HTML
Living Standard — Last Updated 1 October 2025
Living Standard — Last Updated 1 October 2025
video elementaudio elementtrack elementTrackEvent interfacevideo elementSupport in all current engines.
Support in all current engines.
controls attribute: Interactive content.src attribute:
zero or more track elements, then
transparent, but with no media element descendants.src attribute: zero or more source elements, then
zero or more track elements, then
transparent, but with no media element descendants.srccrossoriginposterpreloadautoplayplaysinlineloopmutedcontrolswidthheight[Exposed=Window]
interface HTMLVideoElement : HTMLMediaElement {
[HTMLConstructor] constructor();
[CEReactions, Reflect] attribute unsigned long width;
[CEReactions, Reflect] attribute unsigned long height;
readonly attribute unsigned long videoWidth;
readonly attribute unsigned long videoHeight;
[CEReactions, ReflectURL] attribute USVString poster;
[CEReactions, Reflect] attribute boolean playsInline;
};A video element is used for playing videos or movies, and audio files with
captions.
Content may be provided inside the video element. User agents
should not show this content to the user; it is intended for older web browsers which do
not support video, so that text can be shown to the users of these older browsers
informing them of how to access the video contents.
In particular, this content is not intended to address accessibility concerns. To
make video content accessible to the partially sighted, the blind, the hard-of-hearing, the deaf,
and those with other physical or cognitive disabilities, a variety of features are available.
Captions can be provided, either embedded in the video stream or as external files using the
track element. Sign-language tracks can be embedded in the video stream. Audio
descriptions can be embedded in the video stream or in text form using a WebVTT file
referenced using the track element and synthesized into speech by the user agent.
WebVTT can also be used to provide chapter titles. For users who would rather not use a media
element at all, transcripts or other textual alternatives can be provided by simply linking to
them in the prose near the video element. [WEBVTT]
The video element is a media element whose media data is
ostensibly video data, possibly with associated audio data.
The src, crossorigin,
preload, autoplay,
loop, muted, and controls attributes are the attributes common to all media elements.
The poster
attribute gives the URL of an image file that the user agent can show while no video
data is available. The attribute, if present, must contain a valid non-empty URL
potentially surrounded by spaces.
If the specified resource is to be used, then, when the element is created or when the poster attribute is set, changed, or removed, the user agent must
run the following steps to determine the element's poster frame (regardless of the
value of the element's show poster flag):
If there is an existing instance of this algorithm running for this video
element, abort that instance of this algorithm without changing the poster
frame.
If the poster attribute's value is the empty string
or if the attribute is absent, then there is no poster frame; return.
Let url be the result of encoding-parsing a URL given the poster attribute's value, relative to the element's node
document.
If url is failure, then return. There is no poster frame.
Let request be a new request whose URL is url, client is the element's node document's
relevant settings object, destination is "image", initiator type is "video",
credentials mode is "include", and whose use-URL-credentials flag is set.
Fetch request. This must delay the load event of the element's node document.
If an image is thus obtained, the poster frame is that image. Otherwise, there is no poster frame.
The image given by the poster attribute,
the poster frame, is intended to be a representative frame of the
video (typically one of the first non-blank frames) that gives the user an idea of what the video
is like.
The playsinline attribute is a boolean
attribute. If present, it serves as a hint to the user agent that the video ought to be
displayed "inline" in the document by default, constrained to the element's playback area, instead
of being displayed fullscreen or in an independent resizable window.
The absence of the playsinline
attribute does not imply that the video will display fullscreen by default. Indeed, most user
agents have chosen to play all videos inline by default, and in such user agents the playsinline attribute has no effect.
A video element represents what is given for the first matching condition in the
list below:
readyState attribute is either HAVE_NOTHING, or HAVE_METADATA but no video data has yet been obtained at
all, or the element's readyState attribute is any
subsequent value but the media resource does not have a video channel)video element represents its poster frame, if any,
or else transparent black with no natural dimensions.video element is paused, the current playback position is the first frame of video,
and the element's show poster flag is setvideo element represents its poster frame, if any,
or else the first frame of the video.video element is paused, and the
frame of video corresponding to the current playback
position is not available (e.g. because the video is seeking or buffering)video element is neither potentially playing nor paused (e.g. when seeking or stalled)video element represents the last frame of the video to have
been rendered.video element is pausedvideo element represents the frame of video corresponding to
the current playback position.video element has a video channel and is potentially
playing)video element represents the frame of video at the continuously
increasing "current" position. When the
current playback position changes such that the last frame rendered is no longer the
frame corresponding to the current playback position in the video, the new frame
must be rendered.Frames of video must be obtained from the video track that was selected when the event loop last reached step 1.
