求助：MP4格式背景视频在IE11无法显示，主流浏览器正常

Alright, let's figure out why your background MP4 isn't playing in IE11—this is a super common compatibility headache, and I’ve got a few proven fixes for you:

• First, check your video’s encoding (most likely culprit)
  IE11 has super strict rules for MP4 playback: it only supports H.264 Baseline Profile (Level 3.0 or lower) paired with AAC-LC audio. If your video uses a higher profile (like High) or non-compliant audio codecs, IE11 will just ignore it.
  Use a tool like FFmpeg to re-encode your video to be IE11-friendly. Here’s a copy-paste command to do that:
  ffmpeg -i your-original-video.mp4 -c:v libx264 -profile:v baseline -level 3.0 -c:a aac -b:a 128k ie11-compatible-video.mp4

• Tweak your HTML video tag for IE11 quirks
  IE11 handles autoplay, muted, and loop attributes differently than Chrome/Firefox. Make your video tag look like this to avoid issues:

  <video autoplay muted loop poster="your-fallback-image.jpg">
    <source src="ie11-compatible-video.mp4" type="video/mp4">
    <!-- Fallback image if IE11 still won't play the video -->
    <img src="your-fallback-image.jpg" alt="Background content" />
  </video>
  

  A critical note: IE11 blocks autoplay for any video that isn’t muted, so the muted attribute is non-negotiable for background videos that auto-play. Skip the playsinline attribute too—IE11 doesn’t support it, and it can cause weird glitches.

• Verify your server’s Content-Type header
  Make sure your server sends the correct Content-Type: video/mp4 header when serving the MP4 file. If it’s set to something like application/octet-stream, IE11 won’t recognize it as a valid video. You can check this using IE11’s F12 DevTools: go to the Network tab, find your video request, and look at the response headers.

• Last resort: Flash fallback (use sparingly)
  If you absolutely have to support IE11 and the above fixes don’t work, you can add a Flash fallback. But keep in mind Flash is deprecated and insecure—most users have it disabled, so this should only be a final option.

内容的提问来源于stack exchange，提问作者RichardMiracles