ReferenceDisplay

media-poster

Poster image component that displays a thumbnail until video playback starts

Import

import '@videojs/html/ui/poster';

Anatomy

<media-poster>
  <img alt="" />
</media-poster>

Behavior

The poster shows before playback starts. Once the user plays or seeks, it hides; pausing does not bring it back. Loading a new source shows it again.

The <img> child is optional. Leave it out and <media-poster> draws one of its own in its shadow DOM.

You can set the poster URL on the player. This is useful when you want to change the poster from inside a skin, or keep all your media metadata in one place:

<video-player poster="poster.jpg"></video-player>

Supply your own image

The component fills in a source only when you leave one out. srcset, sizes, loading, <picture>, and framework image components all stay available.

<media-poster> draws a fallback image in its shadow DOM and fills in its src. Put an <img> inside it and the element uses yours instead, filling in its src the same way:

<media-poster>
  <img alt="" />
</media-poster>

Give that image a src, a srcset, or <source> candidates and it is yours; the component leaves it alone:

<media-poster>
  <img src="poster.jpg" srcset="poster-480.jpg 480w, poster-1080.jpg 1080w" alt="Keynote speaker" />
</media-poster>

Inside a skin, slot your image instead. The skin carries a plain one that yours replaces:

<video-skin>
  <video src="video.mp4" playsinline></video>
  <img slot="poster" src="poster.jpg" alt="Keynote speaker" />
</video-skin>

A skin can only style an <img> you slot directly. Wrap one in a <picture> or a framework component and its sizing is yours.

Styling

Attribute	Values	Description
`data-visible`	Present / absent	Present before playback starts
`data-loading`	Present / absent	Present while the image is fetching
`data-loaded`	Present / absent	Present once the image has loaded
`data-error`	Present / absent	Present when the image failed

The three load attributes track the image on screen, including one you supplied yourself.

media-poster:not([data-visible]) {
  opacity: 0;
}

The image the element draws is exposed as a part. An image you supply is an ordinary child, so style it as a descendant:

media-poster::part(image),
media-poster img {
  object-fit: cover;
}

From inside a skin’s shadow root, an image slotted from outside needs ::slotted(img) as well.

Accessibility

Unlike the native <video poster> attribute, this component lets you describe the poster for screen readers.

The image is decorative by default (alt=""), since a URL says nothing about what the image shows. When the poster carries meaning, say so:

<media-poster>
  <img src="poster.jpg" alt="Keynote speaker at a conference" />
</media-poster>

Whether a poster is informative or decorative is your judgment, per the WAI guidelines.

Examples

Basic Usage

Play Pause

<!-- TODO: add a captions track to the demo. -->
<video-player class="video-player" poster="https://image.mux.com/BV3YZtogl89mg9VcNBhhnHm02Y34zI1nlMuMQfAbl3dM/thumbnail.jpg">
  <media-container>
    <video src="https://stream.mux.com/BV3YZtogl89mg9VcNBhhnHm02Y34zI1nlMuMQfAbl3dM/highest.mp4" playsinline></video>

    <media-poster class="media-poster">
      <img alt="" />
    </media-poster>

    <media-play-button class="media-play-button">
      <span class="paused">Play</span>
      <span class="playing">Pause</span>
    </media-play-button>
  </media-container>
</video-player>

.video-player media-container {
  position: relative;
  display: block;
}

.video-player media-container video {
  width: 100%;
}

.media-poster {
  position: absolute;
  inset: 0;
  pointer-events: none;
  transition: opacity 0.25s;
}

.media-poster:not([data-visible]) {
  opacity: 0;
}

.media-poster img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media-play-button {
  position: absolute;
  bottom: 10px;
  left: 10px;
  padding-block: 8px;
  padding-inline: 16px;
  color: black;
  cursor: pointer;
  background: rgba(255, 255, 255, 0.75);
  border: 1px solid rgba(255, 255, 255, 0.25);
  border-radius: 9999px;
  backdrop-filter: blur(10px);
}

.media-play-button .paused,
.media-play-button .playing {
  display: none;
}

.media-play-button[data-paused] .paused {
  display: inline;
}

.media-play-button:not([data-paused]) .playing {
  display: inline;
}

import '@videojs/html/video/player';
import '@videojs/html/ui/container';
import '@videojs/html/ui/play-button';
import '@videojs/html/ui/poster';

API Reference

media-poster

<media-poster> — sets src on a poster image it does not own.

The image is a child, as in <picture>, but sourcing runs the other way around: <picture> treats the src on its <img> as the fallback, while here an image with no source of its own is the one this element fills in. Give the child a src, a srcset, or <source> candidates and it is yours, left alone.

Left empty, the element draws an image of its own in its shadow root. Supply one as a child to describe it or wrap it: <media-poster><img alt="Keynote speaker"></media-poster>. Inside a skin, an <img slot="poster"> of yours replaces the one the skin carries.

State

State is reflected as data attributes for CSS styling.

Property	Type	Details
`visible`	`boolean`
Description Whether the poster should be shown, which it is until playback starts.
`src`	`string`
Description Resolved poster URL, empty when nothing supplied one.
`loading`	`boolean`
Description Whether the poster image is fetching.
`loaded`	`boolean`
Description Whether the poster image has decoded.
`error`	`boolean`
Description Whether the poster image failed.

Data attributes

Attribute	Description
`data-visible`	Present until playback starts.
`data-loading`	Present while the poster image is fetching.
`data-loaded`	Present once the poster image has decoded.
`data-error`	Present when the poster image failed.