[mythtv-users] Video Quality

[Alan Snyder]

> > 
> > With a dirt-cheap bt878 capture card, generic
> > GEForce-2 video card, and mid-90's 27" TV, with myth doing 
> MPEG-4 at 
> > 640x480, 2200kbps, the difference between live TV through myth and 
> > live TV off the cable is noticable but not bothersome.  The CNN 
> > "crawl" is a little jumpy.  There's some loss of detail in the 
> > highlights (I think that might be a bt878 chipset issue).  Up close 
> > (closer than I watch), some blockiness is present 
> (replacing the less 
> > noticable noise in an analog picture).  Football can seem harder to 
> > follow, probably because of the limitations of the compression 
> > settings to handle the frame-to-frame changes in content.  But 
> > overall, the difference is similar to the difference between a good 
> > cable signal and an "OK" cable signal.  I do notice that for certain
> > channels where the cable signal is weaker, the noise in the 
> > original results in more artifacts in the processed video.
> > This is most likely because the compression scheme needs to
> > deal with all that extra "information."
> 
> Before I go through and do this I need to be clear on this 
> one- is watching sports not very good through mythtv?  If I 
> am watching hockey or football on a large TV, having the 
> ability to pause live TV would cause large amounts of 
> distortion?  How noticeable is the difference between a 
> recording and live TV when watching sports?  Thanks for any 
> information.

Since I posted this, I should respond.  My expectation is that if I
had a faster CPU and could go to the 3000kbps range, these artifacts
of the compression scheme would go away.  At some point, the difference
between the original and the compressed copy becomes indistinguishable.

People who have PVR-250's can tell you whether the card essentially
gets to the quality of a well-encoded DVD movie.  I would *guess* that
it can.  I also expect from my experience with my 1 GHz system that
a 2 GHz system would probably make my results indistinguishable from
the original.

Others have pointed out one (probably not the only one :)) shortcoming
of my original comments:  The filters provide an opportunity to
*improve* the picture.  You cannot recover lost information.  But 
that doesn't mean that certain filters won't make it *look* better
than the original.