Bug 621058

Summary:	Enable HDMI audio without activating the (visual) display
Product:	Gentoo Linux	Reporter:	gerion <gerion.entrup>
Component:	Current packages	Assignee:	Gentoo Linux bug wranglers <bug-wranglers>
Status:	RESOLVED NEEDINFO
Severity:	enhancement	CC:	jstein
Priority:	Normal
Version:	unspecified
Hardware:	All
OS:	Linux
Whiteboard:
Package list:		Runtime testing required:	---

Description gerion 2017-06-06 17:28:34 UTC

It would be cool to have the possibility to play sound over HDMI without activating the display or even have a display connected or more concrete to use HDMI only as an audio wire.

The use-case is given with any kind of A/V-receiver or sound system that cuts the audio out of the HDMI link and plays it separately. For example one can connect a Raspberry Pi over a digital connection with the audio system, etc.

I found no solution for this on Linux at all. The closest one I see is:
https://unix.stackexchange.com/questions/314248/activate-hdmi-output-without-using-as-desktop

I'm not sure what components are needed to be touched to implement this, X11/Wayland, the desktop, the kernel? This is the reason I post it here as a distribution feature request although it surely involves some upstream work.

The concrete bug description is the following:

Steps:
1. Play some sound over the ALSA device that represents your HDMI sound card. Do not activate the display before.

Expected:
Sound plays.

Got:
Sound does not play.


Steps:
1. Activate the display and then play sound and wait until the monitor is deactivated due to the power saving settings.

Expected:
Sound continues to play.

Got:
Sound stops.

Comment 1 Jonas Stein gentoo-dev

2017-06-06 19:58:41 UTC

It is sad to read that you have problems with the software. The situation seems to be a bit more complicate and requires some analysis.
We can not help you efficiently via bug tracker. The bug tracker aims rather on specific problems in .ebuilds and less on individual systems. 

I have had very good experience on the gentoo IRC [1] with questions like this. Of course there are also forums and mailing lists [2,3].
I hope you understand, that I will close the bug here therefore and wish you good luck on one of the mentioned channels [4].
Please reopen the ticket in order to provide an indication for an error in the ebuild.

[1] https://www.gentoo.org/get-involved/irc-channels/
[2] https://forums.gentoo.org/
[3] https://www.gentoo.org/get-involved/mailing-lists/all-lists.html
[4] https://www.gentoo.org/support/

Comment 2 gerion 2017-06-06 20:52:50 UTC

I'm pretty sure this is not an error in any ebuild and also cannot be solved nowadays without any kind of fake screen.

Anyway, I understand that you closed the bug. I filed it here, because I don't know a specific upstream and an upstream developer once told me to ask the distribution guys in this case. I'll ask in the forum, thank you for the advice.