[mythtv-users] PVR250 Settings?

[Pete's Mailing Lists]

Here's a link to a Hewlett Packard overview on how mpeg2 works.
http://pete1.no-ip.com/Mpeg%2bDVB/MPEGtutorial1.pdf
It's a bit of a simplification, but it gives an idea why you see much larger
differences at lower bit rates.

** As stated in earlier mails, transcoding to a different resolution at the
same bitrate will not reduce the file size. **

If you want a certain filesize then a rouge guide for mpeg2 is:-
2000kbs / 8bits per byte x 3600seconds x 204/188 (mpeg overhead) = 976MBytes
per hour.

Add a little for the file overheads and there's your 1GB per hour. (Are
there any in mythtv ?)
Subsistute your bitrate for the numbers and try it.

Find a bitrate that works for you and play around with the resolution.  As
you increase the resolution you will reach a point where the picture becomes
really bad.  Back off a bit until you can't see the difference. If your
video is noisy it will knacker even a profession mpeg encoder, so maybe a
video filter will help.

btw, I don't have a PVRx50 so I record at 2200kbs in mpeg4 at a resolution
of 480x576 (PAL).  I want all the lines but 480 horiz resolution seems good
enough.  Beats my VCR anyway !

Rgds,
Pete



-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org]On Behalf Of Jeff
Sent: 12 February 2004 15:02
To: papenfuss at vt.edu; Discussion about mythtv
Subject: Re: [mythtv-users] PVR250 Settings?



>  On Wed, 11 Feb 2004, Matthew Daubenspeck wrote:
>
> > I finally purchased a PVR250 and got it installed. Let the fun begin!
> >
> > What are other PVR people using for their bitrate settings? I want to
> > find a happy middle between space and quality, and would be interested
> > in finding out what the rest of you think...
> >

I use 352x480 for a resolution and 1331 (not scaled) for a bitrate.
I transcode these to 352x240 at the same bitrate.