Miracast

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Miracast is a certification program of the Wi-Fi Alliance based on their Wifi-Display specification. It defines a protocol to connect an external monitor or TV to a device, and therefore can roughly be described as "HDMI over Wifi", replacing the cable from the computer to the display.[1]

It is peer-to-peer, and wireless, using a Wi-Fi Direct connection. It allows sending 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). The connection is created via WPS and therefore is secured with WPA2. IPv4 is used on the internet layer. On the transport layer, TCP or UDP are used. On the application layer, the stream is initiated and controlled via RTSP, RTP for the data transfer.[2][3][4][5] Adapters are available that plug into HDMI or USB ports that enable Non-Miracast devices to connect via Miracast.[6] The developer responsible for the implementation of Miracast in Linux does not recommend the standard as the technology is "horrible".[2]

Devices[edit]

The Wi-Fi Alliance maintains a current list of Miracast-certified devices, which features 3,438 devices as of February 2, 2015.

Nvidia announced support for it in their Tegra 3 platform,[7] and Freescale Semiconductor, Texas Instruments, Qualcomm, Marvell Technology Group and other chip vendors have also announced their plans to support it.[8]

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.[9]

On 29 October 2012, Google announced that Android version 4.2+ (from updated version of Jelly Bean) are supporting the Miracast wireless display standard, and by default have it integrated .[10]

As of January 8, 2013, the LG Nexus 4 and Sony's Xperia Z, ZL, T and V officially support the function,[11][12] 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.[13] In October 2013, BlackBerry released its 10.2.1 update to most of the existing BlackBerry 10 devices available at that time. As of March 2015, the BlackBerry Q10, Q5, Z30, and later models support Miracast streaming; the BlackBerry Z10 does not support Miracast, due to hardware limitations.[14]

In April 2013, Rockchip unveiled a Miracast adapter powered by the RK2928.[15]

Microsoft also added support for Miracast in Windows 8.1 (announced this in June 2013).[16] 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.

The WDTV Live Streaming Media Player added Miracast support with firmware version 2.02.32

The Amazon Fire TV Stick, which started shipping on 19 November 2014, also supports Miracast.

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.

Advantages[edit]

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.[17] 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[edit]

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.[18]

Disadvantages[edit]

Miracast is limited to Wi-Fi Direct supported devices. Comparing to other IP-based screen mirroring applications such as Splashtop,[19] MirrorOp,[20] VNC and RDP, Miracast cannot run on all IP networks such as conventional Wi-Fi, wired Ethernet, 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 environments.

The development of the support in Linux took 4 months, and the relevant developer originally recommended not to buy or use devices supporting Miracast. The following reasons were cited:[1][2]

  • the specification is only available on payment of a large amount of money.
  • hardware is barely available; in February 2014, the only working chip was Intel's 7260-WLAN-Chip.
  • The developer considers the technology "horrible". Filters are sent which define properties of the hardware, e.g. the screen resolution. This boils down to an enormous amount of data sent which makes its challenging to find the correct peering device. IPv4 including DHCP is used as internet protocol, not the new IPv6. To transfer contents the sender and receiver device should be done, but sometimes this happens spontaneously without a possibility to change it afterwards. The streaming is controlled via the RTSP. The disadvantage is that the receiver explicitly needs to request the data transfer from the sender - instead of the sender just starting the transfer.

Latency[edit]

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).

Device incompatibility[edit]

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[citation needed], 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]

There are serious incompatibilities between Miracast devices, i.e. being Miracast compatible does not mean devices can talk to each other. On the internet huge lists are collected with devices compatible to each other.[21][22][23]

OS support[edit]

Miracast support is built into Android 4.2 or later [24] and starting with Android 4.4, devices can be certified to the Wi-Fi Alliance Display Specification as Miracast compatible.[25] Miracast is also built into BlackBerry 10.2.1 devices and Microsoft Windows Phone 8.1 and Windows 8.1[26] although developers can implement Miracast on top of the built-in Wi-Fi Direct support in Windows 7 and Windows 8.[27] Another way to support Miracast in Windows is with Intel's proprietary WiDi v3.5 or above. Apple supports its own Peer-to-peer AirPlay instead of Miracast on OS X. For the Linux desktop there exists MiracleCast which provides early support for miracast but is not tied to that single protocol. A software based Miracast receiver for Windows 8.1, AirServer Universal was made available on October 31, 2014 by App Dynamic.

