title: Creating animated AVIF with FFmpeg
body: <p>Edit: This did eventually complete, and the output file is fine. I am using a top-end MacBook M1 Pro computer. Is it normal for it to be this relentlessly slow? It was</p>
  <p>My input file is an <code>.mov</code>. I used this command:</p>
  <p><code>ffmpeg -i Jellyfish.mov Jellyfish.avif</code></p>
  <p>I also tried converting an MP4/h264 file.
  In both cases it took over 50 minutes.</p>
  <p>It's a 5 second long clip but it has taken about 20 minutes and the output file is still zero bytes.</p>
  <p>This is the output in my terminal:</p>
  <pre><code>Output #0, avif, to 'Jellyfish.avif':
    Metadata:
      major_brand     : mp42
      minor_version   : 0
      compatible_brands: mp42mp41isomavc1
      encoder         : Lavf59.27.100
    Stream #0:0(und): Video: av1 (av01 / 0x31307661), yuv420p(tv, bt709, progressive), 1280x720, q=2-31, 30 fps, 15360 tbn (default)
      Metadata:
        creation_time   : 2022-03-18T00:53:05.000000Z
        handler_name    : L-SMASH Video Handler
        vendor_id       : [0][0][0][0]
        encoder         : Lavc59.37.100 libaom-av1
      Side data:
        cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
  frame=    1 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A speed=   frame=   36 fps=1.4 q=0.0 size=       0kB time=00:00:00.03 bitrate=   0.0kbits/sframe=   37 fps=0.2 q=0.0 size=       0kB time=00:00:00.06 bitrate=   0.0kbits/sframe=   39 fps=0.2 q=0.0 size=       0kB time=00:00:00.13 bitrate=   0.0kbits/sframe=   41 fps=0.1 q=0.0 size=       0kB time=00:00:00.20 bitrate=   0.0kbits/sframe=   43 fps=0.1 q=0.0 size=       0kB time=00:00:00.26 bitrate=   0.0kbits/sframe=   45 fps=0.1 q=0.0 size=       0kB time=00:00:00.33 bitrate=   0.0kbits/sframe=   47 fps=0.1 q=0.0 size=       0kB time=00:00:00.40 bitrate=   0.0kbits/sframe=   49 fps=0.1 q=0.0 size=       0kB time=00:00:00.46 bitrate=   0.0kbits/sframe=   51 fps=0.1 q=0.0 size=       0kB time=00:00:00.53 bitrate=   0.0kbits/sframe=   53 fps=0.1 q=0.0 size=       0kB time=00:00:00.60 bitrate=   0.0kbits/sframe=   55 fps=0.1 q=0.0 size=       0kB time=00:00:00.66 bitrate=   0.0kbits/sframe=   57 fps=0.1 q=0.0 size=       0kB time=00:00:00.73 bitrate=   0.0kbits/sframe=   59 fps=0.1 q=0.0 size=       0kB time=00:00:00.80 bitrate=   0.0kbits/sframe=   61 fps=0.1 q=0.0 size=       0kB time=00:00:00.86 bitrate=   0.0kbits/sframe=   63 fps=0.1 q=0.0 size=       0kB time=00:00:00.93 bitrate=   0.0kbits/sframe=   65 fps=0.1 q=0.0 size=       0kB time=00:00:01.00 bitrate=   0.0kbits/sframe=   67 fps=0.1 q=0.0 size=       0kB time=00:00:01.06 bitrate=   0.0kbits/s speed=0.00103x
  </code></pre>
  <p>I copied the command <a href="https://avif.io/blog/tutorials/ffmpeg/" rel="nofollow noreferrer">avif.io</a></p>