Pi 4 5.28 Sound

Since upgrading to 5.28 i get no sound. i have the following mods set and they have been set for some time.

hdmi_ignore_edid_audio=1
audio_pwm_mode=2

Very odd as sound was working fine before, what version of Pi 4 firmware is ideal as it seems to be related to firmware since everything else has not yielded any results.

I can’t comment on the audio aspect directly because – believe it or not – I don’t have an amplifier with a “line in” input to test the audio jack on the Pi, and plugging in headphones seems like a bad idea (impedance mismatch).

However, in general: RISC OS 5.28 was released with June 2020 firmware (the same as RC16) so if you upgraded from RC16 the firmware won’t have changed. Provided that you don’t have the 8GB model¹, pretty much any earlier firmware version should work (and I assume you’ve already tried the latest firmware). Do you still have a copy of the firmware you were using originally?

¹ The 8GB Pi 4 was announced in May 2020, so probably won’t work with firmware released before May 2020.

I had to add the following lines to config/txt to get hdmi audio working with RISC OS 5.28 on the Pi4;
hdmi_drive=2
hdmi_force_edid_audio=1

I’ve uploaded the Pi firmware files here if it helps Firmware Download

I’m using RISC OS 5.28 on Raspberry Pi model B+ and Raspberry Pi 2 with hdmi_ignore_edid_audio=1 and audio_pwm_mode=2 and I have clear sound output through audio jack. I don’t have Raspberry Pi 4 to test it, but it might be as well some problem with clashing config.txt parameters. I noticed that e.g. setting hdmi_safe=1 disables internal audio jack despite abovementioned options being set. Here is my working config.txt for reference:

fake_vsync_isr=1
framebuffer_swap=0
gpu_mem=64
init_emmc_clock=100000000
ramfsfile=CMOS
ramfsaddr=0×508000
kernel=RISCOS.IMG
hdmi_group=1
hdmi_mode=16
disable_overscan=1
hdmi_ignore_edid_audio=1
audio_pwm_mode=2

[pi4]
enable_gic=1

BTW. Have you tried replacing riscos.img on the FAT partition with an older ROM image? This could help to determine if it’s indeed an OS problem.

Hi Chris,

If you have the HDMI connected to the HDMI slot next to the USB C power input sound will work but if you connect it to the second HDMI slot by the jack then it doesn’t.

Tested on a Pi4 with Nov2020 firmware and 5.29 15th Nov 2020.

A similar issue affects the Pi400 where sound only is available on one of the two HDMI connections.

i would expect this as the system is designed for two monitors you would not want sound on the two of them at the same time i think there is config switch you can add to change it.

I have the same problem on a Pi-400 no sound. With Rasbian no problem
Update : A tip in this post said another plug on the Pi-400 this works as well . The one nearest the SD-card works.

Only one of the two HDMI sockets can carry sound over HDMI.

Only one of the two HDMI sockets can carry sound over HDMI.

There’s even an item in the Wiki these days