Situation: Audio is not working over HDMI
DMT is only well defined in DVI and DVI can not do audio. Audio only works in CEA modes..
1# run to detect if tv/monitor mode
2tvservice -s
3
4# tvservice -m CEA
5# tvservice -m DMT
Uncomment the following in /boot/config.txt to force an HDMI mode. It can make audio work in DMT (computer monitor) modes.
NOTE: /boot/config.txt is kinda like the Linux version of BIOS settings
# Force the monitor to HDMI mode so that sound will be sent over HDMI cable
hdmi_drive=2
Now reboot for the changes to take effect
1sudo reboot