Which frame in a video stream corresponds to a particular playback position is defined by the video stream's format.
The video element also represents any text track cues whose text track cue active flag is set and whose
text track is in the showing mode, and any
audio from the media resource, at the current playback position.
Any audio associated with the media resource must, if played, be played synchronized with the current playback position, at the element's effective media volume. The user agent must play the audio from audio tracks that were enabled when the event loop last reached step 1.
In addition to the above, the user agent may provide messages to the user (such as "buffering", "no video loaded", "error", or more detailed information) by overlaying text or icons on the video or other areas of the element's playback area, or in another appropriate manner.
User agents that cannot render the video may instead make the element represent a link to an external video playback utility or to the video data itself.
When a video element's media resource has a video channel, the
element provides a paint source whose width is the media resource's
natural width, whose height is the
media resource's natural
height, and whose appearance is the frame of video corresponding to the current playback position, if that is available, or else
(e.g. when the video is seeking or buffering) its previous appearance, if any, or else (e.g.
because the video is still loading the first frame) blackness.
video.videoWidthSupport in all current engines.
video.videoHeightSupport in all current engines.
These attributes return the natural dimensions of the video, or 0 if the dimensions are not known.
The natural width and natural height of the media resource are the dimensions of the resource in CSS pixels after taking into account the resource's dimensions, aspect ratio, clean aperture, resolution, and so forth, as defined for the format used by the resource. If an anamorphic format does not define how to apply the aspect ratio to the video data's dimensions to obtain the "correct" dimensions, then the user agent must apply the ratio by increasing one dimension and leaving the other unchanged.
The videoWidth IDL attribute must return the natural width of the video in CSS pixels. The videoHeight IDL attribute must return the natural height of the video in CSS pixels. If the element's readyState attribute is HAVE_NOTHING, then the attributes must return 0.
Whenever the natural width
or natural height of the video changes
(including, for example, because the selected video
track was changed), if the element's readyState
attribute is not HAVE_NOTHING, the user agent must
queue a media element task given the media element to fire an event named resize at the media element.
The video element supports dimension attributes.
In the absence of style rules to the contrary, video content should be rendered inside the element's playback area such that the video content is shown centered in the playback area at the largest possible size that fits completely within it, with the video content's aspect ratio being preserved. Thus, if the aspect ratio of the playback area does not match the aspect ratio of the video, the video will be shown letterboxed or pillarboxed. Areas of the element's playback area that do not contain the video represent nothing.
In user agents that implement CSS, the above requirement can be implemented by using the style rule suggested in the Rendering section.
The natural width of a video element's playback area is the
natural width of the poster frame, if that is available and the
element currently represents its poster frame; otherwise, it is the natural width of the video resource, if that is
available; otherwise the natural width is missing.
The natural height of a video element's playback area is the
natural height of the poster frame, if that is available and the
element currently represents its poster frame; otherwise it is the natural height of the video resource, if that is
available; otherwise the natural height is missing.
The default object size is a width of 300 CSS pixels and a height of 150 CSS pixels. [CSSIMAGES]
User agents should provide controls to enable or disable the display of closed captions, audio description tracks, and other additional data associated with the video stream, though such features should, again, not interfere with the page's normal rendering.
User agents may allow users to view the video content in manners more suitable to the user,
such as fullscreen or in an independent resizable window. User agents may even trigger such a
viewing mode by default upon playing a video, although they should not do so when the playsinline attribute is specified. As with the other user
interface features, controls to enable this should not interfere with the page's normal rendering
unless the user agent is exposing a user
interface. In such an independent viewing mode, however, user agents may make full user
interfaces visible, even if the controls attribute is
absent.
User agents may allow video playback to affect system features that could interfere with the user's experience; for example, user agents could disable screensavers while video playback is in progress.
