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TV or not TV, that is the question.... — Parallax Forums

TV or not TV, that is the question....

ColeyColey Posts: 1,112
edited 2011-05-16 11:45 in Propeller 1
I am currently working on a new project with Baggers, a new game console / retro computer.
One of the things I am unsure of is how many of you actually use the TV output?
Do you use TV output because you need more colour depth and are not so bothered about resolution?
Do you prefer VGA output because that is what you have on your desk?

To add a decent TV (PAL & NTSC) output with 8 bit colour adds quite a bit of extra cost and PCB real estate so I need to know if you had VGA low resolution 320x200 at 256 colours would you even want a TV output?

Your help is appreciated.....

Regards,

Coley

Comments

  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2011-05-01 13:48
    Both

    OBC
  • MagIO2MagIO2 Posts: 2,243
    edited 2011-05-01 13:50
    Easy, isn't it?

    RETRO = TV

    I think the blurry TV out fits much better than a sharp but low-res VGA.
  • ColeyColey Posts: 1,112
    edited 2011-05-01 14:01
    @MagIO2

    I think you are right for the lower resolutions but what about higher ones, we won't be limiting it to 320x200 just that other modes will be tilemapped.....
  • MagIO2MagIO2 Posts: 2,243
    edited 2011-05-01 14:18
    What about making this part a module? The "mainboard" neither has VGA nor TV but pins reserved for that purpose. One can then buy his preferred module - or maybe both.
  • localrogerlocalroger Posts: 3,452
    edited 2011-05-01 14:23
    In propellerland the standard TV output is 3 resistors and 3 pins and the standard VGA output is 8 resistors and 8 pins, so I'm not sure where you get the "decent TV output taking PCB real estate." The standard designed in Prop TV output is what it is; it's easier to design a flexible driver with lots of color options because the scan rate is slower than VGA and you can run more code to build the next WAITVID. For anything but the coarsest VGA you will probably need 2 or more cogs for the driver.

    On the other hand the bandwidth limit of a TV signal causes certain color combinations to smear badly, and the whole thing looks rather fuzzy at best compared to VGA which can display a nice sharp image with any color combination at any resolution as long as the driver can get the pixel data to the WAITVID instruction on time.

    It is very easy to find cheap TV monitors of any size. Small VGA monitors tend to be quite expensive because they are a niche market. On the other hand most newer full-size TV's are equipped with VGA and digital inputs and those look great, whereas TV looks very fuzzy on a big flatscreen.

    If you are trying for any kind of performance at all the drivers for TV and VGA are likely to have different fundamental capabilities re: resolution, tile capabilities, and especially color output, so creating any application that will work with both is difficult to impossible. If you take OBC's suggestion it's likely you will have applications that work on one but not the other or that have two different versions custom written for the different video options.
  • ColeyColey Posts: 1,112
    edited 2011-05-01 14:33
    localroger wrote: »
    In propellerland the standard TV output is 3 resistors and 3 pins and the standard VGA output is 8 resistors and 8 pins, so I'm not sure where you get the "decent TV output taking PCB real estate." The standard designed in Prop TV output is what it is; it's easier to design a flexible driver with lots of color options because the scan rate is slower than VGA and you can run more code to build the next WAITVID. For anything but the coarsest VGA you will probably need 2 or more cogs for the driver.

    On the other hand the bandwidth limit of a TV signal causes certain color combinations to smear badly, and the whole thing looks rather fuzzy at best compared to VGA which can display a nice sharp image with any color combination at any resolution as long as the driver can get the pixel data to the WAITVID instruction on time.

    It is very easy to find cheap TV monitors of any size. Small VGA monitors tend to be quite expensive because they are a niche market. On the other hand most newer full-size TV's are equipped with VGA and digital inputs and those look great, whereas TV looks very fuzzy on a big flatscreen.

