title: How to set proper bitrate for ffmpeg with hevc_nvenc?
body: <p>When I transcode video to H265 with following command, I get a bitrate about 600K and the quality is almost the same as the original.</p>
  
  <pre><code>ffmpeg -i data2.mp4 -c:v libx265 -c:a copy d2.mp4
  </code></pre>
  
  <p>However when I use the hevc_nvenc, I get a very high bitrate (about 2M), I need to have a bitrate as low as possible and keeping almost the same quality.</p>
  
  <pre><code>ffmpeg -i data2.mp4 -c:v hevc_nvenc -c:a copy d3.mp4
  </code></pre>
  
  <p>It works if I specify the output bitrate, but I want to know how to figure out the proper bitrate?</p>