Keeping everything interlaced - will it work?

[something fishy]

I have a Radeon 9600 driving the (PAL) TV directly at 720*576@50i via a VGA to scart adapter (as described here:
http://www.idiots.org.uk/vga_rgb_scart/
and here:
http://ryoandr.free.fr/english.html).
My understanding from here:
http://www.cask-of-amontillado.com/p...rlacing,_overs
is that I can turn off deinterlacing in the software MPEG decoder and output a native interlaced signal avoiding the softness produced by the interlaced -> progressive -> interlaced chain and hopefully match the picture quality of the PVR350/xCard (I have both but I want to play DVDs off my media server).

I’ve tried it but at the default Sage settings the scan lines don’t match (using VMR9) resulting in severe combing. Has anyone got this arrangement to work? I’ve noticed that Sage is scaling the video image 105% both horizontally and vertically. This is presumably a software overscan control but must also throw the scan lines out of whack. Is it just a matter of changing this to 100% in the aspect ratio setup control and adjusting the videocard timing to create the correct amount of overscan?

Also, which in most peoples’ experience is the most stable software MPEG decoder in Sage. I’ve had an unworkable number of lock ups with nVDVD 4 (doesn’t seem to like playing multiple files). Are the intervideo decoders stable?

Thanks
Eric

[nielm]

It should work -- I am about to try this, once I get all the parts, and will be very interested in hearing about the results!

The scaling is done by sage -- in the detailed setup you can change the scaling factors for each aspect ratio (multimedia section I think), you can probably also edit it in the .properties file [edit-must read better, you already mentioned this]. If you set it to 100%, and your desktop res is *x576 you should be OK.

'turn off deinterlacing' does not really mean anything, as there are always 2 separate half-frames (field) in the MPEG stream that have to be combined somehow... 'Weave' deinterlacing just interlaces the 2 fields into a single frame...
Because you are getting combing, I guess this is what you have set

Re decoders:
The intervideo decoders that come with the PVR boards cannot play back real DVDs (no CSS decryption), but are probably ok (ahem) with DVDs on hard disk...
The Sage MPEG decoders that come with V2.2 cannot play back DVD audio (no AC3 support).

I have been very happy with PowerDVD XPv4 up to now, but I believe that it prefers overlay (which I have always used up to now!) to VMR9.

[willemse]

I use a FX 5200 and has come trough extensive tests done to the conclusion that Interlace gives me the best picture. The connection to SDTV is via S-Video. TV monitor set as primairy. Quality is close if not same to regulair TV output.
Set up in Sage: Overlay, scaling is done in sage -- in the detailed setup you can change the scaling factors for each aspect ratio and i use 100% (some % above 100% give stuttering!) NVidia DVD decoder 100.67

It seems to me as that the proces done to convert to progressive output causes quality impact to a for me at least unacceptable level on the VGA monitor.

Nielm,

If I recall correctly are you using a FX5200?
I am very much interested in your results.

[Wheemer]

willemse, I'm confused by your post...

Interlace gives me the best picture

Is this a typo or are you in fact running an interlaced output through the nvidia decoder?

[nielm]

willemse: My new set-top-box (actually an 'on-a-shelf-in-the- basement-under-the-TV-bloody-great-big-server' ) which I am in the process of building will have an FX5200... I will start with the Svideo TV-out and see how things go, but I will probably try out an VGA->RGB Scart interface at some point...

[willemse]

Originally Posted by Wheemer

willemse, I'm confused by your post...



Is this a typo or are you in fact running an interlaced output through the nvidia decoder?

Wheemer,
I am running:
- Overlay,
- MPEG2 Video Decoder filter: Default which = NVIDIA
- DXVA Deinterlacing Bob and Weave.
- NVIDIA Decoder properites set as in attached jpg
- FX5200: TV set as primairy monitor -> interlaced signal via S-Video -> SDTV

Hope this clarifies and confusion is gone!!

[nielm]

willemse, from what I understand the 'smart' deinterlace in Nvidia tries to auto-detect whether the original input is an interlaced (each half-frame (field) is actually shot at a different time), or progressive (no interlacing -- pre-recorded MPEGs such as DVD only), or even progressive film encoded onto interlaced video -- each frame is split into two interlaced fields.

It will then choose Video (bob) or Film (weave) deinterlacing depending on what it thinks it is seeing.

(note BOB means each 288 line half-frame (field) is expanded to full frame and displayed at double the frame rate (if possible) which ends up meaning that on TV-out you are only playing back half-frames).

So with video mode/BOB, you will get no deinterlacing artifacts, but you are only viewing half the resolution of what is recorded. I can see loss of clarity this when I play back on my monitor, not yet tried Svideo...