See also[edit]

References[edit]

  1. ^ a b On Wifi-Display, Democratic Republics and Miracles, Patrick Herrmann, on the development of Miraclecast, 2014-02-17.
  2. ^ a b c "Miracast unter Linux ist schrecklich", golem.de, 2014-02-02.
  3. ^ "Wi-Fi Certified Miracast : Extending the Wi-Fi experience to seamless video display" (PDF). Wi-fi.org. Retrieved 2013-10-17. 
  4. ^ Lutz, Zachary (2012-07-26). "NVIDIA throws support behind Miracast as wireless display standard". Engadget.com. Retrieved 2013-10-17. 
  5. ^ Brodkin, Jon (2012-07-10). "AirPlay for all? Miracast promises video streaming without the router". Ars Technica. Retrieved 2013-10-17. 
  6. ^ "NVIDIA Announces Compatibility with WiFi Display Miracast Specification". AnandTech. Retrieved 2013-10-17. 
  7. ^ "Nvidia supports Miracast". 
  8. ^ "Airplay for all?". 
  9. ^ Chacos, Brad (21 September 2012). "How Miracast Could Finally Make Your Smartphone Run Your Home Theater". Digital Trends. 
  10. ^ Android 4.2 adds official support for Miracast wireless display
  11. ^ "PSA: Nexus 7 and Nexus 10 do not support Miracast wireless display". Phandroid.com. 2012-11-19. Retrieved 2013-10-17. 
  12. ^ "Wi-Fi Miracast Screen Mirroring demoed on the Xperia T [Video]". Xperia Blog. Retrieved 2013-10-17. 
  13. ^ "Trying Samsung’s renewed application: Samsung Link". SamMobile. 2013-03-27. Retrieved 2013-10-17. 
  14. ^ "Miracast will not be available on the BlackBerry Z10, Wi-Fi Direct supported instead". CrackBerry. MobileNations. 14 Aug 2013. Retrieved 26 March 2015. 
  15. ^ "Rockchip Unveils RK3168 Dual Core Processor, Showcases $10 Miracast Adapter". Cnx-software.com. Retrieved 2013-10-17. 
  16. ^ "What’s New For The Enterprise In Windows 8.1". Blogs.windows.com. Retrieved 2013-10-17. 
  17. ^ Wagner, Kyle (19 September 2012). "What Is Miracast?". Gizmodo. 
  18. ^ Parrish, Kevin (19 September 2012). "Wi-Fi Alliance Announces First Miracast-Certified Devices". Tom's Hardware. 
  19. ^ "Splashtop is the #1 Remote Desktop and Application Access for Mobile Devices". Splashtop.com. Retrieved 2013-10-17. 
  20. ^ "MirrorOp". MirrorOp. Retrieved 2013-10-17. 
  21. ^ Hannes A. Czerulla, Sven Hansen: Miracast-Check in: c't. Hannover 2013,17, S.148. ISSN 0724-8679
  22. ^ How to Use Miracast and WiDi, tom's GUIDE, 2014-07-30.
  23. ^ List of compatible devices for the WD TV Live Hub Media Center, WD TV Live Streaming Media Player and WD TV Media Player, Western Digital e.g. collecting compatible devices, accessed 2014-12-26.
  24. ^ "Miracast: Everything to know about mirroring Android". CNET. 2013-09-24. Retrieved 2013-12-19. 
  25. ^ "Android Kitkat Overview". developer.android.com. 2013-10-31. Retrieved 2013-11-12. 
  26. ^ "Windows 8.1 on your big screen with Miracast". blogs.microsoft.com. 2013-11-12. Retrieved 2013-11-12. 
  27. ^ "DMR support for Wi-Fi Direct (WFD-01)". Msdn.microsoft.com. 2013-07-26. Retrieved 2013-10-17. 

External links[edit]