Hello everyone,
This is my first thread, greetings to everyone.
I hope we will be able to solve my problem together as I've tried many many solutions and searched a lot but without any success for now... 
After a fresh install of Libreelec 10.0.1 (Matrix) on a Raspberry Pi 4, I don't have any audio output on my TV through HDMI.
Previously, I had a Libreelec 9.2.6 (Leia) distro and it was working by putting the following in config.txt:
# (old config.txt file in LE 9.2.6)
# HDMI without active display (optional)
hdmi_force_hotplug=1
# Audio over HDMI (optional)
hdmi_drive=2
# CEA mode
hdmi_group=1
# 1080p 60 Hz
hdmi_mode=16
But I read that starting from LE10, hdmi settings in config.txt are ignored.
Therefore, after the fresh install of Libreelec 10.0.1, I had to edit the cmdline.txt file to have some output.
boot=UUID=3010-5350 disk=UUID=a8e8a687-3b0f-472c-a2e4-3e8c903fd088 quiet video=HDMI-A-1:1280x720M@60D
With that line, I managed to have some video output through HDMI, but still no sound.
I'm using the HDMI port "0" (closer to the power plug) as I read that it was the recommended configuration when having a single external monitor.
The current content of my config.txt file is the following, I tried to play with the setting dtparam=audio=on but it seems to have no effect on HDMI audio.
When I enable this param in config.txt, I have some sound on the analog output (audio jack 3.5mm) though. But it doesn't help me since I want sound through HDMI 
# SPDX-License-Identifier: GPL-2.0-or-later
# Copyright (C) 2009-2014 Stephan Raue ([email protected])
# Copyright (C) 2016-present Team LibreELEC (https://libreelec.tv)
################################################################################
# Bootloader configuration
# config.txt version v1 (do not remove or change this line!)
################################################################################
# For more options and information see
# http://rpf.io/configtxt
################################################################################
# Default GPU memory split, 76MB are needed for H264 decoder
gpu_mem=76
# Don't send initial active source message.
# Avoids bringing CEC (enabled TV) out of standby and channel switch when
# rebooting.
hdmi_ignore_cec_init=1
################################################################################
# Include distribution specific config file if it exists.
################################################################################
[all]
include distroconfig.txt
# uncomment to enable infrared remote recevier connected to GPIO 18
#dtoverlay=gpio-ir,gpio_pin=18
#dtparam=audio=on
#audio_pwm_mode=1
Display More
Without dtparam=audio=on nor audio_pwm_mode (commented)
- Attached log
without_dtparam.txt
- I cannot select an audio output device in GUI (see image)
$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: vc4hdmi0 [vc4-hdmi-0], device 0: MAI PCM i2s-hifi-0 [MAI PCM i2s-hifi-0]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: vc4hdmi1 [vc4-hdmi-1], device 0: MAI PCM i2s-hifi-0 [MAI PCM i2s-hifi-0]
Subdevices: 1/1
Subdevice #0: subdevice #0
$ aplay -L
null
Discard all samples (playback) or generate zero samples (capture)
default
Default Audio Device
sysdefault
Default Audio Device
default:CARD=vc4hdmi0
vc4-hdmi-0, MAI PCM i2s-hifi-0
Default Audio Device
sysdefault:CARD=vc4hdmi0
vc4-hdmi-0, MAI PCM i2s-hifi-0
Default Audio Device
hdmi:CARD=vc4hdmi0,DEV=0
vc4-hdmi-0, MAI PCM i2s-hifi-0
HDMI Audio Output
default:CARD=vc4hdmi1
vc4-hdmi-1, MAI PCM i2s-hifi-0
Default Audio Device
sysdefault:CARD=vc4hdmi1
vc4-hdmi-1, MAI PCM i2s-hifi-0
Default Audio Device
hdmi:CARD=vc4hdmi1,DEV=0
vc4-hdmi-1, MAI PCM i2s-hifi-0
HDMI Audio Output
Display More
$ pactl list sinks
Sink #0