[nielm]

willemse:
from what I understand the 'smart' deinterlace in Nvidia auto-detects whether the original input is interlaced (each half-frame (field) is actually shot at a different time), or progressive (no interlacing -- pre-recorded MPEGs such as DVD only)...
All PVR-x50 recorded MPEGs are interlaced because broadcast TV is interlaced (HDTV excepted!).

Video mode deinterlacing methods are

• 'Display fields separatley' (BOB) (vertically stretch each 288 pixel field and display it a twice the frame rate)
• 'Combine fields' (Weave) (simply interleave 2 frames)
• 'Blend' -- hardware accellerated weave+smoothing (if available)
• 'adaptive' -- hardware accellerated combination of blend+weave depending on whether the pixels are moving or not (!) (if available).

Note that with BOB, even though the decoder is pumping out 100fps, only 50fps will be sent on the TV-out, which ends up meaning that you are only playing back half-frames...

On my 5200FX, I have only ever seen it use BOB... So with the settings you have, you will get no deinterlacing artifacts, but you are only viewing half the resolution of what is recorded. I can see this loss of clarity when I play back on my monitor (especially in text, such as scrolling tickers), not yet tried Svideo out...

[willemse]

Nielm,

Tks for your explanation and inputs to my settings. Will try and let you know of my findings by tomorrrow.

[something fishy]

In my case it doesn't work. Either the granularity of the aspect ratio adjustments isn't precise enough and/or the decoders are unstable but, whatever, I can't get a comb free picture (sometimes it starts off virtually comb free but goes out of sync over a few minutes).

I've tried vertical scaling of 99~105 using the VMR9 and 99~105 using the overlay (v4 of the deCSSed intervideo decoders in both cases). For the VMR9 the sweetspot seems to be either 100% or 101% vertical scale, for the overlay the sweet spot seems to be 103-104% vertical scale. In neither case is combing eliminated with any consistency.

However I am wondering if it really makes a difference given that I am outputting an interlaced signal to a SDTV. I have set the BOBWEAVE dword in the registry to 1. I presume sets it to bob mode and using the overlay I get completely clean and smooth text on scrolling tickers (my quick test) with no microstutters. If bob just replicates lines to convert an interlaced image to progressive I don’t see how I am really losing any resolution if a) I’m outputting an interlaced signal b) I’m not rescaling and the scan lines very nearly match up (I can see how it would lose resolution to a progressive display).

I’ve not done any critical tests to see if the picture is softer (it was getting late) but there was an absolute lack of artifacts and stutters with this set up that was appealing.

Now I have to hope that the Intervideo decoders are stable. At the moment I’m getting many more lockups than I was using a PVR350.

BTW I’m using the SageMC STV and Sage 2.2.5RC1 – should I be getting transparent menus with the Overlay; the VMR picture is neither as solid nor stutter free with these settings.

[something fishy]

@Nielm
Can you share your settings for PowerDVD XPv4 I have this installed to play DVDs (using two different Decoders lets me fine tune the settings for (mostly NTSC film based) DVDs and (mostly PAL) TV seperately. You're right it won't connect to the VMR but I get a blocky bright (lime green) hash instead of a picture using the PowerDVD decoder and the overlay.

It goes to a bright blue hash if I turn off Sage's "hardware decoding" switch.

Cheers

Eric

[nielm]

In PVD itself, right-click Configuration.
In the dialog, Video tab, I have
Hardware accelleration enabled
color profile Original
Advanced->Screen->Video Mode: Auto Select
(I believe that this gives Bob on interlaced video files and Weave on progressive DVDs).

In Sage I keep everything at default, apart from the video/audio renderer (Overlay) and decoder (Cyberlink).

[something fishy]

So far this is looking like a failure. I have tried WinDVD4 (CSS-free hauppauge edition), WinDVD5 (full install of WinDVD5 I had lying around), PowerDVD xp v4 and PowerDVD 6 and nVDVD4 (1.00.67) - all with hardware acceleration and interlacing on and off. None provide the sharpness, smooth stutter free playback and general feeling of solidity of the PVR350.

This is with my Radeon 9600 driving the TV directly at 720*576@50i. Using weave interlacing is a non starter - I just can't get the scan lines to match. Using bob/automatic still leaves artifacts on fast moving high contrast edges and no decoder was as smooth and microstutter free as the PVR350 (either with or without reclock).

I have a 6600GT in one of my office PCs; my last option is going to be trying the nVDVD decoders with that - I will have to use s-video rather than the vga to scart cable (no composite sync from nvidia cards) and I'm not optimistic but why not?

At the moment the best option seems to be using the PVR350 for timeshifting TV and a software decoder for DVDs (they're almost all NTSC film based). Does anyone know if Sage will send girder an event when it goes into and out of the video library menu (actually the My Videos menu as I'm using SageMCE stv) I'm too lazy to change channels on the TV).

Cheers
Eric