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

I use tvout feeding a modulator and mix it back in to my antenna coax system on an unused tv channel so I can watch mythtv on any tv in the house, with remote repeaters next to each tv.

The picture on the analog tuners was alway a little blurry, the interlacing on the tv always seemed a little off but I thought that was just the way it was. I tried all the deinterlacers available, finally leaving it on bob2x with xvmc enabled so the HD recordings worked the best.

Well, I just recently discovered that the analog channels look perfect on the svideo tvout if I uncheck deinterlace! I guess it makes sense because it is an interlaced signal in the first place and my desired result is to play it on an interlaced svideo tv, why de-interlace it and then let the nvidia driver re-interlace it (but not quite right) for the tv? Just don't deinterlace in the first place.

The problem is, I absolutely need deinterlace turned on for the HD stuff or else motion looks awful. So is there any way to automatically use deinterlace for HD playback and not use deinterlace for analog playback? I seem to recall there was a way to use different mpeg2 decoders based on source resolution, maybe that procedure could also be applied to deinterlacing, but I have searched and couldn't locate that info. If anyone knows where that post is, or some other possible solutions, let me know!
Thanks.

It makes sense that you will get the best result if you leave the video interlaced when sending video to an interlaced TV. I'm not sure why you would need to deinterlace the hidef video -- seems like it would be the same issue, but I would start by playing with the "video scan" menu entry that is available during playback. Here is what you do:

1. Set TV playback to bob2x deinterlacing in the setup screens.

2. When watching a recording (hidef or sdef) hit the menu button. One of the menu entries will be "video scan". The interesting pull-right menu choices are:

2a. Progress scan -- this will effectively turn off deinterlacing. My guess is that this will give you what you need for your std def recordings.

2b. deinterlace -- this will force deinterlacing. This should give you what you want for the hidef recordings.



Marc

Hi Mark,
Those menu selections you recommended do work and change deinterlacing appropriately. The biggest problem is that they are not automatic and not sticky, so it needs to be changed every time you watch an analog recording, even if the last watched recording was analog, too.

I see there is a keybinding available for "Next video scan overidemode". Perhaps I can assign it to a button on the remote to make setting it easier. I was really hoping for something automatic. Not everyone in the household can identify which recordings are analog and which are digital, but this should be a usable workaround.
Thanks!
P.S. I don't know why HD needs deinterlacing turned on. The 1080i show (ER) certainly does, I haven't checked the 720p stuff explicitly. I don't currently have 720p show saved. I think I'll grab one just out of curiosity.

jzigmyth, unfortunately, I haven't found a way to automate this stuff. I did post some instructions some time back that explained how to associate specific deinterlace filters to each channel during playback, but unfortunately, you can't do this with bob2x, and that's the only deinterlace filter that actually works reliably in NTSC land.

One thing that may help -- I posted some instruction on how to get the "video scan" options set properly with a single button push on the remote. The instructions I've given my family is, "If the video looks a bit "jerky", hit this button and it should get better. It's much easier than going through the 8 button presses that are otherwise required. For these instructions see the second post on this thread: http://mysettopbox.tv/phpBB2/viewtopic. ... highlight=

Marc

Nice tip! I like the idea of doing what essentially turns out to be macros in lircrc. I didn't know it was possible!

I did create a keybinding for "Next video scan overidemode" in Mythweb and assigned it to a remote button. It allows you to cycle through the different video scan modes while watching TV without bringing up a menu. Makes it easy to compare the different options instantly, although your method is the best to just go to a particular mode!

Back to the picture quality issue, watching analog with deinterlacing turned off results in a much clearer picture during essentially still shots but after watching a couple of shows, I realize that it introduces quite bothersome artifacts during sweeping motion.

There is something I don't get here. I record at 720 x480 with 3300 bit rate with a pvr 500 on R5F27. If I use Mytharchive to burn that show to dvd with no re-encoding and then play that dvd in my home dvd player it is absolutely crystal clear. Yet when I watch that same show through Mythtv on tvout I either have some fuzziness from interlace problems or motion artifacts, depending on which settings I use. I have to admit, I'm splitting hairs here. The fuzziness is totally tolerable and way better that watching a VHS recording. Its just that knoppmyth is so cool, it becomes an obsession to keep tweaking it better!

Guess I'll just have to go watch some more recordings! (for research purposes only)

Hummm... There are two classic root-causes for this problem:

1. Displaying interlaced video on a progressive scan device without deinterlacing

2. Displaying interlaced video on a progress scan device using a deterlace filter other than bob2x. The other filters (kerndint, LB, etc) will not deinterlace telecined video properly, which is common in NTSC land.

Edit after initial post: It would also help if you described the artifacts you are seeing.

What is your display device?

Marc

Basically it's because your DVD player has a hardware MPEG2 decoder that plays back your interlaced files without the need to deinterlace, and the TV out on your video card doesn't.

That's why the PVR-350's TV-out is nice when outputting SDTV to an interlaced TV... it has a hardware MPEG2 decoder.

It is probably the flicker filter on the nvidia that makes analog look bad when you don't deinterlace. The flicker filter averages adjacent scan lines. This is a Bad Thing(TM) for interlaced video when there is sideways motion. If you turn your flicker filter to 0 (using nvidia-settings), the video will probably look its best. The menus will probably look terrible though.

You might want to read these somewhat related threads:
http://mysettopbox.tv/phpBB2/viewtopic. ... =bob+uncle
http://mysettopbox.tv/phpBB2/viewtopic.php?t=10046