This example shows how to detect when a video has failed to play correctly:
<script>
function failed(e) {
// video playback failed - show a message saying why
switch (e.target.error.code) {
case e.target.error.MEDIA_ERR_ABORTED:
alert('You aborted the video playback.');
break;
case e.target.error.MEDIA_ERR_NETWORK:
alert('A network error caused the video download to fail part-way.');
break;
case e.target.error.MEDIA_ERR_DECODE:
alert('The video playback was aborted due to a corruption problem or because the video used features your browser did not support.');
break;
case e.target.error.MEDIA_ERR_SRC_NOT_SUPPORTED:
alert('The video could not be loaded, either because the server or network failed or because the format is not supported.');
break;
default:
alert('An unknown error occurred.');
break;
}
}
</script>
<p><video src="tgif.vid" autoplay controls onerror="failed(event)"></video></p>
<p><a href="tgif.vid">Download the video file</a>.</p>audio elementSupport in all current engines.
Support in all current engines.
controls attribute: Interactive content.controls attribute: Palpable content.src attribute:
zero or more track elements, then
transparent, but with no media element descendants.src attribute: zero or more source elements, then
zero or more track elements, then
transparent, but with no media element descendants.srccrossoriginpreloadautoplayloopmutedcontrols[Exposed=Window,
LegacyFactoryFunction=Audio(optional DOMString src)]
interface HTMLAudioElement : HTMLMediaElement {
[HTMLConstructor] constructor();
};An audio element represents a sound or audio stream.
Content may be provided inside the audio element. User agents
should not show this content to the user; it is intended for older web browsers which do
not support audio, so that text can be shown to the users of these older browsers
informing them of how to access the audio contents.
In particular, this content is not intended to address accessibility concerns. To
make audio content accessible to the deaf or to those with other physical or cognitive
disabilities, a variety of features are available. If captions or a sign language video are
available, the video element can be used instead of the audio element to
play the audio, allowing users to enable the visual alternatives. Chapter titles can be provided
to aid navigation, using the track element and a WebVTT file. And,
naturally, transcripts or other textual alternatives can be provided by simply linking to them in
the prose near the audio element. [WEBVTT]
The audio element is a media element whose media data is
ostensibly audio data.
The src, crossorigin,
preload, autoplay,
loop, muted, and controls attributes are the attributes common to all media elements.
audio = new Audio([ url ])Support in all current engines.
Returns a new audio element, with the src
attribute set to the value passed in the argument, if applicable.
A legacy factory function is provided for creating HTMLAudioElement objects (in
addition to the factory methods from DOM such as createElement()): Audio(src). When invoked, the legacy factory function
must perform the following steps:
Let document be the current global object's associated Document.
Let audio be the result of creating an
element given document, "audio", and the HTML
namespace.
Set an attribute value for
audio using "preload" and "auto".
If src is given, then set
an attribute value for audio using "src"
and src. (This will cause the user
agent to invoke the object's resource selection
algorithm before returning.)
Return audio.
track elementSupport in all current engines.
Support in all current engines.
Support in all current engines.
kindsrcsrclanglabeldefault[Exposed=Window]
interface HTMLTrackElement : HTMLElement {
[HTMLConstructor] constructor();
[CEReactions] attribute DOMString kind;
[CEReactions, ReflectURL] attribute USVString src;
[CEReactions, Reflect] attribute DOMString srclang;
[CEReactions, Reflect] attribute DOMString label;
[CEReactions, Reflect] attribute boolean default;
const unsigned short NONE = 0;
const unsigned short LOADING = 1;
const unsigned short LOADED = 2;
const unsigned short ERROR = 3;
readonly attribute unsigned short readyState;
readonly attribute TextTrack track;
};The track element allows authors to specify explicit external timed text tracks for media elements. It
does not represent anything on its own.
