[mythtv-users] video compression question

[Joseph A. Caputo]

On Friday 20 February 2004 15:35, Jarod C. Wilson wrote:
> On Friday 20 February 2004 12:11, Chris Petersen wrote:
> > > Isn't 5400kbps a little overkill for MPEG-4?
> >
> > No clue.  I just turned it up as high as I could with all of the
> > "quality" settings enabled, too.  My cable signal isn't the
> > greatest, so I figured it'd help keep codec-created noise at a
> > minimum.
> >
> > At least, I think that's how high it is.  Yeah, 4500-5500 depending
> > on the profile.
> >
> > Anyway, I'm really just curious whether higher-bitrate with
> > lower-res makes a difference vs higher-res + lower-bitrate ->
> > resize to lower-res.
>
> For mpeg4, 4500-5500kbps is definitely overkill. Most mpeg4 DVD rips
> look pretty much visually identical to the original at 3000kbps (or
> even less, but I rip at 3000kbps to err on the side of quality), so I
> wouldn't think anything higher than 2000kbps would show much
> difference for analog TV.

I agree.  I rip my DVDs at 2200kbps and they look great on my 60" rear 
projection screen.  Granted, most DVD rips use 2-pass encoding, but 
still, 2200-3300kbps is more than adequate for 640x480 TV encoding.  
I've heard some folks on the list say they use 4400kbps to guarantee 
the absolute best quality, but I think that's kind of pushing it, 
unless you're capturing at 720x480.  And (Chris), if you're going to be 
capturing at less than that 640x480 (say 480x480 for SVCD), be sure to 
check the "Scale bitrate for resolution" box in your recording 
profile... this lower the bitrate proportionally (the idea being that 
if bitrate X is what you want for 640x480, then you can achieve the 
same quality with a percentage of that bitrate proportional to the 
difference in capture resolutions).

-JAC