[mythtv-users] Is my MythTV an UpConverting DVD Player?
jonner at teegra.net
Fri Nov 9 03:41:41 UTC 2007
On Nov 7, 2007 10:32 PM, MythTV User <mythuser at mydean.com> wrote:
> I set my Xorg to output at 1080p which my 46" LCD displays nicely, with
> 1:1 pixel mapping. Is playing DVD discs using xine (or internal dvd player)
> with anamorphic setting on equivalent to playing the DVD in an
> upconverting/upscaling player? If not, is this possible?
What exactly does the upconverting/upscaling player do? What a typical
software player such as Xine, Mplayer, or MythTV does is to display images
using the XVIDEO X11 extension. This allows the player to send frames of
video in the same uncompressed format contained in the encoded video to the
X11 server. The server then typically uses the video hardware to convert the
images to an RGB colorspace and scale it to the desired size, which might be
1920x1080 or 1280x720. That certainly sounds like upscaling or upconverting
to me, but I don't know how the marketroids use those terms.
I've read that the scaling algorithms implemented in video hardware may not
be the best quality ones. I know that mplayer has several scaling algorithms
it can use internally that are supposed to give better quality results at
the cost of more CPU time (since the video card isn't doing the scaling) and
you can probably also use software scaling in MythTV with the right playback
filter, though I haven't tried it. I haven't personally noticed the
difference between the quality of the video card's scaler and a high quality
software scaler, but someone with better vision and/or a better display
Another commonly used conversion is deinterlacing, which MythTV, Xine and
Mplayer can all do. Thankfully this is usually not needed to play DVD
movies, since a properly encoded movie will be progressive frames with MPEG
flags that also allow it to play well on an interlaced display. What I can't
figure out is why the same technique isn't used to encode the vast majority
of HD shows I see that are clearly from progressive sources.
In any case, when I play DVD movies with any software player, the image
quality looks great on my 26" 1366x768 LCD panel. Though there is noticeably
less detail than a 720p or 1080i show, it looks much better than regular
NTSC and most 480i ATSC shows.
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