The kind attribute is
an enumerated attribute with the following keywords and states:
| Keyword | State | Brief description |
|---|---|---|
subtitles
| Subtitles | Transcription or translation of the dialogue, suitable for when the sound is available but not understood (e.g. because the user does not understand the language of the media resource's audio track). Overlaid on the video. |
captions
| Captions | Transcription or translation of the dialogue, sound effects, relevant musical cues, and other relevant audio information, suitable for when sound is unavailable or not clearly audible (e.g. because it is muted, drowned-out by ambient noise, or because the user is deaf). Overlaid on the video; labeled as appropriate for the hard-of-hearing. |
descriptions
| Descriptions | Textual descriptions of the video component of the media resource, intended for audio synthesis when the visual component is obscured, unavailable, or not usable (e.g. because the user is interacting with the application without a screen while driving, or because the user is blind). Synthesized as audio. |
chapters
| Chapters metadata | Tracks intended for use from script. Not displayed by the user agent. |
metadata
| Metadata |
The attribute's missing value default is the subtitles state, and its invalid value default is the metadata state.
The src attribute
gives the URL of the text track data. The value must be a valid non-empty URL
potentially surrounded by spaces. This attribute must be present.
The element has an associated track URL (a string), initially the empty string.
When the element's src attribute is set, run these steps:
Let trackURL be failure.
Let value be the element's src attribute
value.
If value is not the empty string, then set trackURL to the result of encoding-parsing-and-serializing a URL given value, relative to the element's node document.
Set the element's track URL to trackURL if it is not failure; otherwise to the empty string.
If the element's track URL identifies a WebVTT resource, and the element's kind attribute is not in the chapters metadata or metadata state, then the WebVTT file must be a
WebVTT file using cue text. [WEBVTT]
The srclang
attribute gives the language of the text track data. The value must be a valid BCP 47 language
tag. This attribute must be present if the element's kind
attribute is in the subtitles state.
[BCP47]
If the element has a srclang attribute whose value is
not the empty string, then the element's track language is the value of the attribute.
Otherwise, the element has no track language.
The label attribute
gives a user-readable title for the track. This title is used by user agents when listing subtitle, caption, and audio description tracks in their user interface.
The value of the label attribute, if the attribute is
present, must not be the empty string. Furthermore, there must not be two track
element children of the same media element whose kind attributes are in the same state, whose srclang attributes are both missing or have values that
represent the same language, and whose label attributes are
again both missing or both have the same value.
If the element has a label attribute whose value is not
the empty string, then the element's track label is the value of the attribute.
Otherwise, the element's track label is an empty string.
The default
attribute is a boolean attribute, which, if specified, indicates that the track is to
be enabled if the user's preferences do not indicate that another track would be more
appropriate.
Each media element must have no more than one track element child
whose kind attribute is in the subtitles or captions state and whose default attribute is specified.
Each media element must have no more than one track element child
whose kind attribute is in the description state and whose default attribute is specified.
Each media element must have no more than one track element child
whose kind attribute is in the chapters metadata state and whose default attribute is specified.
There is no limit on the number of track elements whose kind attribute is in the metadata state and whose default attribute is specified.
track.readyStateReturns the text track readiness state, represented by a number from the following list:
track.NONE (0)The text track not loaded state.
track.LOADING (1)The text track loading state.
track.LOADED (2)The text track loaded state.
track.ERROR (3)The text track failed to load state.
track.trackReturns the TextTrack object corresponding to the text track of the
track element.
The readyState attribute must return the numeric value
corresponding to the text track readiness state of the track element's
text track, as defined by the following list:
NONE (numeric value 0)LOADING (numeric value 1)LOADED (numeric value 2)ERROR (numeric value 3)The track IDL
attribute must, on getting, return the track element's text track's
corresponding TextTrack object.
The kind IDL
attribute must reflect the content attribute of the same name, limited to only
known values.
This video has subtitles in several languages:
<video src="brave.webm">
<track kind=subtitles src=brave.en.vtt srclang=en label="English">
<track kind=captions src=brave.en.hoh.vtt srclang=en label="English for the Hard of Hearing">
<track kind=subtitles src=brave.fr.vtt srclang=fr lang=fr label="Français">
<track kind=subtitles src=brave.de.vtt srclang=de lang=de label="Deutsch">
</video>(The lang attributes on the last two describe the language of
the label attribute, not the language of the subtitles
themselves. The language of the subtitles is given by the srclang attribute.)
HTMLMediaElement objects (audio and video, in this
specification) are simply known as media elements.
