Last Updated: February 25, 2016
· schmich

HTML5 video: Content-Type is important

If you're trying to play HTML5 video with the <video/> tag, ensure the correct Content-Type header is being sent for your source media.

Some browsers, such as Chrome, seem willing to play a video regardless of its Content-Type (perhaps through sniffing or file extensions), but others, such as IE, require a valid and supported value.

I ran into this while trying to play videos hosted on S3 with IE10:

<video controls autoplay>
  <source src="" type="video/mp4" />

Even with type attribute set to video/mp4, IE refused to play the video, saying only "Invalid Source" or "Error: Unsupported video type or invalid file path". Some searching yielded this blog post detailing common problems.

The error coming from the video element in IE was MEDIA_ERR_SRC_NOT_SUPPORTED. In my case, the source wasn't supported because the MIME type being sent was not supported.

> curl -I
HTTP/1.1 200 OK
Date: Fri, 14 Jun 2013 03:24:53 GMT
Last-Modified: Fri, 14 Jun 2013 03:24:40 GMT
Content-Type: application/octet-stream
Content-Length: 9227881
Server: AmazonS3

Apparently after uploading the video, S3 automatically set its Content-Type to application/octet-stream, which IE does not support.

This is normally not a problem when serving videos from a web server such as Apache, since the server is usually configured to send the Content-Type header based on the file extension, but many cloud storage services like S3 require you to specify your own metadata.

We were uploading videos using the AWS Ruby SDK, so the fix was to simply specify :content-type when uploading the file via S3Object#write:

obj.write(:content_type => 'video/mp4', ...)

If you need to support a wider range of MIME types, consider using the mime-types gem and MIME::Types.type_for.