<p>I have a file that has one video stream and one audio stream with 8 channels. I want to create a new file that will only contain the first 2 channels of the audio stream (no video). I can do this using the <a href="https://ffmpeg.org/ffmpeg-filters.html#pan" rel="nofollow">pan filter</a>. I also want to clip the file. I can do this using the <a href="https://www.ffmpeg.org/ffmpeg.html#toc-Main-options" rel="nofollow">-ss and -t options</a>. However, when I try to do both together, I get an error.</p>

<p>So, if I run:</p>

<pre><code>ffmpeg -i a.mov -filter_complex "[0:1]pan=2c|c0=c0|c1=c1[stereo]" -map "[stereo]" "a.audio.mov"
</code></pre>

<p>It works fine - I get the audio file with the correct channels.</p>

<p>But when I run:</p>

<pre><code>ffmpeg -i a.mov -filter_complex "[0:1]pan=2c|c0=c0|c1=c1[stereo]" -map "[stereo]" -ss 00:00:01 "a.audio.mov"
</code></pre>

<p>I get the following error</p>

<blockquote>
  <p>[trim for output stream 0:0 @ 0000000002145720] Cannot select channel
  layout for the link between filters trim for output stream 0:0 and
  output stream 0:0.<br>
  [trim for output stream 0:0 @ 0000000002145720] 
  Unknown channel layouts not supported, try specifying a channel layout
  using 'aformat=channel_layouts=something'.</p>
</blockquote>

<p>Anyone have any ideas what I'm doing wrong and how to fix it?</p>

CC BY-SA 3.0
2015-07-13T23:32:02.643Z
Your 2nd command works for me on a movie with a 6-channel AC3 track.  BTW, you probably want to use `-c:a libfdk_aac`, not the default AAC encoder.  Is your ffmpeg version old?  Does `-ss` work on that input stream when you aren't using that filter?
Peter Cordes
CC BY-SA 3.0
2015-07-21T08:13:18.367Z
Thanks @PeterCordes! I had an older version of FFmpeg - it works in the latest version!
charisk
<ffmpeg>
FFmpeg pan filter and clipping
charisk
# FFmpeg pan filter and clipping

(Asked by: username_0 on 2015-07-09)

I have a file that has one video stream and one audio stream with 8 channels. I want to create a new file that will only contain the first 2 channels of the audio stream (no video). I can do this using the pan filter. I also want to clip the file. I can do this using the -ss and -t options. However, when I try to do both together, I get an error.
So, if I run:
ffmpeg -i a.mov -filter_complex "[0:1]pan=2c|c0=c0|c1=c1[stereo]" -map "[stereo]" "a.audio.mov"

It works fine - I get the audio file with the correct channels.
But when I run:
ffmpeg -i a.mov -filter_complex "[0:1]pan=2c|c0=c0|c1=c1[stereo]" -map "[stereo]" -ss 00:00:01 "a.audio.mov"

I get the following error

[trim for output stream 0:0 @ 0000000002145720] Cannot select channel
  layout for the link between filters trim for output stream 0:0 and
  output stream 0:0.
  [trim for output stream 0:0 @ 0000000002145720] 
  Unknown channel layouts not supported, try specifying a channel layout
  using 'aformat=channel_layouts=something'.

Anyone have any ideas what I'm doing wrong and how to fix it?

**Tags:** ffmpeg

> **Comments:**
> **username_1**: Your 2nd command works for me on a movie with a 6-channel AC3 track.  BTW, you probably want to use `-c:a libfdk_aac`, not the default AAC encoder.  Is your ffmpeg version old?  Does `-ss` work on that input stream when you aren't using that filter?  
> **username_0**: Thanks @PeterCordes! I had an older version of FFmpeg - it works in the latest version!  

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## 0 answers

