[mythtv-users] Quality difference from WinTV2000 to MythTV

[Harry Orenstein]

>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
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>mythtv-users mailing list
>mythtv-users at mythtv.org
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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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