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<base href="https://bugs.freedesktop.org/" />
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<th>Priority</th>
<td>medium
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<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - incorrect sample rate when recording a monitor"
href="https://bugs.freedesktop.org/show_bug.cgi?id=66424">66424</a>
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<th>CC</th>
<td>lennart@poettering.net
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<th>Assignee</th>
<td>pulseaudio-bugs@lists.freedesktop.org
</td>
</tr>
<tr>
<th>Summary</th>
<td>incorrect sample rate when recording a monitor
</td>
</tr>
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<th>QA Contact</th>
<td>pulseaudio-bugs@lists.freedesktop.org
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
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<th>OS</th>
<td>Linux (All)
</td>
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<th>Reporter</th>
<td>maarten-baert@hotmail.com
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<th>Hardware</th>
<td>x86-64 (AMD64)
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Version</th>
<td>unspecified
</td>
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<th>Component</th>
<td>core
</td>
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<th>Product</th>
<td>PulseAudio
</td>
</tr></table>
<p>
<div>
<pre>I was trying to record 'Monitor of Built-in Audio Analog Stereo' at 44.1kHz,
but for some reason PulseAudio actually recorded it at 48kHz. The result is a
44.1kHz audio file that actually contains 48kHz audio, so when it is played
back there is a very noticeable pitch shift and the length is also wrong. I
could reproduce this with my own application (which uses ALSA), Audacity (also
ALSA), arecord and parecord. For the last two I used these commands (while
playing a 44.1kHz MP3 in VLC):
arecord -f S16_LE -c 2 -r 44100 /tmp/alsa-test-44100.wav
parecord --format=s16le --channels=2 --rate=44100 /tmp/pa-test-44100.wav
I also tried recording at 48kHz, and this doesn't fix the problem. The
following commands:
arecord -f S16_LE -c 2 -r 48000 /tmp/alsa-test-48000.wav
parecord --format=s16le --channels=2 --rate=48000 /tmp/pa-test-48000.wav
... would also result in pitch-shifted sound.
I also tried repeatedly switching between the 'monitor' and my microphone (with
pavucontrol), and there was only a pitch shift when I recorded the 'monitor'.
I tried to change some settings in daemon.conf so I restarted PulseAudio, but
it turns out that just restarting made the problem go away. After that I
haven't been able to reproduce it. But I'm sure it was there: I still have the
pitch-shifted audio files and a list of packet timestamps from my application.
I am using Arch Linux and PulseAudio 4.0. I am using the default configuration
except for 'flat-volumes=no'.
I can upload the audio files and packet timestamps if they are useful.</pre>
</div>
</p>
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