title: Use ffmpeg convert mp4 to hls m3u8 and reserver audio
body: <p>I have a mp4 file, input0.mp4. Now I want to convert it to a HLS and only reserver audio with one step. Now I can realease it with two steps as follows. First converting it to a mp3 file, second slicing mp3 file to m3m8.</p>
  
  <pre><code>ffmpeg -i input0.mp4 input0.mp3
  
  ffmpeg -i input0.mp3 -c:v libx264 -c:a aac -strict -2 -f hls -hls_list_size 0 output.m3u8
  </code></pre>
  
  <p>If I want to use ffmpeg to realease it with one step, how can I do it.</p>