Confused about how OSSC works with PS2

NewHome Forums OSSC, OSSC Pro and DExx-vd isl OSSC – Discussion and support Confused about how OSSC works with PS2

Viewing 8 posts - 1 through 8 (of 8 total)
  • Author
    Posts
  • #43817
    Res1s7
    Participant

    Just got one of these and the default video quality is compelling compared to the usual abysmal HDTV scaling.

    However I’m confused about how this device works with the PS2. Most guides seemed to be orientated towards 240p. What video type/resolution should I be getting with the PS2 ? Should I be able to get my monitor to scale the top and and bottom edges of 4:3 to full the panel dimensions ( https://www.viewsonicglobal.com/public/products_download/user_guide/display/vx2457_mhd/english.pdf?pass ) ? I tried “overscan” but it just stretches a bit to the left and right. The PS2 output from OSSC is still basically a box in the middle of screen but big enough if I can’t enlarge it somehow. At first I tried the OSSC on my old Bush HDTV (a 1080p Bush Flatscreen TV DLED32165HDDVD) and all the line doubling modes worked apart from 5x but that didn’t surprise me. So I tried it on the Viewsonic next but 5x still does not work and the OSSC again says “not supported”. However I’m not sure if that means not supported by the Viewsonic or that the OSSC can’t support the output of the PS2 for 5x mode.

    My next task tomorrow is to try the suggestions on this thread).

    So a bit confused here so any clarifications appreciated ! But so far the output is impressive even with default modes. I’m going to look forward to eventually fine tuning it. I already noticed in Medal of Honor: European Assault that the HUD white text has a slightly greyer off set “drop shadow” if I look closely which is not visible on screenshots and videos on the web.

    #43824
    Harrumph
    Participant

    The PS2 mainly outputs in 480i (or 576i in PAL), this will be shown as 525i or 625i on the OSSC info LCD (the full line count). Interlaced signal is not the strong point of OSSC, unfortunately. There is no x5 mode for interlaced.
    How it will look is largely up to your display scaling. But not filling the screen is common anyway, because many games don’t use the full vertical resolution.

    #43837
    BuckoA51
    Keymaster

    Many people prefer to use pass through mode for PS2 games on their PS2, and save the OSSC for scaling/line multiplying PS1 games.

    Certainly with a set like an LG C9/CX, game mode deinterlacing on the TV itself is pretty decent.

    #43848
    Res1s7
    Participant

    OK thanks Harrumph and BuckoA51. At first I thought I was just being a bit thick with everything to do with the OSSC, but now I’m beginning to understand the concepts I can see that what I was getting into was a Jujitsu master class and crash course in video processing all rolled into one ! Maybe VGP should give out some kind certificate ?

    So far …

    1. The reason that I have a box within a box on my display is that the larger box represents the full extent of the CRT display that the PS2 is expecting to find. The gap between this full box and the smaller actual display of the game is where the edges of the curved parts of the actual CRT tube would have been. Is this called “overscan” or is that something else ?

    2. Having grasped that this device is actually well established way of doing this I beginning to understand that I can alter the timing to adjust the final image geometry. I already shifted the image left/right using the horizontal timing adjustment in the OSSC menu. What I don’t understand is if I can enlarge or shrink the final display using some of these timing settings. Is this possible ?

    3. Scanlines. Someone suggested that you can use the OSSC post-process scan lines to mask the flicker effect of the “bob” interlacing … “I have the OSSC black out the repeating lines from 480i games. So essentially no more annoying bob deinterlacing flickering while still getting the benefit of no added lag.” ( source ). I tried that but could not reduce or remove flicker. Am I barking up the right tree here ?

    So I’m slowly getting used to the OSSC with the PS2. I takes a bit of getting used to as its as if an actual CRT display is my HDTV !

    #43875
    Harrumph
    Participant

    1. Yes that is pretty much correct. Example SNES (ntsc) has 262 lines total, 22 of those are blanking period, 240 is active video. However, the system can never display more than 224 lines of actual video (not strictly true actually, but for the sake of this argument). So it has 240-224 = 16 lines that would be expected to fall outside of the visible edge anyway. In general the term overscan refers to the behavior of the crt TV display, not the source. All TVs at the time had 5-10% overscan, for reasons not necessary to go through here. There are articles on wikipedia etc.

    2. You can change the ”active” area. Those are the V.Active and H.Active settings. Adjusting them may cause non-standard output timings, so some displays will not accept them. If they do accept them, it can be used as a sort of zoom. E.g. many games/systems only have actual video on 224 of 240 lines (like I mentioned above), or 448 of 480 lines (480i games). So if you lower v.active from 240/480 to 224/448, on those games/systems the image will then go to the edge of your screen. But this is dependent also how your display does scaling. Remember to compensate with backporch if you alter the active value.

    3. You need to set ”alternating” scanlines and at 100% strength for this approach to work. Some people find it emulates the look of interlace on crt pretty well, others don’t.

