html - 选择图像或视频

Question

我试图弄清楚如何在 html 中显示图像或视频。澄清一下，我想显示视频，但如果视频不存在或找不到文件，我希望显示默认图片。基本上是一个图像文件，如果视频不存在或不存在则显示。这甚至可能吗？我一直试图弄清楚这一点。没运气。任何帮助，将不胜感激。

Answer 1

查看这段代码，它提供 HTML5 视频回退到 Flash 和 Flash 回退到简单图像，完全不涉及 javascript！

<!-- first try HTML5 playback: if serving as XML, expand `controls` to `controls="controls"` and autoplay likewise -->
<!-- warning: playback does not work on iOS3 if you include the poster attribute! fixed in iOS4.0 -->
<video width="100%" height="200px" controls>

    <!-- MP4 must be first for iPad! -->
    <source src="__VIDEO__.MP4" type="video/mp4" /><!-- Safari / iOS video    -->
    <source src="__VIDEO__.OGV" type="video/ogg" /><!-- Firefox / Opera / Chrome10 -->

    <!-- fallback to Flash: -->
    <object width="640" height="360" type="application/x-shockwave-flash" data="__FLASH__.SWF">

         <!-- Firefox uses the `data` attribute above, IE/Safari uses the param below -->
         <param name="movie" value="__FLASH__.SWF" />
         <param name="flashvars" value="controlbar=over&amp;image=__POSTER__.JPG&amp;file=__VIDEO__.MP4" />

         <!-- fallback image. note the title field below, put the title of the video there -->
         <img src="__VIDEO__.JPG" width="640" height="360" alt="__TITLE__"
         title="No video playback capabilities, please download the video below" />
    </object>
</video>

<!-- you *must* offer a download link as they may be able to play the file locally. customise this bit all you want -->
<p>    
     <strong>Download Video:</strong>
     Closed Format: <a href="__VIDEO__.MP4">"MP4"</a>
     Open Format:   <a href="__VIDEO__.OGV">"Ogg"</a>
</p>​