Archive for January 30th, 2014

Forcing Pulseaudio DisplayPort Volume Initialization

It turns out that the audio-over-HDMI/DisplayPort channel which, for whatever reason, is the only way to get audio out of the Optiplex 980 with the big Dell U2711 monitor starts up AT MAXIMUM VOLUME!¬†regardless of the GUI’s Pulseaudio mixer setting that’s diligently saved-and-restored across sessions. That makes a certain perverse sense, as the digital-to-analog converter & power amp live inside the monitor.

Manually adjusting the GUI mixer by one click, either up or down, forces the new setting out over the digital link to the monitor, after which the audio output corresponds to the mixer; I never remember that until just after some dipshit auto-play video lights up with a fanfare.

Setting the mixer to the same value doesn’t force an update, so the obvious solution (at least to me) of sending a fixed initial value doesn’t work; it’s optimized away. I think that’s why the initial update doesn’t happen: the stored volume is the same as the, ah, stored volume, so there’s no need to tell the monitor.

The automatic solution involves putting two more commands in my ever-growing ~/.config/

amixer -D pulse sset Master 26%
amixer -D pulse sset Master 1%-

That sets a rational level (which might be the same as the existing one from the previous session), then changing it by one tiny click to force the new value out to the monitor.

And then It Just Works…


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