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<div class="moz-cite-prefix">On 17/05/2016 11:56, John Veness wrote:<br>
</div>
<blockquote
cite="mid:6089de4a-25d3-0164-f69f-2b146234b1ca@pelago.org.uk"
type="cite"> The trick is how to send a similar empty bitstream
while in menus.<br>
<br>
So far I've been trying the aplay command, with no luck. If I do
just "aplay /usr/share/sounds/alsa/Noise.wav" the command looks
like it does something for a few seconds, but I hear no sound
output.<br>
<br>
If instead I do "aplay -L" to list the devices, then "aplay -D
dmix:CARD=HDMI,DEV=7 /usr/share/sounds/alsa/Noise.wav", which is
the same audio device I have selected in mythfrontend, the command
exits straight away, still no sound, and I get the error "aplay:
set_params:1239: Channels count not available".<br>
<br>
All of this testing is while mythfrontend isn't running.<br>
</blockquote>
<br>
I've got a bit further with this. The "dmix" device is the one I've
got selected in mythfrontend, because all the others have their left
and right channels swapped for some reason. But I can't seem to get
aplay to work with the dmix device. If I do "aplay -D
plughw:CARD=HDMI,DEV=7" instead, I hear sound - possibly with left
and right swapped but who cares when I'll be outputting silence.<br>
<br>
So I've got a loop like:<br>
<br>
while [ true ] ; do aplay -q -D
plughw:CARD=HDMI,DEV=7 silent.wav; sleep 150; done<br>
<br>
This seems to work, in that it doesn't cause the soundbar to go to
sleep. I found that a two second sample of "silence" didn't seem to
be enough to keep the soundbar awake. Eight seconds is enough, but I
haven't tried anything in between. The "sleep 150" sleeps for two
and a half minutes, so it isn't making a silent "sound" all the
time.<br>
<br>
If Myth happens to be outputting sound at the time the loop comes
around (i.e. every 2.5 minutes), the aplay command just fails as it
isn't able to output any sound, but that's fine and it will try
again in another 2.5 minutes.<br>
<br>
More problematic is what happens if someone presses play on a
recording in the exact time when aplay happens to be outputting
sound. In that case, Myth will start the video, but the playback
will be silent, with an error message saying it couldn't open the
sound device or similar.<br>
<br>
With a, say, 5 second sample every 2.5 minutes, there's a roughly
3.33% chance of this happening, or once in every 30 recordings
played back, which is often enough to be annoying, I think.<br>
<br>
I am considering looking into MythTV System Event Handlers, to do
something like "pkill aplay" when playback starts, but haven't tried
that yet.<br>
<br>
John<br>
<pre class="moz-signature" cols="72">--
John Veness, MythTV user, UK, DVB-T</pre>
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