<source>: The Media or Image Source element - HTML: HyperText Markup Language 编辑

The HTML <source> element specifies multiple media resources for the <picture>, the <audio> element, or the <video> element. It is an empty element, meaning that it has no content and does not have a closing tag. It is commonly used to offer the same media content in multiple file formats in order to provide compatibility with a broad range of browsers given their differing support for image file formats and media file formats.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

Content categories	None.
Permitted content	None, it is an empty element.
Tag omission	It must have a start tag, but must not have an end tag.
Permitted parents	A media element—<audio> or <video>—and it must be placed before any flow content or <track> element. A <picture> element, and it must be placed before the <img> element.
Implicit ARIA role	No corresponding role
Permitted ARIA roles	No role permitted
DOM interface	HTMLSourceElement

Attributes

This element includes the global attributes.

media

Media query of the resource's intended media; this should be used only in a <picture> element.

sizes

Is a list of source sizes that describes the final rendered width of the image represented by the source. Each source size consists of a comma-separated list of media condition-length pairs. This information is used by the browser to determine, before laying the page out, which image defined in srcset to use. Please note that sizes will have its effect only if width dimension descriptors are provided with srcset instead of pixel ratio values (200w instead of 2x for example).

The sizes attribute has an effect only when the <source> element is the direct child of a <picture> element.

src

Required for <audio> and <video>, address of the media resource. The value of this attribute is ignored when the <source> element is placed inside a <picture> element.

srcset

A list of one or more strings separated by commas indicating a set of possible images represented by the source for the browser to use. Each string is composed of:

1. One URL specifying an image.
2. A width descriptor, which consists of a string containing a positive integer directly followed by "w", such as 300w. The default value, if missing, is the infinity.
3. A pixel density descriptor, that is a positive floating number directly followed by "x". The default value, if missing, is 1x.

Each string in the list must have at least a width descriptor or a pixel density descriptor to be valid. Among the list, there must be only one string containing the same tuple of width descriptor and pixel density descriptor. The browser chooses the most adequate image to display at a given point of time.

The srcset attribute has an effect only when the <source> element is the direct child of a <picture> element.

type

The MIME media type of the resource, optionally with a codecs parameter.

If the type attribute isn't specified, the media's type is retrieved from the server and checked to see if the user agent can handle it; if it can't be rendered, the next <source> is checked. If the type attribute is specified, it's compared against the types the user agent can present, and if it's not recognized, the server doesn't even get queried; instead, the next <source> element is checked at once.

When used in the context of a <picture> element, the browser will fall back to using the image specified by the <picture> element's <img> child if it is unable to find a suitable image to use after examining every provided <source>.

Usage notes

The <source> element is an empty element (or void element), which means that it not only has no content but also has no closing tag. That is, you never use "</source>" in your HTML.

For information about image formats supported by web browsers and guidance on selecting appropriate formats to use, see our Image file type and format guide on the web. For details on the video and audio media types, you can use, see the Guide to media types formats used on the web.

Examples

Video example

This example demonstrates how to offer a video in Ogg format for users whose browsers support Ogg format, and a QuickTime format video for users whose browsers support that. If the audio or video element is not supported by the browser, a notice is displayed instead. If the browser supports the element but does not support any of the specified formats, an error event is raised and the default media controls (if enabled) will indicate an error. Be sure to reference our guide to media types and formats on the web for details on what media file formats you can use and how well they're supported by browsers.

<video controls>
  <source src="foo.webm" type="video/webm">
  <source src="foo.ogg" type="video/ogg">
  <source src="foo.mov" type="video/quicktime">
  I'm sorry; your browser doesn't support HTML5 video.
</video>

For more examples, the learning area article Video and audio content is a great resource.

Picture example

In this example, two <source> elements are included within the <picture>, providing versions of an image to use when the available space exceeds certain widths. If the available width is less than the smaller of these widths, the user agent will fall back to the image given by the <img> element.

<picture>
   <source srcset="mdn-logo-wide.png" media="(min-width: 800px)">
   <source srcset="mdn-logo-medium.png" media="(min-width: 600px)">
   <img src="mdn-logo-narrow.png" alt="MDN Web Docs">
</picture>

With the <picture> element, you must always include an <img> with a fallback image, with an alt attribute to ensure accessibility (unless the image is an irrelevant background decorative image).

Specifications

Specification	Status	Comment
HTML Living Standard The definition of '<source>' in that specification.	Living Standard

Browser compatibility

BCD tables only load in the browser

See also

• Guide to media types and formats on the web
• Image file type and format guide
• <picture> element
• <audio> element
• <video> element
• Web Performance