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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - loopback on ladspa-sink: huge, persistent delay introduced by VT switch"
href="https://bugs.freedesktop.org/show_bug.cgi?id=104408">104408</a>
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<th>Summary</th>
<td>loopback on ladspa-sink: huge, persistent delay introduced by VT switch
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<th>Product</th>
<td>PulseAudio
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<th>Version</th>
<td>unspecified
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<th>Hardware</th>
<td>Other
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>modules
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<th>Assignee</th>
<td>pulseaudio-bugs@lists.freedesktop.org
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<th>Reporter</th>
<td>dap78@magex.hu
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<th>QA Contact</th>
<td>pulseaudio-bugs@lists.freedesktop.org
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<th>CC</th>
<td>lennart@poettering.net
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<p>
<div>
<pre>I use the following "chain" for VoIP audio processing:
# VoIP apps: higher tone
load-module module-ladspa-sink sink_name=spk-voip-eq-out plugin=mbeq_1197
label=mbeq
control=-30.0,-19.1,-18.6,-18.6,-18.6,-10.0,-8.0,-6.5,1.5,1.5,1.5,8.5,10.6,10.6,10.6
# VoIP apps: joint volume control
load-module module-null-sink sink_name=spk-voip-vol-out
sink_properties='device.description="Speaker VoIP Volume Out"'
load-module module-loopback source=spk-voip-vol-out.monitor
sink=spk-voip-eq-out latency_msec=4
The problem is a huge, persistent, 100% reproducible delay that appears on the
loopback after VT switch. The delay could be 5 seconds or even more, followable
on volume meters of pavucontrol. No problem if loopback's sink is other
loopback or hardware device instead of ladspa-sink OR user is a member of the
`audio` group thus access is not suspended on VT switch. Need to restart
pulseaudio to get rid of the introduced delay. Temporary moving of loopback's
sink to other loopback or hardware device eliminates the delay but it returns
after restore. Pulseaudio does not log anything that worth to mention.
I have nothing special in my PA config but I can share as is if necessary.
Fedora 27, pulseaudio-11.1-7.fc27.x86_64</pre>
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