OSSC Sync issues specific to AV1

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  • #39819
    QXC
    Participant

    I’ve had some issues getting my OSSC to grab sync using the AV1 (Scart) port. I’m running RGB out of a PS1 or PS2 console, passing through a CRT via BNC ports, and then using BNC to SCART into the OSSC. When using the PS2, I can set the console’s output to YPbPr and it will grab sync as per normal (after changing to YPbPr input obviously). It also syncs to YPbPr when hooked up to AV2 or AV3 with the OSSC set accordingly.

    I also have a BNC to VGA cable, so I hooked everything up and the PS2 works as expected when set to YPbPr or RGBS, again with the OSSC set to the correct input signal. The PS1 also works. I noticed both displayed some jailbars, the exact number/pattern changing depending on the input signal (240p,480i,525i, etc). I believe this might be an issue specific to my VGA cable as I recall something similar happening with my USB3HDCAP, whenever it actually worked. I don’t know if this is something the LPF would solve? Obviously LPF does not work on AV3.

    Before I tried the BNC to VGA cable I thought that my playstation cable might have been the issue, since it’s one of the (discontinued?) retro access 1000uf cables. Given that it’s worked perfectly fine on my CRT and that it works via AV3, I don’t believe it’s an issue. I don’t believe it’s got anything to do with the jailbars, either.

    I continuity tested the BNC to SCART cable and sync/sync ground tested good on pins 19 and 17, as expected. So as far as I can tell that cable is also working as intended.

    I also wasn’t getting audio when using SCART/AVI in YPbPr mode. I tried the audio switch both ways, and confirmed that audio was being received via HDMI when using the 3.5mm inputs on AV1 as well as for AV3. I’ve updated to 086 firmware, specifically the “AUD” firmware for audio.

    Not really sure where to go from here, if I’m not missing something obvious with the OSSC settings it might be time to check the soldering on the OSSC perhaps? Everything looked perfectly fine when trying to glance in from under the covers.

    #39823
    nmalinoski
    Participant

    Is your CRT boosting sync to TTL on the loop-out? That might cause problems/damage on AV1 of the OSSC.

    #39825
    QXC
    Participant

    That I do not know, but for what it’s worth bypassing the CRT (PS cable BNC>BNC Scart) made no difference. It’s a late model PVM with an add in card, didn’t have any issues using the output with my USB3HDCAP (Again, when it worked) or feeding that output into other CRTs. Based on that, I THINK it’s 75 ohm.

    Other oddities I’ve encountered unrelated to AV1:

    – Everything I’ve thrown at it from the PS1 or PS2 shows up as 525i/263p, despite both consoles being NTSC. I’ve tried multiple units of both consoles. The output from the OSSC appears to be 60hz, so this on it’s own isn’t an issue. PAL games also show up as 525i/263p, for what it’s worth.

    – The aspect ratio seems to change depending on the input resolution and rescale, particularly with interlaced inputs. Most of the time the image is about half way between 4:3 and 16:9. Behavior is the same between my cheapo HDMI capture card and an actual HDMI input into a computer monitor. Some of these settings also whack up the framerate on the capture card but I don’t recall seeing the issues on the monitor (albeit more focused on aspect ratio). The no line doubling option seems to be correct most of the time. I’ll have to go back and write down exactly which scale on which input had what output ratio, but 0 scaling worked correctly all of the time IIRC. EDIT: Looks like this can be helped with tweaking.

    – Interlaced content doesn’t deinterlace amazingly, primarily menus having the occasional flicker/shimmer, but I’m fairly sure this is a setting issue that I just haven’t taken the time to look into. All of the timings stuff I keep hearing about.

    • This reply was modified 2 months, 2 weeks ago by QXC.
    #39840
    BuckoA51
    Keymaster

    Everything I’ve thrown at it from the PS1 or PS2 shows up as 525i/263p

    That’s correct, OSSC LCD shows the entire signal including non-visible parts, though PAL signal should be different.