Support in all current engines.
Support in all current engines.
Support in all current engines.
Support in all current engines.
Support in all current engines.
Support in all current engines.
enum CanPlayTypeResult { "" /* empty string */, "maybe", "probably" };
typedef (MediaStream or MediaSource or Blob) MediaProvider;
[Exposed=Window]
interface HTMLMediaElement : HTMLElement {
// error state
readonly attribute MediaError? error;
// network state
[CEReactions, ReflectURL] attribute USVString src;
attribute MediaProvider? srcObject;
readonly attribute USVString currentSrc;
[CEReactions] attribute DOMString? crossOrigin;
const unsigned short NETWORK_EMPTY = 0;
const unsigned short NETWORK_IDLE = 1;
const unsigned short NETWORK_LOADING = 2;
const unsigned short NETWORK_NO_SOURCE = 3;
readonly attribute unsigned short networkState;
[CEReactions] attribute DOMString preload;
readonly attribute TimeRanges buffered;
undefined load();
CanPlayTypeResult canPlayType(DOMString type);
// ready state
const unsigned short HAVE_NOTHING = 0;
const unsigned short HAVE_METADATA = 1;
const unsigned short HAVE_CURRENT_DATA = 2;
const unsigned short HAVE_FUTURE_DATA = 3;
const unsigned short HAVE_ENOUGH_DATA = 4;
readonly attribute unsigned short readyState;
readonly attribute boolean seeking;
// playback state
attribute double currentTime;
undefined fastSeek(double time);
readonly attribute unrestricted double duration;
object getStartDate();
readonly attribute boolean paused;
attribute double defaultPlaybackRate;
attribute double playbackRate;
attribute boolean preservesPitch;
readonly attribute TimeRanges played;
readonly attribute TimeRanges seekable;
readonly attribute boolean ended;
[CEReactions, Reflect] attribute boolean autoplay;
[CEReactions, Reflect] attribute boolean loop;
Promise<undefined> play();
undefined pause();
// controls
[CEReactions, Reflect] attribute boolean controls;
attribute double volume;
attribute boolean muted;
[CEReactions, Reflect="muted"] attribute boolean defaultMuted;
// tracks
[SameObject] readonly attribute AudioTrackList audioTracks;
[SameObject] readonly attribute VideoTrackList videoTracks;
[SameObject] readonly attribute TextTrackList textTracks;
TextTrack addTextTrack(TextTrackKind kind, optional DOMString label = "", optional DOMString language = "");
};The media element attributes, src, crossorigin, preload, autoplay,
loop, muted, and
controls, apply to all media elements. They are defined in this section.
Media elements are used to present audio data, or video and audio data, to the user. This is referred to as media data in this section, since this section applies equally to media elements for audio or for video. The term media resource is used to refer to the complete set of media data, e.g. the complete video file, or complete audio file.
A media resource has an associated
origin, which is either "none",
"multiple", "rewritten", or an
origin. It is initially set to "none".
A media resource can have multiple audio and video tracks. For the purposes of a
media element, the video data of the media resource is only that of the
currently selected track (if any) as given by the element's videoTracks attribute when the event loop last
reached step 1, and the audio data of the media resource is the result of mixing all
the currently enabled tracks (if any) given by the element's audioTracks attribute when the event loop last
reached step 1.
Both audio and video elements can be used for both audio
and video. The main difference between the two is simply that the audio element has
no playback area for visual content (such as video or captions), whereas the video
element does.
Each media element has a unique media element event task source.
To queue a media element task with a media element element and a series of steps steps, queue an element task on the media element's media element event task source given element and steps.
Support in all current engines.
media.errorSupport in all current engines.
Returns a MediaError object representing the current error state of the
element.
Returns null if there is no error.
All media elements have an associated error status, which
records the last error the element encountered since its resource selection algorithm was last invoked. The
error attribute,
on getting, must return the MediaError object created for this last error, or null if
there has not been an error.
[Exposed=Window]
interface MediaError {
const unsigned short MEDIA_ERR_ABORTED = 1;
const unsigned short MEDIA_ERR_NETWORK = 2;
const unsigned short MEDIA_ERR_DECODE = 3;
const unsigned short MEDIA_ERR_SRC_NOT_SUPPORTED = 4;
readonly attribute unsigned short code;
readonly attribute DOMString message;
};media.error.codeSupport in all current engines.