    If you are trying for any kind of performance at all the drivers for TV and VGA are likely to have different fundamental capabilities re: resolution, tile capabilities, and especially color output, so creating any application that will work with both is difficult to impossible. If you take OBC's suggestion it's likely you will have applications that work on one but not the other or that have two different versions custom written for the different video options.

    This will not be using standard DACs, they are custom to give 256 colours and to give a composite output they need a TV encoder like AD723.
    Your comment about newer TV's having VGA inputs rings true, we have four televisions in our house and three of them have VGA inputs, that's really what prompted my question.
  • ColeyColey Posts: 1,112
    edited 2011-05-01 14:36
    MagIO2 wrote: »
    What about making this part a module? The "mainboard" neither has VGA nor TV but pins reserved for that purpose. One can then buy his preferred module - or maybe both.

    Have you been sneaking a peek at my designs as that is exactly what I am doing lol

    I may do two different video board versions but again cost will be an issue, TV will be more expensive than VGA for example......

    There won't be any point in making it if the price is out of reach....
  • localrogerlocalroger Posts: 3,452
    edited 2011-05-01 14:36
    In that case I would not bother with the TV output. It will look like Smile and still probably still have incompatible resolution and color depth compared to the VGA which you know you'll want. What I would suggest, since a lot of people will be using it with their TV set which is across the room, is you might want to consider making the user interface IR remote instead of hard wired (or use common wires like RJ11 or RJ45 for which cheap extensions are available) so they can put the prop console under the TV set and operate it from the sofa.

    Editing to elaborate: I think this is a particularly good approach since while most new TV's have VGA inputs, very few people use them since they're using either TV or HDMI. So the VGA jack will be available without yet another switch or a bunch of cable switching.
  • ColeyColey Posts: 1,112
    edited 2011-05-01 14:45
    localroger wrote: »
    In that case I would not bother with the TV output. It will look like Smile and still probably still have incompatible resolution and color depth compared to the VGA which you know you'll want. What I would suggest, since a lot of people will be using it with their TV set which is across the room, is you might want to consider making the user interface IR remote instead of hard wired (or use common wires like RJ11 or RJ45 for which cheap extensions are available) so they can put the prop console under the TV set and operate it from the sofa.

    Editing to elaborate: I think this is a particularly good approach since while most new TV's have VGA inputs, very few people use them since they're using either TV or HDMI. So the VGA jack will be available without yet another switch or a bunch of cable switching.

    Yes I think you are right, composite signals on newer televisions look awful and we will have a remote wireless option for the interface control.
  • RoadsterRoadster Posts: 209
    edited 2011-05-01 15:40
    I prefer tv, but I guess it would be good to have both
  • ericballericball Posts: 774
    edited 2011-05-01 18:36
    Coley wrote: »
    I am currently working on a new project with Baggers, a new game console / retro computer.

    320x200 is a little beyond artifact-free composite TV. And if you're doing a retro-computer, you're going to want to go up to 640x480 for text modes.

    One other advantage of VGA is you won't have to support both NTSC and PAL.

    However, the advantage of TV is everyone has one.
  • TubularTubular Posts: 4,717
    edited 2011-05-01 19:49
    Coley,

    How about designing for a 15 pin VGA output including power. Then design a small plug in board "Retro Extender PAL/NTSC" with 15 pin male VGA and the AD723 on it?

    That plug in board could be useful with all sorts of other prop designs that put out VGA, but not 256 colour TV at the moment.

    You could use the I2C pins on the VGA output connector to sense when VGA, PAL or NTSC is being used, either using a small eeprom (use existing prop I2C pins) or some other kind of sensing.

    I suspect you might be able to squeeze the adapter into a 9 pin backshell S-video or RCA coming out where the cable normally does
  • davidsaundersdavidsaunders Posts: 1,559
    edited 2011-05-01 21:31
    However, the advantage of TV is everyone has one.
    I do not. and many do not.
  • potatoheadpotatohead Posts: 10,261
    edited 2011-05-01 22:47
    Deffo TV output with the DAC. Agreed with Eric above.

