[mythtv-users] Quality difference from WinTV2000 to MythTV

Fri Mar 5 09:40:19 EST 2004

<top posting due to peer pressure>

I think you have it backwards.  I don't think you can apply the
filters in Myth to a compressed stream but you can use the dnr
settings for the ivtv driver.  The dnr settings apply (AFAIK) only
to encoding, not decoding.  Try this link from the ivtv archive:

http://www.poptix.net/ivtv/Jun-2003/msg00095.html

It explains the use of the 3 dnr settings for the ivtv driver.  I
think at this point we are way OT for the Myth mailing list.
Do more research in the ivtv archives if you need more info
on dnr.  I think if you go back > 2 months you will find more
dnr info that is not driver development related (the driver
seems to be under EXTREMELY heavy development at the
moment).

BTW: I assume you are using ivtv 0.1.9 and not the CVS
version.  CVS is only for the extremely brave.

Again, HTH!

-- Harry O.

>From: Russell Gordon <ragordon at earthlink.net>
>Reply-To: Discussion about mythtv <mythtv-users at mythtv.org>
>To: Discussion about mythtv <mythtv-users at mythtv.org>
>Subject: RE: [mythtv-users] Quality difference from WinTV2000 to MythTV
>Date: 05 Mar 2004 07:36:14 -0600
>
>Thanks for the info.  My WinTV2000 is setup as DVD Standard, which is
>720x480 with a 4800kbps stream rate.  I setup myth to record at 720x480
>at 8000kbps and it did improve the recording quality more than I thought
>it would.  It still has a little noise compared to the WinTV2000.  I did
>read about the IVTV DNR and it seems that it is only for non-encoder
>cards, which leaves out the PVR-250.  In reading about the DNR with
>Myth, I was led to the videofilter section of the channel setup in
>MythWeb|Settings|Channels.  Does anyone know if this filter setting
>applies to the PVR-250?
>
>Thanks,
>
>Russell
>
>On Thu, 2004-03-04 at 11:45, Harry Orenstein wrote:
> > >From: "Russell Gordon" <ragordon at earthlink.net>
> > >Reply-To: Discussion about mythtv <mythtv-users at mythtv.org>
> > >To: <mythtv-users at mythtv.org>
> > >Subject: [mythtv-users] Quality difference from WinTV2000 to MythTV
> > >Date: Thu, 4 Mar 2004 08:40:38 -0600
> > >
> > >
> > >I have just setup my second Myth box and I have been recording a lot of
> > >shows.  I also have a Windows box next to my Mythboxes that uses the
> > >default software (WinTV2000) that came with my PVR-250 Rev1.  Having 
>the
> > >two boxes next to each with the same graphics card gforce440mx, same 21
> > >inch Dell FP2001 LCD monitors, and the same PVR-250 cards has allowed 
>me
> > >to notice a lower quality video being recorded in Myth as opposed to
> > >WinTV2000.  I noticed that the default in WinTV2000 was 720x480.
> > >Currently my Mythboxes are set to record at 480x480 at 2500kbps.  I 
>have
> > >read on earlier posts that increasing the bit rate and/or resolution
> > >does not yield that much improvement in video quality.  I have one
> > >channel that is a somewhat noisy and if I record the same show on both
> > >the Mythbox and WinTV2000, the Windows video will far surpasses the
> > >quality of the Myth recording.  It seems as though somehow the Windows
> > >recording is using some filtering to get the noise out. If I burn the
> > >Windows video to DVD in 1 hour mode and watch on a DVD player to a 27"
> > >TV via the svideo input, the Windows recording looks better than the
> > >original show did on TV!  What's up with the outstanding quality in
> > >Windows?  Are there any settings I can adjust in Myth to get to the 
>same
> > >level of quality?  I have also burned a Myth recorded video to DVD as
> > >well and it looks about the same as it did on the Mythbox watching the
> > >recording.
> > >
> > >Thanks,
> > >
> > >Russell
> > >_______________________________________________
> > >mythtv-users mailing list
> > >mythtv-users at mythtv.org
> > >http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> >
> > I don't see where you indicate the bitrate settings in WinTV2000.  What
> > bitrate settings are you using?  I use 1/2 D1 in both WinTV2000 and
> > Myth and find that the quality is roughly the same (I only have one box
> > so I have to dual boot to compare).
> >
> > There is a possibility that the Windows driver may be making better use
> > of the PVR-250 than the ivtv driver, but essentially both are setting
> > parameters and just streaming the mpeg output to a file, so there really
> > shouldn't be a huge difference.
> >
> > Strictly speaking, this is really a question for the ivtv mailing list, 
>not
> > Myth.
> > You may find better, more technically based answers to a question like
> > this if you post over there instead.  You may want to search the ivtv
> > archive for "dnr" (noise reduction), which has been discussed a great
> > deal in the past.
> >
> > As a slight aside, I have noticed some artifacts recording in Myth at a
> > resolution of 480x480 that seem to be better at 720x480, but that may
> > just be subjective.  I record in Myth only to timeshift things I cannot
> > watch when they are broadcast and only have my quality set to be
> > roughly the same as VHS quality (I watch and then delete).  If your
> > goal is to archive shows to DVD you may want to boost the bitrate and
> > resolution up (say, 8Mbps and 720x480) in order to get the best possible
> > source for transcoding and archiving on DVD.
> >
> > HTH!
> >
> >
> > -- Harry O.
> >
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