Returns the current error's error code, from the list below.
media.error.messageSupport in all current engines.
Returns a specific informative diagnostic message about the error condition encountered. The message and message format are not generally uniform across different user agents. If no such message is available, then the empty string is returned.
Every MediaError object has a message, which is a string, and a code, which is one of the following:
MEDIA_ERR_ABORTED (numeric value 1)MEDIA_ERR_NETWORK (numeric value 2)MEDIA_ERR_DECODE (numeric value 3)MEDIA_ERR_SRC_NOT_SUPPORTED (numeric value 4)src
attribute or assigned media provider object was not suitable.To create a MediaError, given an
error code which is one of the above values, return a new MediaError object whose
code is the given error code and whose message is a string containing any details the user
agent is able to supply about the cause of the error condition, or the empty string if the user
agent is unable to supply such details. This message string must not contain only the information
already available via the supplied error code; for example, it must not simply be a translation of
the code into a string format. If no additional information is available beyond that provided by
the error code, the message must be set to the
empty string.
The src content
attribute on media elements gives the URL of the
media resource (video, audio) to show. The attribute, if present, must contain a valid
non-empty URL potentially surrounded by spaces.
If the itemprop attribute is specified on the media
element, then the src attribute must also be
specified.
The crossorigin content attribute on media elements is a CORS settings attribute.
If a media element is created with a
src attribute, the user agent must immediately invoke the
media element's resource selection
algorithm.
If a src attribute of a media element is set
or changed, the user agent must invoke the media element's media element load
algorithm. (Removing the src attribute does
not do this, even if there are source elements present.)
Support in all current engines.
The crossOrigin IDL attribute must reflect
the crossorigin content attribute, limited to
only known values.
A media provider object is an object that can represent a media
resource, separate from a URL. MediaStream objects,
MediaSource objects, and Blob objects are all media provider objects.
Each media element can have an assigned media provider object, which is a media provider object. When a media element is created, it has no assigned media provider object.
media.srcObject [ = source ]Support in one engine only.
Allows the media element to be assigned a media provider object.
media.currentSrcSupport in all current engines.
Returns the URL of the current media resource, if any.
Returns the empty string when there is no media resource, or it doesn't have a URL.
The currentSrc IDL attribute must initially be set to the
empty string. Its value is changed by the resource
selection algorithm defined below.
The srcObject IDL attribute, on getting, must return the
element's assigned media provider object, if any, or null otherwise. On setting, it
must set the element's assigned media provider object to the new value, and then
invoke the element's media element load algorithm.
There are three ways to specify a media resource: the srcObject IDL attribute, the src content attribute, and source elements. The IDL
attribute takes priority, followed by the content attribute, followed by the elements.
A media resource can be described in terms of its type, specifically a
MIME type, in some cases with a codecs parameter. (Whether the
codecs parameter is allowed or not depends on the MIME type.)
[RFC6381]
Types are usually somewhat incomplete descriptions; for example "video/mpeg" doesn't say anything except what the container type is, and even a
type like "video/mp4; codecs="avc1.42E01E, mp4a.40.2"" doesn't
include information like the actual bitrate (only the maximum bitrate). Thus, given a type, a user
agent can often only know whether it might be able to play media of that type (with
varying levels of confidence), or whether it definitely cannot play media of that
type.
A type that the user agent knows it cannot render is one that describes a resource that the user agent definitely does not support, for example because it doesn't recognize the container type, or it doesn't support the listed codecs.
The MIME type "application/octet-stream" with no parameters is never
a type that the user agent knows it cannot render. User agents must treat that type
as equivalent to the lack of any explicit Content-Type metadata
when it is used to label a potential media resource.
Only the MIME type "application/octet-stream" with no
parameters is special-cased here; if any parameter appears with it, it will be treated just like
any other MIME type. This is a deviation from the rule that unknown MIME type parameters should be
ignored.
media.canPlayType(type)Support in all current engines.
Returns the empty string (a negative response), "maybe", or "probably" based on how confident the user agent is that it can play media resources of the given type.
