[Gllug] Hardware requirements for video editing?

Chris Bell chrisbell at overview.demon.co.uk
Fri Apr 11 08:22:29 UTC 2003


On Thu 10 Apr, Rich Walker wrote:
> 
> Chris Bell <chrisbell at overview.demon.co.uk> writes:

> > 
> > 
> > Do standard camcorders aimed at the UK market run at 30 rather than 24/25
> > frames per second?
> 
> I don't know; that's one of the speeds in the Firewire spec, ISTR. From
> /usr/include/libdc1394/dc1394_control.h:
> 
   I was just trying to figure out the optimum screen rate. I think that
computer screen images have shorter decay times than ordinary TV screens, so
do not reduce flicker as much. The optimum would probably be locked to twice
the picture rate, as long as this does not result in obvious beat patterns.
Standard UK analogue broadcast is 50 interlaced frames per second, 25
pictures per second, and everything used to be locked to 50Hz mains to
reduce the effects of mains hum.
   Broadcast video is compressed as near as possible to the final
transmitter so as to avoid degradation due to multiple processing, and the
equipment is designed to cope with very high data rates. There are systems
specifically designed as instant replay recorders using a huge box of hard
disc drives, able to store 20 minutes of sound and video, as well as slow
motion replay systems using modified cameras and videotape recorders running
at 3 times the normal rate, so that the replay can be slowed without too
much jitter, but unfortunately they are not within the available budget.


-- 
Chris Bell


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