    Interlaced content doesn’t deinterlace amazingly,

    OSSC is a line doubler, it doesn’t have a frame buffer so cannot perform sophisticated deinterlacing.

    #39908
    QXC
    Participant

    Not sure how to describe the “deinterlacing”, pretty sure deinterlace was off in OBS but something was having trouble with static lines (i.e. menus). It wasn’t a steady flicker, it’d just wiggle a bit every now and then. Possibly related to noise on my BNC>VGA cable. Still haven’t been able to poke at the settings for that yet.

    I’ve also had issues with the OSSC not sending out a signal when I first start it? Usually happens when the console is turned on before the OSSC. I’ll get the test pattern on OSSC startup and it will say it’s synced to a signal, but I get a black screen (capture card)/no output (monitor, goes into standby). This is usually solved with unplugging/replugging the A/V cable or restarting the console and then changing the scaling options around. Going to pick up a HDMI splitter so I can monitor the OSSC output easily and completely remove the capture card from the equation.

    In addition to that, sometimes the OSSC will drop sync during 240p/480i resolution changes. Typically the screen will rapidly switch between saying 260p and 525i, and this is resolved by changing the scaling settings. Sometimes the scaling options (typically 1x and 3x?) will do this when you set to them. Sometimes not.

    Again I still need to sit down and figure out the exact behavior, but generally speaking this seems to be a bit more finicky than I was expecting. I do wonder how many of these issues are cable related, and not being able to use my SCART cable isn’t helping. Sounds like I might just have to contact support about that.

    #40005
    QXC
    Participant

    Update, I’ve resolved most of the issues today. tl;dr user error 🙂

    – Issues on AV1
    I was not aware that scart has input and output on some lines (Or, I was but it didn’t register that this could lead to them being wired backwards), and my cable was wired for “SCART>BNC” Rather than “BNC>SCART”. This resolved the issues using RBGS as well as the lack of audio. I should have caught this while pin testing the cable. The seller did mention this in their listing, and offered to fix it for the cost of shipping, but I’m impatient so I had my much more soldering competent roomate switch them around real quick.

    – Jailbars
    So far not present with AV1 with my limited testing, so I’m now fairly confident that it’s an issue specific to the VGA>BNC cable I was using. I had also found some interference that manifested in moving horizontal lines on the screen, also gone now that I’m using the higher quality SCART cable. I want to mess around with the LPF just to make sure but I’m 99% sure this was entirely a cable issue.

    – Aspect ratios
    Still need to investigate this, but I’ve gotten my capture card to accept the correct aspect ratio so that’s not a huge deal. Very likely this is a setting I haven’t messed with yet.

    – Interlacing/deinterlacing
    The behavior I was seeing is isolated to the capture card not being able to process the interlaced signal particularly well. Using an HDMI splitter I see the same signal on my monitor with a steady flicker as expected, whereas the capture card creates a kinda inconsistent wiggle. I’m using a bargin basement capture card so this isn’t a surprise, just wanted to confirm what was going on.

    – Picture dropping on input signal change/signal not being sent on startup
    I need to test this more but I managed to get the capture card to drop picture once or twice today while the monitor was still showing output. Both devices hooked up to the OSSC via HDMI splitter. So this seems to be some issue related to the capture card specifically.

    – Sync dropping on OSSC on input signal change
    This hasn’t been well tested yet but I’m fairly confident that it’s an issue cased by interference on the VGA>BNC adapter. It happened on a somewhat regular basis with that cable, albeit inconsistently, so an evening of PS1 games should determine if that’s still happening or not.

    Needed to hit up support to realize I had the wrong scart cable, so I can’t take credit for figuring that one out. But now everything is working more or less as expected. I’ll post another update once I’ve figured out the rest of the problems. Never know when your forum posts will turn up in a search result 7 years later.

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