The canPlayType(type) method must return
the empty string if type is a type
that the user agent knows it cannot render or is the type
"application/octet-stream"; it must return "probably" if
the user agent is confident that the type represents a media resource that it can
render if used in with this audio or video element; and it must return
"maybe" otherwise. Implementers are encouraged to
return "maybe" unless the type can be
confidently established as being supported or not. Generally, a user agent should never return
"probably" for a type that allows the codecs parameter if that parameter is not present.
This script tests to see if the user agent supports a (fictional) new format to dynamically
decide whether to use a video element:
<section id="video">
<p><a href="playing-cats.nfv">Download video</a></p>
</section>
<script>
const videoSection = document.getElementById('video');
const videoElement = document.createElement('video');
const support = videoElement.canPlayType('video/x-new-fictional-format;codecs="kittens,bunnies"');
if (support === "probably") {
videoElement.setAttribute("src", "playing-cats.nfv");
videoSection.replaceChildren(videoElement);
}
</script>The type attribute of the
source element allows the user agent to avoid downloading resources that use formats
it cannot render.
media.networkStateSupport in all current engines.
Returns the current state of network activity for the element, from the codes in the list below.
As media elements interact with the network, their current
network activity is represented by the networkState attribute. On getting, it must return
the current network state of the element, which must be one of the following values:
NETWORK_EMPTY (numeric value 0)NETWORK_IDLE (numeric value 1)NETWORK_LOADING (numeric value 2)NETWORK_NO_SOURCE (numeric value 3)The resource selection algorithm defined
below describes exactly when the networkState
attribute changes value and what events fire to indicate changes in this state.
media.load()Support in all current engines.
Causes the element to reset and start selecting and loading a new media resource from scratch.
All media elements have a can autoplay flag, which must begin in the true state, and a delaying-the-load-event flag, which must begin in the false state. While the delaying-the-load-event flag is true, the element must delay the load event of its document.
When the load()
method on a media element is invoked, the user agent must run the media element
load algorithm.
A media element has an associated boolean is currently stalled, which is initially false.
The media element load algorithm consists of the following steps.
Set this element's is currently stalled to false.
Abort any already-running instance of the resource selection algorithm for this element.
Let pending tasks be a list of all tasks from the media element's media element event task source in one of the task queues.
For each task in pending tasks that would resolve pending play promises or reject pending play promises, immediately resolve or reject those promises in the order the corresponding tasks were queued.
Remove each task in pending tasks from its task queue.
Basically, pending events and callbacks are discarded and promises in-flight to be resolved/rejected are resolved/rejected immediately when the media element starts loading a new resource.
If the media element's networkState is set to NETWORK_LOADING or NETWORK_IDLE, queue a media element task
given the media element to fire an event
named abort at the media element.
If the media element's networkState
is not set to NETWORK_EMPTY, then:
Queue a media element task given the media element to fire an event named emptied at the media element.
If a fetching process is in progress for the media element, the user agent should stop it.
If the media element's assigned media provider object is a
MediaSource object, then detach it.
If readyState is not set to HAVE_NOTHING, then set it to that state.
If the paused attribute is false, then:
Set the paused attribute to true.
Take pending play promises and reject pending play promises
with the result and an "AbortError"
DOMException.
If seeking is true, set it to false.
Set the current playback position to 0.
Set the official playback position to 0.
If this changed the official playback position, then queue a media
element task given the media element to fire an event named timeupdate at the media element.
Set the timeline offset to Not-a-Number (NaN).
Update the duration attribute to Not-a-Number
(NaN).
The user agent will not fire a durationchange event for this particular change of
the duration.
Set the playbackRate attribute to the value of
the defaultPlaybackRate attribute.
Set the error attribute to null and the
can autoplay flag to true.
Invoke the media element's resource selection algorithm.
Playback of any previously playing media resource for this element stops.
The resource selection algorithm for a media element is as follows. This algorithm is always invoked as part of a task, but one of the first steps in the algorithm is to return and continue running the remaining steps in parallel. In addition, this algorithm interacts closely with the event loop mechanism; in particular, it has synchronous sections (which are triggered as part of the event loop algorithm). Steps in such sections are marked with ⌛.
