This post will attempt to provide a list of things that I have done in an attempt to improve the picture quality on my Hauppauge PVR-150. Hopefully it'll help anyone else who has this card and feels that the picture quality is somehow lacking and save them the time of crawling through the net and this forum looking for things to try.

My setup:

KnoppMyth R5E50
Hauppague PVR-150 (with the TCL M2523_5N_E tuner)
PIII 750 Mhz w/ 384mb RAM (no stuttering whatsoever, cpu utilization ~75%)
nVidia FX5200 w/ S-video to composite adapter plugged into TV.
27" CRT with normal analog cable.


Background:

Overall, my picture quality is quite good. In fact, it's better than it used to be. For some reason, my A/V system added snow to a whole bunch of channels and all of this static/snow is gone when I run the signal through my mythbox and then to the TV. That said, on those channels that are clear, I gradually began to notice a difference in quality. I've got a coax splitter set up so that I could quickly switch between the original analog signal plugged into the TV and the signal coming through the mythbox (technically speaking, the other output from the splitter goes to my VCR (which I use to tune) and a composite video cable goes to my TV from the VCR). Tuning to the same channel, I clearly noticed a difference in quality.

The difference is most notable when watching cartoons (Futurama or the Simpsons). After getting tipped off that something was wrong, I looked at other channels and noticed that they all looked a bit off. It's nothing obvious, but you get the feeling that something is wrong after watching for more than a few minutes. I settled on using the weather channel for all of my comparisons because the screen stays constant for long enough that you can really compare the two, and there is a good amount of color and text on the screen.

The Problem:

The picture doesn't look as vibrant/the colors are washed out/not quite right. There is NO static whatsoever. In more detail:

The colors themselves appear faded. Whereas on the weather channel, the color of the numbers for the temperatures superimposed on the map appear bright and vibrant, when watched through Myth they appear somewhat dull and faded. If you look at people's faces, on TV the skin color looks "pinkish" whereas through the MythBox it looks slightly orange/red.

When the people are standing in front of a blue screen on which a weather map is projected, they clearly look superimposed on normal television. Through the Mythbox though, they appear more blended and seem to fade into the background. Boundaries are not as sharp. One could say the picture looks slightly blurry; it feels like it lacks some detail/definition. When text is on the screen, it also appears slightly more blurry through the MythBox.

Of course, it's very difficult to describe what I'm seeing without posting some side-by-side screenshots. However, a digital camera would probably introduce it's own artifacts. The closest I can come to describing the difference is here (stolen from someone else who noticed the same thing): http://capnbry.net/~bmayland/fi/pvr150/pvr150-250.jpg. See how the Sci-fi logo is kind of blurry/faded/not as sharp or vibrant as that from the 250? Sufficce it to say, things don't look quite right, although they look very good and very close to normal TV.


Things to try:

While searching the web, here are some things I came across. Because MythTV, KnoppyMyth, and ivtv are all under such rapid development, I would ignore any post more than 6 months old. It's incredibly frustrating to read someone who appears to have the same problem as you, then see someone post a patch/fix, then see the original poster jump for joy at their problems being solved, only to realize that this patch was incorporated into the drivers over 3 months ago. That said, here are some current suggestions floating around. If you have the problem described above, hopefully some of these things will help:

1. Read this page: http://www.knoppmythwiki.org/index.php? ... lityIssues

It's pretty general and I didn't find it all that useful, but it does list a number of things worth trying:

a. Try changing both your display resolution (mine is set to 800x600 and changing it to 640x480 had no effect) and your capture resolution (I tried 720x480 with no effect). See the first post by hverkuil for some information why changing the capture resolution affects PVR-150 cards http://www.gossamer-threads.com/lists/mythtv/dev/247305 or the post by ethernut http://mysettopbox.tv/phpBB2/viewtopic.php?t=13097 (this is also in the general upgrade hints/hazards for R5E50 page, number 3 under known issues). I didn't notice much of a difference, though.

b. Use the nvidia-settings tool. This tool is a biggie for owners of nVidia cards like me. Try fiddling with the overlay settings and the TV-out settings. In particular, the flicker filter on the TV-out page is supposed to improve image quality. I definitely noticed a difference when using it, but calling it an improvement is questionable. I noticed that lowering the setting made the image a little sharper at the expense of making the text harder to read (all of the text would all of a sudden have these rainbow patterns start flowing through them). Raising the setting made everything slighly fuzzy, but the text became MUCH easier to read (especially on the program guide). No matter what I set the flicker filter to, though, text never looked as good as on normal TV and everthing still looked slightly blurry/fuzzy.

c. Use the Xv picture controls. You have to activate these first in mythtv setup->tv settings->play back->2nd page (Use Xv picture conrols). Then, while watching live TV, press the "f" key on the keyboard to cycle through settings to change and press the left/right arrow key to change them. I played with the hue a lot in an attempt to make the skin color line up better with normal TV but I never could get it quite right. People either looked too blue, too green, or too red. They never had that same "pink" flesh tone that they did on my TV.

2. Some people think this temporal filter setting change works wonders: http://mysettopbox.tv/phpBB2/viewtopic.php?t=13257. I didn't notice any difference with it, though.

