Help with composite out.



  • Hi, just got a RP4 and wanted to connect it to an old CRT but I'm having major issues. Here's what I have:
    -Board model: Raspberry Pi 4
    -Recalbox version (build) : Recalbox (7.1.1 Reloaded)
    -Hardware (Micro SD, Power Supply, etc.): CanaKit Raspberry Pi 4 4GB Starter PRO Kit
    -Adafruit A/V and RCA (Composite Video, Audio) Cable for Raspberry Pi [ADA2881]

    This is my config file: https://pastebin.com/YyUJp08Y

    I'm brand new to all of this, I really am learning on the fly here, about SSH and commenting and un-commenting using # but nothing I try seems to work, I am getting audio from composite though, just never any sort of video. I really don't know anything about Linux or any of this so I'd appreciate any help because I'm at a total loss. I've tried reading up on these articles:
    https://www.raspberrypi.org/documentation/configuration/config-txt/video.md
    https://recalbox.gitbook.io/documentation/tutorials/video/crt/connecting-your-recalbox-to-a-crt-with-composite

    ...however I haven't figured it out, again, help would be greatly appreciated.


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    @Politician

    commenting and un-commenting using #

    First, understand that this type of configuration file reads all lines of code in it, regardless of where the code is, but as long as the code is written correctly.
    All lines starting with "#" (hashtag) or ";" (semicolons) are considered comments (you will notice that the descriptions and short texts for identification or help have a # at the beginning of the line), so when you want to invalidate a code, you just have to put the # sign at the beginning of the line and the configuration is not recognized, and when we want to activate a configuration, just remove the # sign from the front of the line (which is called uncomment).

    SSH

    According to wikipedia: SSH (Secure Shell) is a cryptographic network protocol for operating network services securely over an unsecured network.
    In short for an ordinary user: it is a "safe" way to access another device over the network.
    To do what you want there is no way to do it directly through the graphical interface that is accessible to the common user, it is necessary to start the device that you are running Recalbox on, and access it through the network, we usually do this with Putty or with WinSCP (I particularly like WinSCP):

    There are other ways to do this, and there are other tutorials on youtube on how to do this, you can do a little research if you need to, but the tutorials above are enough for you to understand.

    https://recalbox.gitbook.io/documentation/tutorials/video/crt/connecting-your-recalbox-to-a-crt-with-composite

    Exactly, this is the official tutorial, and to do that, you need to edit the config.txt file, and it is in the boot partition, which is write-protected to avoid problems, so, before editing it, you need to access the partition in write mode:

    After that, just try to follow what the tutorial says, commenting (#) the lines that start with "hdmi_", and adding the necessary lines corresponding to your hardware.

    Make sure that the composite cable is what is requested, and make sure you are connecting the other parts of the cable correctly (I once had a problem with an AV cable and a TV whose colors in the outputs did not match each other - I had to connect the yellow to the white, and the white to the yellow to work).



  • Hey, thanks for the response! I've been working the past few days to get Putty and WinSCP up and running, however I'm having a problem with the command mount -o remount,rw /boot as it doesn't seem to be changing anything? I also don't have quite a clear understanding on where my config file should be, I understand it's write protected but in the boot folder of recalbox, I find no such file, even after following the "Access a partition for writing" section of the tutorial you helped me with. Could you please clarify this a bit more, I really appreciate the help so far.


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    @Politician

    the command mount -o remount,rw /boot as it doesn't seem to be changing anything

    This command gives you write permission: If you are able to edit and save the config.txt file, then it is working, if not, you are doing or typing something wrong.

    but in the boot folder of recalbox, I find no such file

    The path is: /boot/config.txt
    It is only accessible via SSH (it is not possible to access directly with an adapter, the system must be working for the file to be accessible).

    If you are using WinSCP, go to root (move up the folder hierarchy until you can't move up any more), and there you will find the boot partition, inside it, the file config.txt.



  • The past few days, I've familiarized myself with this and it's helped a ton, I've leaned a lot about WinSCP and SSH but I'm still encountering a problem. I'm getting audio but no video, video is at best, flickering black and white static/fuzz/noise. I've tried swapping the yellow/white cables, I've tried every combination, even multiple TVs and still no video, only audio. I've even tried other software, formatting and re-formatting to test Lakka/Raspian/Retropie and still no composite video.


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    @Politician

    I'm getting audio but no video, video is at best, flickering black and white static/fuzz/noise. I've tried swapping the yellow/white cables

    I may be mistaken, but, it seems that the cable is the problem, did you test it with a multimeter, as the tutorial says?

    Caution, on camcorder cables, the video output may be on the right (red) audio jack.
    
    Also, the type of cable required is not really common.
    It is preferable to test with a Multimeter, in order to be sure that the cable you plan to use is
    corresponding to the diagram proposed above (an inversion of Ground and video on the jack
    leads to a jumping black & white image, sign of an unsuitable cable).
    


  • I did not because I do not own a multimeter. My cable is an Adafruit A/V and RCA (Composite Video, Audio) Cable for Raspberry Pi [ADA2881] so I just assumed it would be correct and good for the Pi.


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    @Politician This does not yet rule out the possibility of the cable being defective, for example.
    There are few possibilities:

    • Or the cable is defective,
    • Or you are setting something up wrong.

    What options have you modified?



  • This is my config, the things I've added are at the bottom of the config.
    https://pastebin.com/K51c7n3a


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    @Politician You forgot a detail that says in both tutorials.

    This tutorial says:

    • Finally, add hdmi_ignore_hotplug=1 to force the composite output.

    And this tutorial says:

    • hdmi_ignore_hotplug
      Setting hdmi_ignore_hotplug to 1 pretends that the HDMI hotplug signal is not asserted, so it appears that a HDMI display is not attached. In other words, composite output mode will be used, even if an HDMI monitor is detected.

    In other words:
    Uncomment this line (remove the # from the beginning of the line):
    # hdmi_ignore_hotplug = 1



  • My mistake, I should have mentioned I have tried that and still ended up with a flickering/junk screen. I think at this point it might be a bad/defective cable.


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    @Politician Maybe, but I can't guarantee it, unfortunately just testing to make sure ...



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