Set the element's networkState attribute to
the NETWORK_NO_SOURCE value.
Set the element's show poster flag to true.
Set the media element's delaying-the-load-event flag to true (this delays the load event).
Await a stable state, allowing the task that invoked this algorithm to continue. The synchronous section consists of all the remaining steps of this algorithm until the algorithm says the synchronous section has ended. (Steps in synchronous sections are marked with ⌛.)
⌛ If the media element's blocked-on-parser flag is false, then populate the list of pending text tracks.
⌛ If the media element has an assigned media provider object, then let mode be object.
⌛ Otherwise, if the media element has no assigned media provider
object but has a src
attribute, then let mode be attribute.
⌛ Otherwise, if the media element does not have an assigned media provider
object and does not have a src attribute, but does have a source element child, then
let mode be children and let candidate
be the first such source element child in tree order.
⌛ Otherwise, the media element has no assigned media provider
object and has neither a src attribute nor a source element child:
⌛ Set the networkState to NETWORK_EMPTY.
⌛ Set the element's delaying-the-load-event flag to false. This stops delaying the load event.
End the synchronous section and return.
⌛ Set the media element's networkState to NETWORK_LOADING.
⌛ Queue a media element task given the media element to
fire an event named loadstart at the media element.
Run the appropriate steps from the following list:
⌛ Set the currentSrc attribute to
the empty string.
End the synchronous section, continuing the remaining steps in parallel.
Run the resource fetch algorithm with the assigned media provider object. If that algorithm returns without aborting this one, then the load failed.
Failed with media provider: Reaching this step indicates that the media resource failed to load. Take pending play promises and queue a media element task given the media element to run the dedicated media source failure steps with the result.
Wait for the task queued by the previous step to have executed.
Return. The element won't attempt to load another resource until this algorithm is triggered again.
⌛ If the src
attribute's value is the empty string, then end the synchronous section, and jump
down to the failed with attribute step below.
⌛ Let urlRecord be the result of encoding-parsing a URL
given the src attribute's value, relative to the
media element's node document when the src attribute was last changed.
⌛ If urlRecord is not failure, then set the currentSrc attribute to the result of applying the URL serializer to urlRecord.
End the synchronous section, continuing the remaining steps in parallel.
If urlRecord is not failure, then run the resource fetch algorithm with urlRecord. If that algorithm returns without aborting this one, then the load failed.
Failed with attribute: Reaching this step indicates that the media resource failed to load or that urlRecord is failure. Take pending play promises and queue a media element task given the media element to run the dedicated media source failure steps with the result.
Wait for the task queued by the previous step to have executed.
Return. The element won't attempt to load another resource until this algorithm is triggered again.
⌛ Let pointer be a position defined by two adjacent nodes in the media element's child list, treating the start of the list (before the first child in the list, if any) and end of the list (after the last child in the list, if any) as nodes in their own right. One node is the node before pointer, and the other node is the node after pointer. Initially, let pointer be the position between the candidate node and the next node, if there are any, or the end of the list, if it is the last node.
As nodes are inserted, removed, and moved into the media element, pointer must be updated as follows:
Other changes don't affect pointer.
⌛ Process candidate: If candidate does not have a
src attribute, or if its src attribute's value is the empty string, then end the
synchronous section, and jump down to the failed with elements step
below.
⌛ If candidate has a media
attribute whose value does not match the
environment, then end the synchronous section, and jump down to the
failed with elements step below.
⌛ Let urlRecord be the result of encoding-parsing a URL
given candidate's src attribute's value,
relative to candidate's node document when the src attribute was last changed.
⌛ If urlRecord is failure, then end the synchronous section, and jump down to the failed with elements step below.
⌛ If candidate has a type attribute whose value, when parsed as a MIME
type (including any codecs described by the codecs parameter, for
types that define that parameter), represents a type that the user agent knows it cannot
render, then end the synchronous section, and jump down to the failed with elements step below.
⌛ Set the currentSrc attribute to
the result of applying the URL serializer to
urlRecord.
End the synchronous section, continuing the remaining steps in parallel.
Run the resource fetch algorithm with urlRecord. If that algorithm returns without aborting this one, then the load failed.
Failed with elements: Queue a media element task given the
media element to fire an event named