    TV has the lower sweeps. With the nice output chip, the props can run at the max, and there will be both the drivers shipped with it, and others over time. TV has the most potential for tossing stuff around, IMHO.
  • Cluso99Cluso99 Posts: 18,069
    edited 2011-05-01 23:13
    I have been through the same dilemas. VGAs are cheap as chips (almost). Any council cleanup will result in some old style VGA tube monitors if you don't already have them.

    Then again, most TVs (LCDs and Plasma) have composite video input these days, and some have lots. Some have VGA although I note HDMI is becoming the norm here.

    Answer: I don't know so I am providing either/or but no DAC, so it is an easier answer. BTW I have just recd a 4.3" TFT LCD composite car monitor for ~$25 from eBay so I am interested in its quality.

    I am now using a 6x1pin 0.1" header for VGA because I do not have enough room for a VGA connector, nor the support required for the cable (my boards are smaller than the VGA plug). If you go the 6pin route I have header shells and pins (had to buy 1K & 10K respectively). Looking at pcb edge from outside, left to right, GND, VS, HS, B, G, R (made the most sense since this is the order of the pins on the VGA socket).
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2011-05-02 01:57
    Due to old age all of my remaining glass "TV" monitors are only kept out of the skip by nostalga. The LCD ones that I have are really just VGA ones to start with.

    C(E)GA was very close to NTSC, wasn't it?
  • ColeyColey Posts: 1,112
    edited 2011-05-02 02:17
    Tubular wrote: »
    Coley,

    How about designing for a 15 pin VGA output including power. Then design a small plug in board "Retro Extender PAL/NTSC" with 15 pin male VGA and the AD723 on it?

    That plug in board could be useful with all sorts of other prop designs that put out VGA, but not 256 colour TV at the moment.

    You could use the I2C pins on the VGA output connector to sense when VGA, PAL or NTSC is being used, either using a small eeprom (use existing prop I2C pins) or some other kind of sensing.

    I suspect you might be able to squeeze the adapter into a 9 pin backshell S-video or RCA coming out where the cable normally does

    Thats a good idea and I will look into it, I was looking at driving the AD723 clock and PAL/NTSC switch directly from the gfx cpu, its what I did for the first PropGFX and the output was superb. That would make it tricky to add as an addon but worth further investigation....
  • BaggersBaggers Posts: 3,019
    edited 2011-05-02 06:49
    Separate add on would be a good idea, that way PAL could have a cheap Scart option too :D
  • JT CookJT Cook Posts: 487
    edited 2011-05-03 07:31
    I am curious to hear more about this retro computer/console!
  • ColeyColey Posts: 1,112
    edited 2011-05-03 08:41
    JT Cook wrote: »
    I am curious to hear more about this retro computer/console!

    I bet you are, but my lips will remain sealed until I have something more substantial to show.
    I will say one thing though, it uses more than one propeller......:cool:

    Regards,

    Coley
  • ColeyColey Posts: 1,112
    edited 2011-05-03 08:43
    Baggers wrote: »
    Separate add on would be a good idea, that way PAL could have a cheap Scart option too :D

    I might have a solution, have ordered a real cheap (less than $10) converter off ebay, will see how that goes and report back

    Coley
  • TubularTubular Posts: 4,717
    edited 2011-05-03 13:59
    They look like a really good option if they work. Wonder whats inside? Some are so cheap there may be nothing inside with the signalling being done by the video card?
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2011-05-03 15:07
    It was the RGB to PAL thing that led me to the Prop, away from the likes of ChipBasic2. I was then working at a service centre that I could ge access to some Sony chips, to transform the RGB to domestics. Then i found that there was a self encoding chip (Prop) and so the FBAS Xilinx thing wasn't needed (although the workings of it are a source of fascination).