State: SUSPENDED
Name: auto_null
Description: Dummy Output
Driver: module-null-sink.c
Sample Specification: s16le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 6
Mute: no
Volume: front-left: 65536 / 100% / 0.00 dB, front-right: 65536 / 100% / 0.00 dB
balance 0.00
Base Volume: 65536 / 100% / 0.00 dB
Monitor Source: auto_null.monitor
Latency: 0 usec, configured 0 usec
Flags: DECIBEL_VOLUME LATENCY SET_FORMATS
Properties:
device.description = "Dummy Output"
device.class = "abstract"
device.icon_name = "audio-card"
Formats:
pcm
Display More
$ pactl list modules
Module #0
Name: module-native-protocol-unix
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "Native protocol (UNIX sockets)"
module.version = "14.2"
Module #1
Name: module-stream-restore
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "Automatically restore the volume/mute/device state of streams"
module.version = "14.2"
Module #2
Name: module-device-restore
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "Automatically restore the volume/mute state of devices"
module.version = "14.2"
Module #3
Name: module-card-restore
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "Automatically restore profile of cards"
module.version = "14.2"
Module #4
Name: module-default-device-restore
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "Automatically restore the default sink and source"
module.version = "14.2"
Module #5
Name: module-always-sink
Argument:
Usage counter: n/a
Properties:
module.author = "Colin Guthrie"
module.description = "Always keeps at least one sink loaded even if it's a null one"
module.version = "14.2"
Module #6
Name: module-null-sink
Argument: sink_name=auto_null sink_properties='device.description="Dummy Output"'
Usage counter: 0
Properties:
module.author = "Lennart Poettering"
module.description = "Clocked NULL sink"
module.version = "14.2"
Module #7
Name: module-suspend-on-idle
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "When a sink/source is idle for too long, suspend it"
module.version = "14.2"
Module #8
Name: module-dbus-protocol
Argument:
Usage counter: n/a
Properties:
module.author = "Tanu Kaskinen"
module.description = "D-Bus interface"
module.version = "14.2"
Module #9
Name: module-bluetooth-policy
Argument:
Usage counter: n/a
Properties:
module.author = "Frédéric Dalleau, Pali Rohár"
module.description = "Policy module to make using bluetooth devices out-of-the-box easier"
module.version = "14.2"
Module #10
Name: module-bluetooth-discover
Argument:
Usage counter: n/a
Properties:
module.author = "João Paulo Rechi Vita"
module.description = "Detect available Bluetooth daemon and load the corresponding discovery module"
module.version = "14.2"
Module #11
Name: module-bluez5-discover
Argument:
Usage counter: n/a
Properties:
module.author = "João Paulo Rechi Vita"
module.description = "Detect available BlueZ 5 Bluetooth audio devices and load BlueZ 5 Bluetooth audio drivers"
module.version = "14.2"
Module #12
Name: module-zeroconf-publish
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "mDNS/DNS-SD Service Publisher"
module.version = "14.2"
Module #13
Name: module-switch-on-connect
Argument:
Usage counter: n/a
Properties:
module.author = "Michael Terry"
module.description = "When a sink/source is added, switch to it or conditionally switch to it"
module.version = "14.2"
Display More
With dtparam=audio=on nor audio_pwm_mode (uncommented + reboot)
- Attached log
with_dtparam.txt
- I have the choice between 2 audio output devices in GUI (see image)
If I select ALSA: bcm2835... I have audio through the anolog output only (jack 3.5mm) but not through HDMI.
The other choice PULSE: Default does nothing and I am in the same situation than without dtparam=audio=on.