    #43886
    Res1s7
    Participant

    OK, thanks for the explanations. I did eventually find what I was really looking for which is this post

    Speaking purely as a guy who cleans and converts VHS to digital for a living, I’d personally just use the passthrough mode with the majority of PS2 games. The reason the 2X, 3X and 4X modes look so good on Sega Mega Drive, SNES and N64 is because the majority of the games output at 240p or 288p. Because the signals are progressive, that means the OSSC has all the lines that make up the frame right from the word go. The PS2 on the other hand primarily outputs at 480i or 576i – interlaced video signals. What that means is the console alternates between showing the odd and even numbered lines that make up the frame separately. In progressive video, 30 frames per second is just that. But in interlaced, 30 frames per second is actually 60 half-frames per second. Not half as in chopped in half, but half the lines that make up the frame. That means with 480i or 576i content, at any given time the OSSC only has half the image to work with. Linedoubling such content means half the vertical resolution is lost.

    For that reason, I would NEVER linedouble an interlaced signal unless it was a re-release of an old 288p game that was converted to 576i. The PS2 has a few games like that, such as the Sonic the Hedgehog collections. Deinterlacing such games in the normal field combination method generally results in combing artifacts where there shouldn’t be any, whereas linedoubling 288p games that were converted to 576i surprisingly retains the original visual intention. But for the vast majority of games that were rendered at 576i to begin with, you’re better off letting your TV or some other device do the deinterlacing. Even a cheap scaler will produce a more accurate deinterlace of such content than the OSSC or RetroTINK.

    I have found the OSSC to be very confusing (but interesting). By the sound of it I am not alone …

    “Also, most users are not trained in video production; this often causes poor results as many people do not know much about deinterlacing and are unaware that the frame rate is half the field rate.” – Wikipedia Page on Deinterlacing.

    This is also what I failed to appreciate on the product page

    “The OSSCs deinterlacer is lag free! Note that this does however mean there’s a drop in picture quality for interlace sources, but this is unavoidable.”

    So, unless I keep it for the 240p games, do I basically have a glorified pass through (but the scanlines are cool) for my PS2 ? Are there better alternative products for PAL 576i and NTSC 480i PS2 gaming that will deinterlace and upscale things better than my TV will do without losing drop shadows and sprite effects ? I already know about the Framemeister but that is discontinued and very expensive on ebay (I was seeing them going for $750).

    #43898
    Harrumph
    Participant

    I don’t agree with the bolded sentence in the quoted text. It cannot be claimed that resolution is lost when no lines from the source has been removed, and the temporal resolution likewise has not been altered. On the other hand, is bob-deinterlacing ideal? Obviously not.

    If your main use will be interlaced content from PS2, then yes there are better alternatives. You can check out the GBS-Control, which seems pretty darn good for interlaced (and 240/288p as well actually), which is available right now (and quite cheap to boot). Or wait for sometime next year, when OSSC Pro will be available.

    #43908
    Res1s7
    Participant

    I don’t agree with the bolded sentence in the quoted text. It cannot be claimed that resolution is lost when no lines from the source has been removed, and the temporal resolution likewise has not been altered.

    Right, LOL. I don’t think I’ve ever bought a piece of technology with so many myths and misunderstandings around it.

    So the error in his statement is that the OSSC is doubling each line of EACH FIELD (not a just a single field). So the two fields are still combined into the progressive output with no loss of any lines or quality loss, apart from ….

    “The rule of thumb is, if your priority is a good picture, use your displays deinterlacer.” The OSSC Quick Start Guide.

    So that refers to the slightly flickering image due to bob de-interlacing as well as some combing artefacts. If this is correct I can more than live with this.

    EDIT: But my explanation is not quite there, and also (is it just me) why can no one seem to quite accurately explain what’s going on ?

    (Me after days with the OSSC lol … could not get the forum to display this image.

    Anyway I found the following that explains it much more adequately for me …

    “Bobbing: each field gets a full frame.. instantly, you have twice the amount of data/file size and you have to double the speed of playback.. otherwise, your video gets slowmo.. smooth movement, but some content could ‘shake vertically’.” – Source.

    “Each field gets a full frame”. FINALLY ! That’s all I wanted to know.

    As a final question, and BTW thanks for sticking with me on this, is there anyway in the OSSC to “dump” or “screenshot” what the OSSC is sending to my TV so I could make direct pixel by pixel comparisons between output modes ? I could just photograph the TV screen but this is already like comparing differences between audio sources, its subject to placebo effects.

    EDIT 2/ADDITION: So I had to add this as well

      as I finally cracked it

    . I originally tried GSM ( Graphics Synthesizer Mode Selector ) but decided it just did not work with enough games. However after reading that Component output is required for 576p and other progressive output I tried switching to component output in the PS2 menu (not RGB) to see if I could send that down my SCART cable into the OSSC. It worked !. So then I try GSM again with a game that is not listed as supporting any progressive output; Medal of Honor: European Assault. 576p now works with it. However it was still badly scaled on my TV. So I tried 480p and that scales better. All the other GSM modes lead to blank screens or crashes. So now I have much better scaling AND progressive video input to the OSSC. For some reason I can only get 2x doubling and passthru options available for both 480p and 576p. I also altered some of the timings to properly scale the resulting game video but its still cropped off the bottom but playable. Does anyone know anything else I can try to center the image properly ? See this screenshot that shows the OSSC timing settings in the menu. It scales to the top properly but what you can’t see in the photo is cropping off the bottom of the frame which just crops the bottom of the HUD in this game. Cheers.

Viewing 8 posts - 1 through 8 (of 8 total)
  • You must be logged in to reply to this topic.