页面加载时HTML video标签无法自动播放，是否需添加预加载器？

Hey there! Let's figure out why your video isn't autoplaying on page load. First off—you don't necessarily need a custom preloader to get autoplay working, but there are some critical browser rules and tag attributes you're missing here.

1. Browser Autoplay Policies Are the Main Culprit #

Modern browsers (Chrome, Firefox, Safari, etc.) have strict autoplay rules to prevent annoying auto-playing media with sound. For a video to autoplay on page load without user interaction, it must be muted. Your current code doesn't include the muted attribute, which is almost certainly why it's failing.

2. Fix Your Video Tag Code #

Here's the updated, working version of your code with key attributes added:

<video id="video_player" width="100%" autoplay muted playsinline>
  <source src="video/banner-video1.mp4" type="video/mp4">
</video>

Let's break down the important additions:

• autoplay: This is a boolean attribute—you don't need to set it to 1; just including the word autoplay is enough.
• muted: Required for autoplay without user interaction (per browser policies).
• playsinline: Fixes an issue on iOS Safari where videos force fullscreen playback; this keeps the video embedded in your page layout.

3. Do You Need a Preloader? #

The preload attribute controls whether the browser loads parts of the video before it's played, but it's not the solution to your autoplay problem. If your video takes a long time to load, you can add preload="auto" to hint the browser to load the video upfront:

<video id="video_player" width="100%" autoplay muted playsinline preload="auto">
  <source src="video/banner-video1.mp4" type="video/mp4">
</video>

Note: A "preloader" (like a custom loading spinner) is only needed if you want to show visual feedback while the video loads—but it won't fix the autoplay block itself.

4. Additional Troubleshooting Steps #

If it still doesn't work after adding the above attributes:

• Check your video path: Make sure video/banner-video1.mp4 is in the correct location relative to your HTML file. Open your browser's dev tools (F12) and check the "Network" tab for 404 errors on the video file.
• Verify video encoding: Ensure your MP4 uses H.264 video and AAC audio (the standard for web compatibility). Some encoded MP4s might not play in all browsers.
• Clear browser cache: Old cached versions of the video or page might be causing issues.

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