<p>I was recording screencasts on Ubuntu 16.04 for youtube with my plantronics headset <em>C520-M</em> which worked just nice. I was using ffmpeg successfully.</p>

<p>Now I wanted to add some "live" video explaining things at a whiteboard, to make the video more attractive.</p>

<p>I was planning to record the live view with <em>Logitech HD Pro Webcam C920</em>, which also has builtin microphones that work not that bad. I can not use the headset for sound, since the whiteboard is too far away from the computer... (plus it might look weird).</p>

<p>I was using this command:</p>

<pre><code>ffmpeg -f v4l2 -framerate 25  -video_size 1280x720 -i /dev/video1 \
       -f alsa -ac 2 -thread_queue_size 1024 -i default \
        output.mkv
</code></pre>

<p>That always resulted in </p>

<blockquote>
  <p>[alsa @ 0x69d540] Thread message queue blocking; consider raising the thread_queue_size option (current value: 1024)</p>
</blockquote>

<p>The sound then stops at this point for the rest of the recording.</p>

<p>Thus I have a couple of questions:</p>

<ul>
<li>Why does it happen that the audio queue blocks?</li>
<li>How far should I raise the thread_queue_size?</li>
<li>How can I avoid that the audio queue blocks?</li>
<li>Which audio input should I use - actually I tried all of them an the sound stops at some point.</li>
</ul>

<p>Thanks for any hints.</p>

CC BY-SA 4.0
2020-05-12T06:47:26.273Z
Hi, similar problem here, what maximum value for `thread_queue_size` did you found to work for you?
Alf
CC BY-SA 4.0
2021-09-05T23:33:11.987Z
I have the same issue. I was thought thread_queue_size 1024 is a big number, but I still got that error after about 2 hours streaming
boygiandi
<ffmpeg><youtube>
Recording for Youtube: ffmpeg Thread message queue blocked
cornelinux
# Recording for Youtube: ffmpeg Thread message queue blocked

(Asked by: username_0 on 2018-01-25)

I was recording screencasts on Ubuntu 16.04 for youtube with my plantronics headset C520-M which worked just nice. I was using ffmpeg successfully.
Now I wanted to add some "live" video explaining things at a whiteboard, to make the video more attractive.
I was planning to record the live view with Logitech HD Pro Webcam C920, which also has builtin microphones that work not that bad. I can not use the headset for sound, since the whiteboard is too far away from the computer... (plus it might look weird).
I was using this command:
ffmpeg -f v4l2 -framerate 25  -video_size 1280x720 -i /dev/video1 \
       -f alsa -ac 2 -thread_queue_size 1024 -i default \
        output.mkv

That always resulted in 

[alsa @ 0x69d540] Thread message queue blocking; consider raising the thread_queue_size option (current value: 1024)

The sound then stops at this point for the rest of the recording.
Thus I have a couple of questions:

Why does it happen that the audio queue blocks?
How far should I raise the thread_queue_size?
How can I avoid that the audio queue blocks?
Which audio input should I use - actually I tried all of them an the sound stops at some point.

Thanks for any hints.

**Tags:** ffmpeg, youtube

> **Comments:**
> **username_1**: Hi, similar problem here, what maximum value for `thread_queue_size` did you found to work for you?  
> **username_2**: I have the same issue. I was thought thread_queue_size 1024 is a big number, but I still got that error after about 2 hours streaming  

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## 0 answers