    With all of this I still didn't have a PAL/NTSC monitor with a decent focusing tube, so a form of (xyz)GA was needed. That was the sealer for the Prop's case. Then all you good folks came along with a viable Nascom into a VGA which gave me better focused resolution than I had back 30 years ago.

    I look forwards to the desciptions of that "cheap SCART". It might be just not good enough to give the same effects as the modified Phillips B&W ....(1978/9)

    Alan
  • TubularTubular Posts: 4,717
    edited 2011-05-12 15:38
    Coley

    How did you go with the cheap converter option?

    I also ordered one off ebay... but it was $1.25, and guess what it's hardwired with zero smarts. The RCA composite video jack is wired to pin 1 of the D15 and the S-video connector to pins 2 and 3.

    Any smarts must be done with the video card doing the driving.

    I guess I'm not really surprised by this given the price. Did you have any better luck?
  • ColeyColey Posts: 1,112
    edited 2011-05-13 11:51
    No, not received them yet, probably stuck in customs.....

    Will post as soon as I get them :smile:

    Coley
  • ColeyColey Posts: 1,112
    edited 2011-05-14 04:14
    Look like I have found a good solution here :smile:

    I got this VGA to Video converter off ebay here

    It has VGA In and VGA Pasthru, Composite Video and S-Video Outputs PAL/NTSC Switchable.
    It also has a little menu system built in to alter video size, brightness etc.....

    attachment.php?attachmentid=81186&d=1305371247attachment.php?attachmentid=81183&d=1305371240

    This is standard Parallax VGA Text Demo running on Demoboard converted to PAL Composite Video.
    attachment.php?attachmentid=81185&d=1305371246

    And here is a closeup
    attachment.php?attachmentid=81184&d=1305371244

    I have to say for the money this little box of tricks is awesome and I certainly couldn't add PAL/NTSC to my new board for less than this cost.......

    Enjoy!


    Coley


    VGA to Composite.jpg
    PCB.jpg
    VGA on TV.jpg
    VGA on TV Closeup.jpg
    PCB.jpg
    640 x 480 - 161K
    VGA on TV Closeup.jpg
    640 x 480 - 125K
    VGA on TV.jpg
    640 x 480 - 119K
    VGA to Composite.jpg
    640 x 480 - 110K
  • prof_brainoprof_braino Posts: 4,313
    edited 2011-05-14 07:24
    Coley wrote: »
    I have to say for the money this little box of tricks is awesome and I certainly couldn't add PAL/NTSC to my new board for less than this cost.......

    Would it be resonable to leave the layout for TV connections on the board, unpopulated? Just a though. Seems newer TV's have an assortment of connectors, so the only case where tc is actually needed is when one wants to use an acient tube TV. If you are going 'really' retro, that would be the target. But I figure anybody when this as a goal would also be motivated to get a soldering iron and add the parts. And write the code? Maybe it not a reasonable scenario. Anyway, just a thought.
  • TubularTubular Posts: 4,717
    edited 2011-05-16 06:30
    Coley

    Thanks an awesome box for the price. I have a similar one from Jaycar maybe 5 years ago, it was more like $60, and doesn't have the on screen menu. Wow.

    Its big though, so I still think its worth trying an AD725 in a backshell, I'll give it a whirl. Did you really think the prop could clock the AD725? I would have thought too much jitter? I might put pads down for an xtal just in case.
  • ColeyColey Posts: 1,112
    edited 2011-05-16 11:45
    Yeah I guess it is a little large but then I tucked it behind my TV so don't even know that it's there.
    This thing is pretty awesome it will do up to 1280x1024 though I doubt that would look very nice on NTSC or PAL for that matter lol

    As for Prop driving the AD725 clock, it will work, we have tested it with original full fat PropGFX and that's also how Uzebox AV core does it too albeit with an AVR......

    Regards,

    Coley
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