title: FFmpeg change audio sample rate
body: <p>I need to increase the sample rate by 10%. Sample rates of input files are unknown. </p>
  
  <p>I found this. Example for 1 file:</p>
  
  <pre><code>ffmpeg -i xxx.mp3 -filter:a "asetrate=$(ffprobe -v error -show_entries stream=sample_rate -of default=noprint_wrappers=1:nokey=1 xxx.mp3)*1.1" -y xxx1.mp3
  </code></pre>
  
  <p>But is is not working and creates 0kb file.</p>
  
  <p>LOG:</p>
  
  <blockquote>
    <p>[asetrate @ 00000000024242e0] [Eval @ 00000000005fde80] Undefined
    constant or missing '(' in
    'ffprobe-verror-show_entriesstream=sample_rate-ofdefault=noprint_wrappers=1'
    [asetrate @ 00000000024242e0] Unable to parse option value "$(ffprobe
    -v error -show_entries stream=sample_rate -of default=noprint_wrappers=1" [Parsed_asetrate_0 @ 0000000000e6cb20]
    Option 'nokey' not found [AVFilterGraph @ 0000000002419ca0] Error
    initializing filter 'asetrate' with args '$(ffprobe -v error
    -show_entries stream=sample_rate -of default=noprint_wrappers=1:nokey=1 xxx.mp3)*1.1' Error reinitializing
    filters! Failed to inject frame into filter network: Option not found
    Error while processing the decoded data for stream #0:0 Conversion
    failed!</p>
  </blockquote>