3. In the general updade hints/hazards for R5E50 page (http://mysettopbox.tv/phpBB2/viewtopic.php?t=13108), number 4 under known issues looked particularly promising. I had to "touch /etc/modprobe.conf" before that script worked, but it made no difference for me after I tried it and rebooted to make sure the new module options took effect. This fix appears to be for static, though, so since I don't have any I'm not surprised it didn't do anything.

4. Try using Bob2 deinterlacing and XvMC for the MPEG2 decoder (under setup->tv settings->playback). Although it did slighly decrease my CPU usage (from 75% to 60%, it didn't do anything for problem with my colors/sharpness). It also made my OSD black and white, but there's a fix for that here: http://www.mythtv.org/wiki/index.php/XvMC. If you're going to use XvMC, make sure you've fixed the bug in number 10 in the known issues on the general updade hints/hazard for R5E50 page.

5. http://mythtv.org/pipermail/mythtv-user ... 17393.html hints at tweaking the registers on the capture card itself to improve quality (here too: http://capnbry.net/~bmayland/fi/pvr150). Something ommited from that page is that you first have to modprobe i2c_dev in order for the cx25840ctl program to work. I tried tweaking all of the values suggested there and the difference was very slight.


If you have any more suggestions, please feel free to post them. Maybe this thread can become the one stop picture quality post for users of the PVR-150. I know that would have been my life over the past week a lot easier.

At this point, I've basically given up on my PVR-150. Maybe this is just as good as it gets and I'm too much of a perfectionist. I just wish the picture quality coming out of my MthBox looked as good as what's plugged straight into my TV. I may yet cave in and buy a PVR-250, but that seems like a gamble to me since picture quality appears to be dependent on so many factors that there's no telling whether a 250 would be better or worse than what I have now. Since everything is working, maybe I should be grateful.

The incredible feature set of MythTV (I can't imagine living without Mythweb now), probably means I'll just deal with the inferior picture quality.

- Anything you can do with the Xv controls you should be able to do with the nvidia-settings utility. The Xv controls are just a convenient way of making adjustments in what you're watching.

- The first knob to try adjusting is the Gamma value using nvidia-settings. Before you do this, equip yourself with some of the test images that let you see if you're getting it right. There is a posting around here somewhere with pointers to several.

- Once you get the gamma ironed then you can start fiddling with brightness, contrast, hue, color saturation, ... Fiddling with these before you get the gamma under control is probably a waste of time.

- Experiment with the capture card adjustments which the G key brings up. If you've tested your video output with a DVD or the like and are pretty sure it's OK, this is the next place to look. Again, until you've got the output end sorted out with known apples to apples you're probably wasting your time here.

- Set up up your input and output resolutions to minimize scaling. Multiple scaling steps will suck the life out your signal like a spider sucks the juices out of a fly. Vertical scaling seems to be especially bad, if you are in NTSC land you really want an output resolution of 480 vertical. Yet again, other factors may mask this until you fix them.

- Lossy encoding is inevitably going to degrade the picture quality some, the higher the compression the more you'll lose. If you increase your resolution from the default 480x480 to 640x480 or 720x480 don't forget to adjust the bit rates too. Otherwise you're forcing up to a 1.5X greater compression ratio with a coresponding loss of quality.

Remember there's no silver bullet here. You may need to make a number of adjustments and even equipment improvements to get the picture you want.

I think the gamma control in nvidia-settings only controls the gamma for the X server (which would only affect X windows, not the TV-image). It doesn't have any effect on video overlay. For that, there's a seperate X overlay page, which doesn't seem to have any gamma control on it.

From personal experience, it controls both.

I thought I'd post an update since I finally fixed all of my problems. I know this isn't the solution that most people might be hoping for, but I ended up buying a PVR-350 and plugging it's composite out into my TV. The picture quality is now almost identical to that of my TV's internal tuner. Not quite the same, but close enough that it doesn't bother me anymore like it did with the PVR-150.

Yes, the PVR-350 is no longer supported and there's no guarantee that new versions of mythtv/ivtv will support it. Yes, the whole plug the audio out into the line-in of your soundcard is a big hack. Yes, the new video card I bought is now a $50 paper weight. Yes, I won't be able to do anything OpenGL intensive.

But given that I spend 90% of my time just watching tv or recorded programs, I think I can live with all of those flaws. I strongly urge anyone out there who is dissatisfied with the picture quality of their PVR-150 to try out the 350.

Note: although I wanted to try out the 250 as well, it's been discontinued and I waited a month for it to come in on backorder to no avail, so I just gave up and got a 350.

With recent drivers the _capture_ quality between the various PVR models is identical for all intents and purposes. The real change here is replacing the FX5200 _output_ with the PVR-350 output. If you've got a free slot that PVR-150 "paperweight" can be added to that box and will act as a second tuner with the same capture qaulity you have now. Since the output is being handled by the same card it will be the same as well.

s007, do you remember if you ever tried turning off deinterlacing when playing back tv recorded from your pvr150? I recently discovered that unchecking "deinterlace playback" with my pvr500 cleared up my slightly blurry, fuzzy picture. It didn't affect color fidelity, but it did improve sharpness.

FX5200 tvout svideo or composite
pvr500 Analog tuner
hd-3000 HDTV tuner
Over-the-air broadcasts only (usa ntsc, atsc)