[mythtv-users] HD Compression Artifacts

Steven Adeff adeffs.mythtv at gmail.com
Fri Mar 23 13:31:06 UTC 2007

On 3/23/07, ryan patterson <ryan.goat at gmail.com> wrote:
> On 3/22/07, John Goerzen <jgoerzen at complete.org> wrote:
> > Hi,
> >
> > I have a pcHDTV 3000 and am using it for over-the-air HD broadcasts.
> >
> > I have noticed recently that during NCAA games, where there is on-screen
> > action -- even some sort of graphic moving around -- that classic MPEG
> > compression artifacts are visible around it on the TV.  I have no
> > explanation for this.  It seems like with HD, we shouldn't have to deal
> > with that sort of thing, yet there it is.
> >
> > Switching between ffmpeg and libmpeg2 decoders makes no difference.
> >
> > Is this an inherent problem with HD?  Or perhaps something specific to
> > how CBS is airing the NCAA games?
> >
> You are seeing compression artifacts from the original broadcast source.
> There is nothing wrong with your setup.  The problem is the hardware CBS
> uses for compressing the video stream in real time for live viewing.
> Prerecorded shows are compressed beforehand using a more time intensive
> compression system.  As time goes by hardware for real time mpeg-2
> compression should get more powerful.  So ten years from now these
> compression artifacts on live events should be gone.

It's not the hardware being used to compress, its the bitrate. I see
compression problems on regular tv shows all the time in high movement
scenes (try watching an episode of Las Vegas the fast pans/cuts induce
major mpeg blockiness, or a late night show music segment, the blue
lights screw with the mpeg encoders).

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