[mythtv-users] Slightly OT? - Video Quality
greg at kettmann.com
Wed Feb 21 16:41:03 UTC 2007
Does (or can) MythTV Hardware provide a "professional" quality image
(same as expected from TiVo, etc.) and, if so, must you buy high end
components? (Note, current tests were done under Windows and I've
returned the output/display card since I was unimpressed). I'm looking
for a sanity check here, before I start again.
Here are the, rather long, details.
I've been reading this forum and asking questions for 6 months or so. I
decided to take some baby steps toward building a unit. It's been a
disaster, but all HW and not specific to MythTV. It's a matter of
finding (working) suitable hardware, _with_ an AGP slot. Being a
typical geek I've a few systems floating around but so far nothing I
have will work. I finally grabbed my main desktop machine and ran some
tests using it.
I bought a video card which supports HDTV out, specifically it has a
dongle for Component (YPbPr) (an inexpensive implementation of the
GeForce 6200- Leadtech A6200TDH). I've a 3-4 year old Sony rear
projection big screen (53" - KP53HS10) that is capable of 1080i. I have
a high quality 6 foot YPbPr cable which connected to the dongle (the
dongle is 6" and it would be tough to get to the TV with less than say
4'). I was using Windows at this point, just playing around with
settings and presentation. What I found was discouraging.
The settings for 480i and 480p seemed to do the same thing on the TV.
It seemed to be 640x480. It suffered from what I think is called
"overscan" where the "picture" was bigger than the screen and I couldn't
scroll around. There was about 10-15% of the outer edge which I
couldn't view. More importantly, played videos (MPG's and AVI's) were
very dark when viewed with PowerDVD or MS Windows Media Player. I could
turn up the brighness (in PowerDVD and WMP) but then it tended to be a
bit washed out. Please note that I was using "downloaded" test video
segments (bit torrent), but they play just fine, with good quality, on
my laptop. Also, normal "Windows" brightness was just fine. It was only
the played video that was dark.
The next "usable" (no TV support for 720i or p) was 1080i. There was
significant "jitter", kind of an interlacing thing with the image
jumping up and down slightly (in Windows). No overscan. Windows screen
text nearly unreadable (small and slightly blurry). I was able to play
videos, again through PowerDVD and Windows Media Player and again they
were quite dark. The downloaded (supposedly HDTV) video tracks were
weak at best and certainly no better than what I saw with the regular
So, first observation is that my TV, although rated for 1080i, isn't
really up to the task. Not too big of a deal. I just means I forgo
HDTV for awhile. The new TV's are much better and support DVI anyway.
The video quality is an issue though. Is the "darkness" (of played
videos) caused by the video card? Normal Windows stuff was fine. It's
only the played video whether in a session or full screen. Might
another card provide better results? Does anyone have any practical
suggestions for a card (as in, I have a card with YPbPr output, which
I'm using, and it works well, the card is...)
How about the "overscan"? Are there settings in MythTV to fix that? It
appears I'll need to be using 480i or p but not until I can get around
the overscan. I know there have been topics on that so I'm confident
that particular issue has been discussed on these boards.
I just wanted a sanity check on getting started and so far it's not gone
well. I think I'll give up on HDTV for now and plan on just building a
good HD Front End later. For best quality I think I still want YPbPr
output since I've never been impressed with SVideo or Composite. I'm
just looking for a moderately priced way to start working with MythTV,
but so far I can't even find suitable hardware that gives results
equivalent to "regular" TV.
The next step will be a capture card. I'd figured on the PVR-150 but
those aren't conveniently available at the moment and people seem to be
getting the replacement card, which has no Linux Drivers available.
There is plenty of discussion on capture cards here.
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