$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: vc4hdmi0 [vc4-hdmi-0], device 0: MAI PCM i2s-hifi-0 [MAI PCM i2s-hifi-0]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: vc4hdmi1 [vc4-hdmi-1], device 0: MAI PCM i2s-hifi-0 [MAI PCM i2s-hifi-0]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 2: Headphones [bcm2835 Headphones], device 0: bcm2835 Headphones [bcm2835 Headphones]
Subdevices: 8/8
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
Subdevice #4: subdevice #4
Subdevice #5: subdevice #5
Subdevice #6: subdevice #6
Subdevice #7: subdevice #7
Display More
$ aplay -L
null
Discard all samples (playback) or generate zero samples (capture)
default
Default Audio Device
sysdefault
Default Audio Device
default:CARD=vc4hdmi0
vc4-hdmi-0, MAI PCM i2s-hifi-0
Default Audio Device
sysdefault:CARD=vc4hdmi0
vc4-hdmi-0, MAI PCM i2s-hifi-0
Default Audio Device
hdmi:CARD=vc4hdmi0,DEV=0
vc4-hdmi-0, MAI PCM i2s-hifi-0
HDMI Audio Output
default:CARD=vc4hdmi1
vc4-hdmi-1, MAI PCM i2s-hifi-0
Default Audio Device
sysdefault:CARD=vc4hdmi1
vc4-hdmi-1, MAI PCM i2s-hifi-0
Default Audio Device
hdmi:CARD=vc4hdmi1,DEV=0
vc4-hdmi-1, MAI PCM i2s-hifi-0
HDMI Audio Output
default:CARD=Headphones
bcm2835 Headphones, bcm2835 Headphones
Default Audio Device
sysdefault:CARD=Headphones
bcm2835 Headphones, bcm2835 Headphones
Default Audio Device
Display More
$ pactl list sinks
Sink #0
State: SUSPENDED
Name: auto_null
Description: Dummy Output
Driver: module-null-sink.c
Sample Specification: s16le 2ch 44100Hz
Channel Map: front-left,front-right
Owner Module: 6
Mute: no
Volume: front-left: 65536 / 100% / 0.00 dB, front-right: 65536 / 100% / 0.00 dB
balance 0.00
Base Volume: 65536 / 100% / 0.00 dB
Monitor Source: auto_null.monitor
Latency: 0 usec, configured 0 usec
Flags: DECIBEL_VOLUME LATENCY SET_FORMATS
Properties:
device.description = "Dummy Output"
device.class = "abstract"
device.icon_name = "audio-card"
Formats:
pcm
Display More
$ pactl list modules
Module #0
Name: module-native-protocol-unix
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "Native protocol (UNIX sockets)"
module.version = "14.2"
Module #1
Name: module-stream-restore
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "Automatically restore the volume/mute/device state of streams"
module.version = "14.2"
Module #2
Name: module-device-restore
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "Automatically restore the volume/mute state of devices"
module.version = "14.2"
Module #3
Name: module-card-restore
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "Automatically restore profile of cards"
module.version = "14.2"
Module #4
Name: module-default-device-restore
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "Automatically restore the default sink and source"
module.version = "14.2"
Module #5
Name: module-always-sink
Argument:
Usage counter: n/a
Properties:
module.author = "Colin Guthrie"
module.description = "Always keeps at least one sink loaded even if it's a null one"
module.version = "14.2"
Module #6
Name: module-null-sink
Argument: sink_name=auto_null sink_properties='device.description="Dummy Output"'
Usage counter: 0
Properties:
module.author = "Lennart Poettering"
module.description = "Clocked NULL sink"
module.version = "14.2"
Module #7
Name: module-suspend-on-idle
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "When a sink/source is idle for too long, suspend it"
module.version = "14.2"
Module #8
Name: module-dbus-protocol
Argument:
Usage counter: n/a
Properties:
module.author = "Tanu Kaskinen"
module.description = "D-Bus interface"
module.version = "14.2"
Module #9
Name: module-bluetooth-policy
Argument:
Usage counter: n/a
Properties:
module.author = "Frédéric Dalleau, Pali Rohár"
module.description = "Policy module to make using bluetooth devices out-of-the-box easier"
module.version = "14.2"
Module #10
Name: module-bluetooth-discover
Argument:
Usage counter: n/a
Properties:
module.author = "João Paulo Rechi Vita"
module.description = "Detect available Bluetooth daemon and load the corresponding discovery module"
module.version = "14.2"
Module #11
Name: module-bluez5-discover
Argument:
Usage counter: n/a
Properties:
module.author = "João Paulo Rechi Vita"
module.description = "Detect available BlueZ 5 Bluetooth audio devices and load BlueZ 5 Bluetooth audio drivers"
module.version = "14.2"
Module #12
Name: module-zeroconf-publish
Argument:
Usage counter: n/a
Properties:
module.author = "Lennart Poettering"
module.description = "mDNS/DNS-SD Service Publisher"
module.version = "14.2"
Module #13
Name: module-switch-on-connect
Argument:
Usage counter: n/a
Properties:
module.author = "Michael Terry"
module.description = "When a sink/source is added, switch to it or conditionally switch to it"
module.version = "14.2"
Display More
Do not hesitate if you need additional info.
Thank you for having read my first Libreelec novel...
