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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - ALSA module: tsched=0 causes skipping on nVidia HDMI output under QEMU-KVM"
href="https://bugs.freedesktop.org/show_bug.cgi?id=94763">94763</a>
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<th>Summary</th>
<td>ALSA module: tsched=0 causes skipping on nVidia HDMI output under QEMU-KVM
</td>
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<th>Product</th>
<td>PulseAudio
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>x86-64 (AMD64)
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<th>OS</th>
<td>Linux (All)
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>pavucontrol
</td>
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<th>Assignee</th>
<td>pulseaudio-bugs@lists.freedesktop.org
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<th>Reporter</th>
<td>dan@danedgecumbe.com
</td>
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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
</td>
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<pre>bool pa_alsa_may_tsched [modules/alsa/alsa-util.c] disables tsched if PA
determines that it is running within a VM.
This causes awful skipping audio on my system.
Removing the check enables the use of tsched and PA functions without a hitch.
Details
-------
Guest VM running under QEMU-KVM.
Arch Linux current 4.4.5-1-ARCH as of 2016/03/31
pulseaudio-git
commit 0f48b7c82378c32194b625d1fd886eee7f1e5928
Date: Sun Mar 13 23:56:54 2016 +0200
NVIDIA proprietary driver on nVidia GeForce 960GTX - using nVidia HDMI audio.
git blame appears to stem from 2009 - has support for tsched improved since
then?
53b046d5 src/modules/alsa/alsa-util.c (Lennart Poettering 2009-11-05 03:23:08
+0100 1482) /* We cannot depend on being woken up when we ask for in a
VM,
53b046d5 src/modules/alsa/alsa-util.c (Lennart Poettering 2009-11-05 03:23:08
+0100 1483) * so let's fallback to classic IO based playback then. */
I would go ahead and submit a pull request to disable this check but I'm unsure
of the ramifications across different virtualization solutions.</pre>
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