Miracast

Miracast is a peer-to-peer wireless screencasting standard formed via Wi-Fi Direct connections in a manner similar to Bluetooth. It enables wireless delivery of audio and video to or from desktops, tablets, mobile phones, and other devices. It allows users to, for example, echo display from a phone or tablet onto a TV, share a laptop screen with the conference room projector in real-time, and watch live programs from a home cable box on a tablet. Both the sending and receiving devices must support Miracast for the technology to work. However, to stream music and movies to a device, such as a TV, that does not support Miracast, adapters are available that plug into HDMI or USB ports.^[1]

Miracast allows a portable device or computer to send, securely, up to 1080p HD video and 5.1 surround sound (AAC and AC3 are optional codecs, mandated codec is linear pulse-code modulation — 16 bits 48 kHz 2 channels).^[2] The protocol uses a direct Wi-Fi connection between the two devices without involvement of a wireless router and cannot be used to stream to a router access point.^[3][4] It was created by the Wi-Fi Alliance.

Devices

The Wi-Fi Alliance maintains a current list of Miracast-certified devices, both source devices and display devices. The technology and certification is fairly new with the first devices being certified in September 2012. As of January 19, 2013, only just over 100 devices in total were certified.

Nvidia announced support for it in their Tegra 3 platform,^[5] and Freescale Semiconductor, Texas Instruments, Qualcomm, Marvell Technology Group and other chip vendors have also announced their plans to support it.^[6]

Both devices (the sender and the receiver) need to be Miracast certified for the technology to work. However, to stream music and movies to a non-certified device there will be Miracast adapters available that plug into HDMI or USB ports.^[7]

On 29 October 2012, Google announced that Android version 4.2 (updated version of Jelly Bean) will support the Miracast wireless display standard, and by default will have integrated features for it.^[8] As of January 8, 2013, the LG Nexus 4 and Sony's Xperia Z, ZL, T and V officially support the function,^[9][10] as does HTC One, Motorola in their Droid Maxx & Ultra flagships, and Samsung in its Galaxy S III and Galaxy Note II under the moniker AllShare Cast. The Galaxy S4 uses Samsung Link for its implementation.^[11] In October 2013, BlackBerry released it's 10.2 update to the existing line of BlackBerry 10 devices, which brings Miracast and Wi-Fi Direct support to the Z30, Q10 and Q5 models.

In April 2013, Rockchip unveiled a Miracast adapter powered by the RK2928.^[12]

Microsoft also added support for Miracast in Windows 8.1 (announced this in June 2013).^[13] This functionality first became available in the Windows 8.1 Preview, and is available on hardware with supported Miracast drivers from hardware (GPU) manufacturers such as those listed above.

On 28 July 2013, Google announced the availability of the Chromecast powered by a Marvell DE3005-A1, but despite the similarity in name and Google's early support of Miracast in Android, the Chromecast does not support Miracast at this time.

Advantages

The technology was promoted to work across devices, regardless of brand. Miracast devices negotiate settings for each connection, which simplifies the process for the users. In particular, it obviates having to worry about format or codec details.^[14] Miracast is "effectively a wireless HDMI cable, copying everything from one screen to another using the H.264 codec and its own digital rights management (DRM) layer emulating the HDMI system". The Wi-Fi Alliance suggested that Miracast could also be used by a set-top box wanting to stream content to a TV, or tablet.

Types of media streamed

Miracast can stream videos that are in 1080p, media with DRM such as DVDs, as well as protected premium content streaming, enabling devices to stream feature films and other copy-protected materials. This is accomplished by using a Wi-Fi version of the same trusted content mechanisms used on cable-based HDMI and DisplayPort connections.^[15]

Disadvantages

Miracast is limited to Wi-Fi Direct supported devices. Comparing to other IP-based screen mirroring applications such as Splashtop,^[16] MirrorOp,^[17] VNC and RDP, Miracast cannot run on all IP networks such as conventional Wi-Fi, wired Ethernet, HomePlug powerline networking and Internet, but those IP-based screen mirroring applications can run on Wi-Fi Direct. The Miracast standard also has "optional components" such as Wireless Multimedia Extensions (WMM). The use of optional components in "standards" often causes issues if one vendor supports the options components and another does not. Its reliance on Wi-Fi Direct also reduces the attractiveness of the technology in enterprise environment.

Latency

Certification does not mandate a maximum latency (i.e. the time between display of picture on the source and display of the mirrored image on the sync display).

Legacy device incompatibility

The Wi-Fi Alliance certified the Wi-Fi Direct protocol in October 2010, and the first smartphone to ship with Wi-Fi Direct was the Samsung Galaxy S II, released in February 2011. All new Android devices starting with Android 4.0x (Ice Cream Sandwich) support Wi-Fi Direct. Desktop PC hardware can be upgraded with new Wi-Fi-Direct-compatible hardware. Only embedded devices will not be able to be upgraded.^{[citation needed]}

OS support

Miracast support is built into Android 4.2 or later ^[18] and starting with Android 4.4, devices can be certified to the Wi-Fi Alliance Display Specification as Miracast compatible.^[19] Miracast is also built into BlackBerry 10.2 devices and Microsoft Windows 8.1^[20] although developers can implement Miracast on top of the built-in Wi-Fi Direct support in Windows 7 and Windows 8.^[21] Another way to support Miracast in Windows is with Intel's proprietary WiDi v3.5 or above. Apple supports its own AirPlay mirroring instead of Miracast on OS X.

Business

IHS iSuppli Research predicts annual shipments of Miracast-certified devices to exceed one billion units by 2016.^[22]

See also

• Screencast
• Digital Living Network Alliance (DLNA)
• AirPlay

References

External links

(English) Wi-Fi CERTIFIED Miracast™ : Extending the Wi-Fi experience to seamless video display (PDF) on wi-fi.org