Recalbox on CRT TV (composite)


  • Moderator
    Team

    @tifsmo Please make sure your A/V cable respects :
    text alternatif



  • I tried to connect my raspberry model B to my old CRT a few weeks ago, and it didn't work.

    After googling a little bit I discovered that my cable wasn't compatible. Fortunately I had a 4 pin jack connector and after a few soldering I was able to fix the cable.

    It also didn't work, I googled again and I discovered that I have to configure the config.txt file. I couldn't because I was in my village house and I didn't have internet and a proper computer to do it.

    I've bought the following adapter in ebay to fix my old cable and have the proper pin connections:

    0_1509452120520_s-l1600.jpg

    The adapter is coming from China so it will nedd a few weeks to arrive.

    I thought that connecting the raspberry via 3.5 jack connection I will have a video image like the classics arcade. With the feedback from "tifsmo" I'm worried if it's worthy all this effort.



  • @substring

    i made sure. i knew that the pin layouts are often times different on most cables you get (for example video would be on the red respective rca connector instead of the conventional yellow one etc.). i tried three different cables in total and four different crt tvs. even opened up two of the cables and resoldered them to match the proper colours of the rca connectors.
    same deal on all of them. there were slight differences between the tvs, but the image was never good on any of them and audio was always distorted.

    it might just be that the trs port on my specific pi is broken or something but since then i read various reports online that the trs ports on any pi are basically s**t and you just can't get a good signal out of them.

    let me know if you have better luck @Genaker

    cheers
    tim


  • Moderator
    Team

    @tifsmo Try disabling audio_pwn_mode=2in config.txt



  • @substring

    tried that as well back then :). believe me i tried a lot of different things to get this working since i really wanted the old school crt experience i grew up with (alt. audio driver, different pal modes, even tried ntcs modes just out of desperation, etc, etc.) no such luck unfortunately with any configuration of cables, tvs or settings.

    but then again it might just be the rca port on my pi (although i also tried it on my old pi1 with the same result... so idk)

    now i just settled for a nice 1080p display with retro shader enabled and i'm still really happy with the experience.


  • Moderator
    Team

    @tifsmo i've done some tests lately on CRT, had no problems using NTSC (didn't even try PAL oddly, whereas I'm French haha)



  • @tifsmo

    I'll try to test my CRT as soon as possible, I don't know when this could be (expect 2-3 weeks at least), this TV isn't in my daily house.

    I'll give you my feedback, count on it.

    I was thinking on testing NTSC mode (my TV is compatible) all my roms are (U), as you might know, NTSC roms run faster than PAL (I suppose that's why @Substring tested NTSC).



  • @Substring mhmm weird... maybe i'll give it another go. thanks for your feedback.
    @Genaker thank you aswell, looking forward to hear how it turns out. best of luck. there is just nothing like playing some castelvania vi on halloween on an old crt tv :)

    cheers
    tim



  • I received the jack adapter yesterday. I don't know if this weekend I would be able to test it.

    I'll try to test my crt tv as soon as possible.

    I'll be back soon.



  • I have installed a new version of recalbox and Im unable to enter noobs.

    I have connected a wireless keyboard and pressing shift during booting doesn't open the edit menu.

    How can I change the config txt to edit the crt configuration???



  • Finally I was able to test my recalbox in my CRT TV.

    I had to use an old SD card with a Recalbox (version 4) that I wasn’t unable to update. With the new recalbox version I wasn’t unable to enter noobs and configure it. I set my Recalbox configuration to NTSC mode (my TV is PAL but it also works in NTSC), I followed the exact instructions from the forum.

    It works but I had a few issues to solve:
    -The audio had a very disgusting noise, I solved it configuring the audio output in “jack” mode.
    -The screen was cropped and I mainly solved it activating the overscan option. I had a better screen but I still have some cropped borders. I don’t know how to adjust the screen to fit my TV.
    -The image quality is not as good as the quality of my old PS2 console using the same type of connector, I tested the console to check the image quality and to compare it with the Recalbox. I think the problem is the cable I used with my Recalbox, it’s a cheap Chinese cable and I think is not very good. I’m going to make a new cable with good quality conectors and cable, I expect to get better image quality with this DIY cable.
    I think the overall image quality is good, but I expect to improve it with a good cable as I said before ( @tifsmo I don't know why you get terrible image quality).

    All I have to say is that you can use the Recalbox with an old CRT TV in order to get the retro style we had back in the 80’s and 90’s.

    I think that a good improvement for the Recalbox system will be the possibility to select the image output (Jack or HDMI) in order to avoid the config.txt configuration. If you can select the audio output, why not the image???. I have Openelec with Kodi in another raspberry and you can select the image output.

    Thanks to everybody for their support.



  • Yeah, you should try to use RCA cable like here I guess. I think there's a problem of bandwidth : a 800*600 CRT screen have 480k pixel. A pixel use 24 bits of information.
    If you want 30 images per second that is 480000 (all pixels) * 24 (bit per pixel) * 30 (images per secodns) = 345 600 000 bits per second aka 345.6 Mbps.
    This is meaning you need at least a category 6a copper pair cable.

    I'm making assomptions, but if it's just a cheap chineese copper pair, then you will have LOTS of white noise, because of physical stuff I don't want to bother you with.
    You would have white noise in the image and in the sound (white noise in image is your classic CRT "snow", and white noise in sound is the sound from that snow screen).
    In the image, it's a pixel or another that won't be displayed for 1/30 of a second, you just would notice a bad image stability/quality. But for sound you would hear that very clearly, because it's a 1D signal. This would be "either signal is ?wtf? either it's ok", instead of "just THAT pixel for a 1/30 of a second", in burst.

    (sound on top is just about +1Mbps (+192Mops, but I'm really not sure here), this means 6a is still ok. 6a was made for video anyway.)

    Check with a RCA (that one), or 2x 6a pair ! ;)

    Oh, and honestly, I'd also try to stay with PAL instead of NTSC. It's better for signal/noise, and it seems this is your main problem there.


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