[mythtv-users] PVR250 Settings?

[papenfuss at juneau.me.vt.edu]

	As said before, bitrate is bitrate... doesn't matter the resolution.  
(except for the "scaling" option mythtv does which I turned off... I'd rather 
put in what bitrate I want).  The trouble is, if you've oversampled that much 
(720x480), there's not enough bitrate to adequately encode that many dots.  I 
believe MPEG uses blocks of pixels 8x8 or something like that, so you're 
allowing less bitrate for the information.

	I know this has been discussed before, but for a cable TV signal, going 
over 480x480 should be overkill.  The fact is, NTSC spec is for 330 analog 
lines, which translates into 440 lines at 4:3 ratio.  In other words, Capturing 
at more than 440x480 is a waste of bandwidth.

	Noise on the channel will definately cause problems with compression.  
Also, the mythtv scaling feature normalizes bitrate to capture area of 640x480.  
That means that 720x480 => 2200 -> 2500 kbps.  Looking at a relatively 
noiseless DVD video encoded at 2500 would be pretty crappy, let alone with 
noise.  My previous statement of 3500-4000 kbps miniumum for 720x480 still 
holds... shouldn't have too many compression artifacts.  That scales to about 
2600 for 480x480.

-Cory

 On Thu, 12 Feb 2004, Andrew Dodd wrote:

> Quoting Scott Pouliot <spouliot at scpsoftware.net>:
> 
> > Same here I use 2200 for my card as well.  I heard this is MPEG-2 quality.
> > I usually view the vids on my Windows XP box when I'm upstairs and bored
> > with work  ;-)
> I'm guessing you're not running at full resolution then...
> 
> Even on my cleanest channels, 2200 looks ugly as hell (compression artifacts) at
> 720x480.
> 
> I (believe it or not) run 7900 peak/6500 average.  Partly because many of my
> channels are noisy...
> 
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