, so you might as well move the card around. You will also need a player on your computer to step frame by frame. Also note that the comression scheme (h264 on the Sanyo at least) makes it really hard for the computer to show the clip backwards. Maybe Casio uses mjpg, I don't know. mjpg is much easier to step back and forwards without too much hazzle.

If you use some special programs for analysis you have to check that the program can read your files (mp4 on the Sanyo). If they must be in AVI format you will have to convert them. There are some conversion programs (free) that will handle mp4 to AVI conversion very fast but you might find this complicated if doing it in the field...

Check the complete workflow with actual clips before buying anything. There are far too many things that can go wrong...
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