Hi.

I'm running R5D1 on a "near-Dragon" system. I have the ASUS 6200TC video card and the MSI K8N Neo4 Platinum motherboard.

When I play back a 1080i recording through my 1080i modeline, the interlaced fields are obviously swapped. The motion looks really strange and about half the time when there are scene changes you can see a field from the new scene, a field from the old scene, and then fields from the new scene. That is, scene changes flicker between the old and new scene for a moment.

This happens for XvMC or libmpeg2 or Standard playback. If I switch to a 1920x540p modeline and run Bob deinterlacing, it looks pretty good, but I wanted 1080i b/c then I wouldn't have to muck with the deinterlace settings each time I want to watch a 1080i show, and I would also be sure that the upper scanlines were drawn below the lower scanlines (and with 540p/Bob it's a crapshoot).

My modeline is:

but I've tried several and all have the same problem.

Thanks for any help.

You're probably going to need to provide more info to get some help on this one, such as:

1. What version of knoppmyuth

2. What video card?

3. What video driver and version?

4. What output device are you displaying on?

5 What type of connection to the video display are you using?

In terms of fiddling the deinterlace settings -- I've documented a technique to automate that process in this thread http://mysettopbox.tv/phpBB2/viewtopic. ... ght=filter


Marc

R5D1

ASUS Extreme N6200TC256/TD


NVIDIA 8774

Sony KD34XBR960.

An VGA->Audio Authority 9A60->Component. Since the signal is analog I'm sure the fields are probably swapped when they come out the VGA port on the card.

My HD video connection has always been either VGA or DVI -- never used the Audio Authority 9A60, but there are others on the fourm who have. Perhaps one of them has some insights into this...

Marc

Well, I was pretty sure it had nothing to do w/ the 9A60, so I connected my box to a ViewSonic P95f+ multiscan CRT (directly via VGA), and ran my usual 1080i mode. The problem persists.

Marc, if you run a 1080i modeline without problems, could you give it to me, and I can see if the modeline has anything to do with it?

Sure. I don't use 1080i anymore as I know connect to me HDTV via DVI, and the DVI connection only understands 720p, but I used the following modeline for several months successfully with the VGA connection:



Marc

No good. With your modeline I still have the problem.

Leif

Maybe it's something else. Consider:


1. utilities/setup->setup->tv_settings->Playback->Screen 1 (General playback):
Do Not Select the following: "Enable OpenGL Vertical sync for timing", Enable realtime priority threads", "use video as timebase".

Make sure you do select "Extra Audio Buffering".

2. utilities/setup->setup->tv_settings->Playback->Screen 8 (Overscan): Make sure all of these are set to "0".

3. utilities/setup->setup->Appearance: Tell me how you have screen 3 (video mode settings) configured.

Marc

Previously I had this just as you say, except for "Enable realtime priority threads," which I have now unchecked.


This is how I have them set.


Separate video modes for GUI and TV playback is checked.

GUI: 1280x720
Video Output: 1920x1080
Rate: Any
Aspect: 16:9

In X / In Y / Output / Rate / Aspect
1920 / 1080 / 1920x1080 / Any / 16:9
1280 / 720 / 1280x720 / Any / 16:9
0 / 0 / 400x300 / blank / Default

I made the one change you suggested (disable realtime priority thread) and I still have the problem.

I also tried changing the Y scan displacement from 0 to 1 or -1, and that doesn't fix it either!

I found another mention of fields being swapped:

http://www.gossamer-threads.com/lists/mythtv/users/214506#214506

I e-mailed him. Hopefully he's made some progress.

Leif

I have a theory!

OK, so apparently MPEG data can have a top_field_first flag. I found a place in MythTV where this is handled by the BOB filter, but I can't find a place outside the BOB filter where this is handled (not completely sure tho).

Since my display works fine at 1920x540p w/ BOB, and not well without it, my bet is that my local station is sending MPEG data that has the top_field_first flag different from what my video card is doing in the interlaced mode.

This would explain why it doesn't happen to many people. You'd have to be in an area where the TV station sends MPEG this way.

I spent about half an hour trying to get ffmpeg to print the value of this field for my shows, but I'm giving up for now.

Mythtv 0.20 advertises a feature where it automatically detects if a video required deinterlacing. While this won't solve the 1080i problem you described, it would allow you to always use 540p mode without having to manually toggle the deinterlace mode. There are postings that describe how to migrate R5D1 to 0.20.

Marc

I've noticed a few people complaining that the detection in 0.20 isn't very good, and XvMC has issues also, so I think I'll skip it for now. And it would be nice to get this working w/ a real 1080i modeline, so I could have the full spatial resolution.

I ran my test, getting ffmpeg to tell me what the top_field_first flag was. It's always 1 for my recordings. I have been *completely* unable to figure out what my video card is supposed to be doing w/ an interlaced mode. I guess back in the day when interlaced modes were common, computers displayed static images and nobody cared.

I also read the code for the "Overscan" page and found out why changing the value to -1 or 1 did nothing. If you don't stretch or shrink the display by setting the first two entries to something, it ignores the last two entries. I'm tempted to compile my own 0.19-fixes without this restriction so I can try to move the video down 1 line and see if that fixes it for all my recordings.

[quote="volfy"]
I ran my test, getting ffmpeg to tell me what the top_field_first flag was. It's always 1 for my recordings.
[/quote]
Oops, nevermind. Actually I have recordings that have top_field_first=0, and they play wrong too. So my theory that the problem is MythTV somehow not honoring that flag when not running BOB is wrong.

Back to square one.

[quote="volfy"]I have been *completely* unable to figure out what my video card is supposed to be doing w/ an interlaced mode.[/quote]

I've been following this thread and I think this is the key to your problem, namely, making sure that your video card is outputting interlaced, that it's outputting the proper interlacing for your TV, and that playback of interlaced material is synched appropriately so the right fields are played at the right times.

Given that I think most people just run progressive and let BOB handle deinterlacing. It's easier and the results are pretty smooth.