5.1 surround centre audio coming out of subwoofer

  • Hey, I'm running LibreELEC 9.2.5 on a Pi4 with a HifiBerry Digi+ outputting over optical SPDIF to a 5.1 surround amp. My SD card died over the weekend so I had to reinstall everything and restore from a backup.


    Ever since then, all of the audio for the centre speaker has started coming out of the subwoofer instead of the centre speaker. The LFE channel is also coming out of the sub, so it's not just a simple case of swapping the speakers over, and since it's a single SPDIF cable there's nothing wrong hardware wise.


    My amp is an AC3 capable one, and transcoding is enabled in the audio settings. Without that turned on it doesn't even output 5.1 at all, and instead defaults to straight stereo.


    Does anyone know if there are any internal driver or config files that I can check? There are no settings within Kodi itself that I can change, there's no channel mapping at all.


    My config.txt has these lines at the bottom, otherwise it's the default file that ships with the OS.

    Code
    force_eeprom_read=0
    dtparam=i2s=on
    dtoverlay=hifiberry-digi

    I'm completely stumped with this one and I've not found anyone else who's had the same issue! Like I said it was absolutely fine before, and only started doing this when I replaced the SD card and reinstalled.

    Thanks

  • dtoverlay=hifiberry-digi is the only line you should add to config.txt.

    Flexin' vinyl, jammin' break beats. 8)

  • Mine may be a separate problem, but my system occasionally gets confused and mixes the channels up. It usually happens after a pause or a sleep/resume cycle.


    Suddenly center channel may be on rear right, and left front may be on center, with right front on rear right. Only way to fix it at that point is to reboot.

  • dtoverlay=hifiberry-digi is the only line you should add to config.txt.

    That's all I had in there initially, but it was the same.



    Mine may be a separate problem, but my system occasionally gets confused and mixes the channels up. It usually happens after a pause or a sleep/resume cycle.


    Suddenly center channel may be on rear right, and left front may be on center, with right front on rear right. Only way to fix it at that point is to reboot.

    I think yours might be unrelated. For me it's always the centre channel that's apparently hard coded itself to go over the sub. Persists across reboots.

  • My amp is an AC3 capable one, and transcoding is enabled in the audio settings. Without that turned on it doesn't even output 5.1 at all, and instead defaults to straight stereo.

    Maybe that's the wrong setup. Try pass-through without transcoding. At /storage/.kodi/userdata/guisettings.xml:

    Code
    <setting id="audiooutput.ac3passthrough" default="true">true</setting>
    <setting id="audiooutput.ac3transcode" default="true">false</setting>

    Flexin' vinyl, jammin' break beats. 8)

  • Maybe that's the wrong setup. Try pass-through without transcoding. At /storage/.kodi/userdata/guisettings.xml:

    Code
    <setting id="audiooutput.ac3passthrough" default="true">true</setting>
    <setting id="audiooutput.ac3transcode" default="true">false</setting>

    Modifying the xml file didn't save the change for some reason, it just reverted back as soon as I rebooted. When I turned off transcoding in the GUI I only got 2.0 stereo with nothing coming out of the sub at all. Looking at what the info in the GUI says, it reckons transcoding should be turned on if I'm using SPDIF. My setup doesn't support PCM multichannel over HDMI, hence the extra soundcard.

  • Did you set the general pass-through option at the audio settings? That's something else than the above AC3 pass-through setting.

    Flexin' vinyl, jammin' break beats. 8)

  • Yeah, there was only one passthrough device available. The output device at the top had two options, only the one I've got selected will output 5.1.


  • I don't have the same hardware. Maybe the HiFiBerry forum can help to find the right setup. /shrug


    PS: It could help to set expert settings back to default values, and start from there.

    Flexin' vinyl, jammin' break beats. 8)

  • PPS: Your HiFiBerry Digi+ has the ability to install firmware, right? Maybe something broke at the firmware while your microSD died. Try to re-install the firmware.

    Flexin' vinyl, jammin' break beats. 8)

  • Hey, so it's been a while but I went and bought a new Digi+ thinking it was that that had failed, but even with that and a new optical cable I'm still getting the same issue. The centre channel and LFE are still coming out of the subwoofer, which can only mean there's a software/driver issue somewhere.


    How can I get access to the actual driver the system uses? Maybe there's a way of altering channel mapping in there?

  • I never heard about channel mapping on LE. You had a working system before your microSD died, so I think it's not a driver issue.


    Because you have another HiFIBerry card, we can rule out a HiFiBerry firmware issue.


    On the other hand, the RPi has it's own firmware, too. LE installs the right firmware, but maybe something broke while your microSD died.


    My suggestion: Take another microSD, install Raspbian, and if Raspbian also has channel issues, try different RPi firmware on Raspbian.

    Flexin' vinyl, jammin' break beats. 8)

  • You can also change the firmware on LE, but it's easier on Raspbian. After changing the firmware, you can insert your LE card and instantly use it (firmware is at the chip).

    Flexin' vinyl, jammin' break beats. 8)