HDMI audio on Raspberry pi 3 b not working

Question

I've already seen Audio over HDMI not working on Pi 3 (audio not working though HDMI, but working though speakers) but the actions described by @Vader did not work for me. The fact is that it worked at some time in the past, without configuring /boot/config.txt or any other thing, but now it does not anymore.

I have a SONY BRAVIA TV, and following the instructions from https://www.raspberrypi.org/documentation/configuration/config-txt/README.md (edidparser output) I got all the specs from the TV, and I see:

HDMI:EDID features - videodef 0x80 !standby !suspend !active off; colour encoding:RGB444|YCbCr422; sRGB is not default colourspace; preferred format is native; does not support GTF
....
HDMI:EDID parsing v3 CEA extension 0
HDMI:EDID monitor support - underscan IT formats:no, basic audio:yes, yuv444:yes, yuv422:yes, #native DTD:0
....
HDMI:EDID found audio format 2 channels PCM, sample rate: 32|44|48 kHz, sample size: 16|20|24 bits
....
HDMI:EDID best score mode is now DMT (39) 1360x768p @ 60 Hz with pixel clock 85 MHz (score 5188004)

I also see:

$ /opt/vc/bin/tvservice -s 
state 0x12000a [HDMI CEA (4) RGB lim 16:9], 1280x720 @ 60.00Hz, progressive

As @Vader said I modified the /boot/config.txt to have the following:

# uncomment to force a specific HDMI mode (this will force VGA)
hdmi_group=1
hdmi_mode=4

# uncomment to force a HDMI mode rather than DVI. This can make audio work in
# DMT (computer monitor) modes
hdmi_drive=2
hdmi_force_edid_audio=1

I rebooted, and verified that the volume is right and not muted:

$ amixer
Simple mixer control 'PCM',0
  Capabilities: pvolume pvolume-joined pswitch pswitch-joined
  Playback channels: Mono
  Limits: Playback -10239 - 400
  Mono: Playback -2 [96%] [-0.02dB] [on]

,that the sound is routed through HDMI:

$ amixer cget numid=3
numid=3,iface=MIXER,name='PCM Playback Route'
  ; type=INTEGER,access=rw------,values=1,min=0,max=2,step=0
  : values=2

The sound driver is loaded:

$ lsmod | grep snd
snd_bcm2835            24427  1
snd_pcm                98501  1 snd_bcm2835
snd_timer              23968  1 snd_pcm
snd                    70032  5 snd_timer,snd_bcm2835,snd_pcm

I compiled the /opt/vc/src/hello_pi/hello_audio/ application and ran it:

$ sudo ./hello_audio.bin # I get sound though the speakers
Outputting audio to analogue

$ sudo ./hello_audio.bin 1 # I do not get sound in the TV though HDMI
Outputting audio to hdmi

I have the same behaviour with any application that I tested: speaker-test, aplay, lxmusic ... when I switch the audio output with amixer cset numid=3 2 or amixer cset numid=3 1

I do not have the .asoundrc and/or /etc/asound.conf files. I uploaded an ALSA diagnosis file to: http://www.alsa-project.org/db/?f=1c82d15d3df173fefc2b618f02cf7ccc172bf7d7, in case you want to see it (there you can find the output of alsactl )

The same HDMI cable and TV give sound with a windows barebone, so it is not a hw problem with those items. I doubt that it is a hw problem with the Rpi, because I borrowed another RPi3b and I tested it (same SD card) and it didn't work either.

My OS is Raspbian GNU/Linux 9.l

Any hint on what could have happened? Can I do something more to debug the issue?

Thanks in advance.

Answer 1

Please check in raspi-config Advanced Options that you are using the open GL Driver.
With the non-GL driver you will not be able to use digital sound.
Success!

Answer 2

It turned out that changing the HDMI cable did solve the issue, even with the default configuration of the RPi in raspbian 9.1. Maybe it was a too low quality HDMI cable, and as the Rpi pushes the data over the cable with very low power, the TV was not able to detect the signal. It worked with the barebone, probably because the barebone was emiting with a higher power.