Bit rate?

7 May 2007 4:29 PM

David Azose

I have an inexpensive card that allows me to transfer VHS tapes to the
computer. The program that comes with it does not give a lot of detail.
It asks for lots of parameters to be chosen. Most of them I can figure
out, but bit rate is not one I understand. What conditions go into
choosing a bit rate?

Thanks for any help.

David A

14 May 2007 2:25 AM

yeltz

David Azose wrote:

> I have an inexpensive card that allows me to transfer VHS tapes to the
> computer. The program that comes with it does not give a lot of detail.
> It asks for lots of parameters to be chosen. Most of them I can figure
> out, but bit rate is not one I understand. What conditions go into
> choosing a bit rate?
>
> Thanks for any help.
>
> David A

You haven't mentioned which card you're using, so I'll assume you're
capturing direct to MPEG-2.
A regular single layered DVD-r (DVD5) can store 1 hour of video at the
*full* DVD spec (audio + video) of 9.8 megabits/sec. If you want to
store 2 hours of footage then the average audio+video bitrate would be
4.4 megabits/sec.

Factors you should consider when choosing your bitrate include :
1. the picture quality of your original VHS footage.
2. whether the DVD will 'archive' your VHS or whether you're just
doing a quick transfer
3. multi pass variable bit rate vs contstant bitrate.

I'd recommend using AC3 or mp2 audio (instead of PCM audio) so that
you can allocate more bitrate to the video.

I'm not going to recommend a specific bitrate as it's really up to
your eyes what you consider to be a tradeoff.

Here's a link to a bitrate calculator where you can enter the length
of your footage and other criteria and it will provide you a
recommended bitrate.
http://dvd-hq.info/Calculator.html

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