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Amazon Silk
Developer Guide

Media Handling

Amazon Silk supports a wide range of media types.

Topics

Images

In addition to all the expected image formats, Amazon Silk supports scalable vector graphics (SVG) both inline via the <svg> tag and externally using the <img>, <object>, and <embed> tags. For more information, see SVG Element.

Image Optimization

Though not specific to Amazon Silk, the following tips can help you optimize images for your web site.

  • Set the width and height attributes: It's usually a good idea to set the width and height attributes explicitly on images. Browsers use the width and height attributes to determine the amount of space that an image needs in the page layout. If these attributes are not set, or if they don't match the actual dimensions of the image, the browser may have to reflow the page, which can increase page load time.

  • Remove excess white space: If you want to add padding around an image, you're better off doing it with CSS than with extra white space around the image itself. Extra space in an image increases file size.

  • Use the right file format: Using the correct file format for a given color palette and use case can help you minimize file size. As a general rule, use GIF for animations, GIF or PNG-8 for flat graphics or where transparency is needed, and JPG or PNG for photos and colorful, detailed images.

  • Consider using an image optimizer: Image optimizers can reduce the size of image files. Available image optimization tools include TinyPNG and the Grunt imagemin plugin.

For more information on image optimization, see Optimizing web graphics.

Audio

Amazon Silk fully supports the HTML5 Audio Element, with playback occurring in the browser. The default controls are improved from earlier Fire devices, and Silk also supports custom controls; playback of multiple streams; and MP3, OGG, and WAV audio formats. JavaScript support is good, enabling, for example, algorithmic PCM Audio using data URIs.

Amazon Silk doesn’t support background audio, meaning that audio playback is paused when a tab loses focus.

Video

Amazon Silk supports the HTML5 video tag, and MP4 and WEBM video formats. Note that the audio encoding in video streams must be at most stereo. The Fire family of devices doesn’t support 5.1 audio.

Amazon Silk also supports the RTSP and HLS network protocols. For more information about media formats that the Android platform supports, see Android Supported Media Formats.

Graceful Degradation with the Video Element

It's usually a good idea to use Feature Detection for features and media formats that aren't supported by all browsers. To detect video support, you can also try a simpler solution: graceful degradation with the HTML5 video element, which doesn't require JavaScript. In the example below, the video element provides a built-in fallback structure that lets you easily deliver multiple video container formats.

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<video controls> <source src="video.mp4" type="video/mp4"> <source src="video.webm" type="video/webm"> </video>

The example tries to serve MP4 and then falls back to the WebM file. The browser will play the first compatible format. For more on graceful video degradation, see Video for Everybody; for more on HTML5 video, see Video Element.

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