Miracast is a wireless communications standard created by the Wi-Fi Alliance which is designed to transmit video and sound directly from devices (such as laptops, tablets, or smartphones) to display receivers (such as TVs, monitors, or projectors). It can roughly be described as "HDMI over Wi-Fi", replacing cables in favor of wireless.[1] The protocol is utilised in many devices and is used or branded under various names by different manufacturers, including Smart View[2][3] and AllShare Cast (by Samsung), SmartShare (by LG), screen mirroring (by Sony), Cast (in Windows 11), wireless display and screen casting.[4][5][6]
The Wi-Fi Alliance launched the Miracast certification program at the end of 2012.[7] Devices that are Miracast-certified can communicate with each other, regardless of manufacturer. Nvidia announced support in 2012 for their Tegra 3 platform,[8] and Freescale Semiconductor, Texas Instruments, Qualcomm, Marvell Technology Group and other chip vendors have also announced their plans to support the Miracast standard.[9][10]
In 2017, Wi-Fi Alliance stated Miracast as a use for Wi-Fi Direct.[11]
The Wi-Fi Alliance maintains a list of certified device models, which numbered over 6,700 as of 9 March 2017.[update][12]
Miracast is based on the peer-to-peer Wi-Fi Direct standard. It allows sending up to 1080p HD video (H.264 codec) and 5.1 surround sound (AAC and AC3 are optional codecs, mandated codec is linear pulse-code modulation – 16 bits 48 kHz 2 channels).[13] 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.[14][15][16][17]
| Version | Date | Remarks[18] |
|---|---|---|
| 1.0 | 2012-08-24 | Public release version |
| 1.1 | 2014-04-24 | Public release for HDCPv2.2 updates. |
| 2.0 | 2017-04-21 | Release 2 final version. |
| 2.1 | 2017-07-31 | Corrected heading errors in sections 4.3 and 4.4.
Miracast as a use for Wi-Fi Direct.[11] Miracast hardware now supports HD, FHD and 4K screen streaming. |
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.[19] 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.
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, Miracast adapters are available that plug into HDMI or USB ports.[20]
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.[21]
Mandatory: ITU-T H.264 (Advanced Video Coding [AVC]) for HD and Ultra HD video; supports several profiles in transcoding and non-transcoding modes, including Constrained Baseline Profile (CBP), at levels ranging from 3.1 to 5.2
Optional: ITU-T H.265 (High Efficiency Video Coding [HEVC]) for HD and Ultra HD video; supports several profiles in transcoding and non-transcoding modes, including Main Profile, Main 444, SCC-8 bit 444, Main 444 10, at levels ranging from 3.1 to 5.1
Mandated audio codec: Linear Pulse-Code Modulation (LPCM) 16 bits, 48 kHz sampling, 2 channels
Optional audio codecs, including:
Certification does not mandate a maximum latency (i.e. the time between the display of pictures on the source and display of the mirrored image on the sync display). Even with certification, it is possible an underpowered device will be constrained in performance or bandwidth. Also, as a certified hardware standard, Miracast device support is 100% OEM determined. A software, firmware or OS update doesn't grant Miracast on uncertified hardware, even if the minimum requirements are met. (ex: Apple MacBooks, even with compatible Intel Core processors and Wi-Fi support that would be able to do Miracast if they were using Windows, either natively or under BootCamp, are not supported.)
Miracast was a feature of Android 4.2 "Jelly Bean" of 2012, but it only lasted until Android 6.0 "Marshmallow" of 2015, when Google replaced it with the Google Cast protocol. Computerworld observed that "Miracast never quite caught on as a standard".[23]
A device's wireless network adapter must support Wi-Fi Direct and Virtual Wi-Fi for it to work with Miracast; generally most adapters built since 2013 should meet the criteria. In Windows computers this can be checked by looking at the adapter's NDIS version which must be 6.3 or above.[24] However Miracast support also depends on the software implementation by manufacturers.
Microsoft also added support for Miracast in Windows 8.1 (announced in June 2013)[25][26] and available on hardware with supported Miracast drivers from hardware (GPU) manufacturers. Windows 10 and Windows 11 support Miracast transmitting along with User Input Back Channel (UIBC) support to allow for human interface devices (touch screens, mouse, keyboard) abbreviated as HID, to also have wireless connectivity (provided the host hardware also supports this). The transmit feature is built-in from launch for all Miracast devices with no additional setup past using the WIN+K keystroke to pair with a compatible display sink (including Microsoft's own Wireless Display Adapter).
Since Windows 10 Version 2004 was released a user needs to add "Wireless Display" as a optional Windows add-in feature in the Settings app to have a device receive video as a Miracast display sink on compatible hardware (using the UWP-based "Connect" app).[27] Windows 11 has the "Connect" app only as an optional add-in since RTM launch. Windows 8.1 supports broadcasting/sending the screen via Miracast.[28] Developers can also implement Miracast on top of the built-in Wi-Fi Direct support in Windows 7 and Windows 8.[29] Another way to support Miracast in Windows is with Intel's proprietary WiDi (v3.5 or higher).
While Linux does not feature native support, several add-on software solutions exist.[30][31][32] In the GNOME ecosystem, the GNOME Network Displays application has allowed for Miracast screen sharing. As part of the 2023 Google Summer of Code, an effort to integrate this as a feature in the GNOME Settings was announced, which would mean functionality would be had out of the box with that desktop environment.[33]
Miracast support was built into stock Android as of version 4.2 (Android Jelly Bean)[34][35][36] - as of January 2013, the LG Nexus 4 and Sony's Xperia Z, ZL, T and V officially supported the function,[37] as did HTC One, Motorola in their Droid Maxx and Droid Ultra flagships, and Samsung in its Galaxy S III and Galaxy Note II under the moniker AllShare Cast.[38] The Galaxy S4 uses Samsung Link for its implementation.[39] Some devices such as the Nexus 7 don't support it due to hardware limitations.[40]
Since Android 6.0 Marshmallow released in 2015, Google dropped[23] Miracast support in favor of their own proprietary Google Cast protocol[23] which was introduced with their Chromecast device.[41] Despite this there are third-party Miracast apps for Android available.[42] Some device manufacturers have added Miracast support through their customized versions of Android (for example: Smart View on Samsung's One UI, Cast on Xiaomi's MIUI, Screencast on Oppo's ColorOS, Wireless Projection on Huawei's EMUI, HTC Sense, LG UX, Asus ZenUI, Sony Xperia devices, OnePlus's OxygenOS etc.).[43] The performance and quality of the streamed video is dependent on the device's hardware.
Nokia devices, which ran a near-stock version of Android, originally did not support Miracast. However, Nokia 7 Plus, 8, 8 Sirocco, and 8.1 smartphones that have been upgraded to Android 9 or 10 are able to support Miracast, after enabling Wireless Display Certification in Developer Options. Devices such as Nokia 2.3, 2.4, 3.4, 5.4, and 8.3 5G have Miracast support enabled by default.[44] The same option is present to stock Android as well, with Google describing it as based on the "Wi-Fi Alliance Wi-Fi Display Specification",[45] but it tends to be useless as Miracast code was removed.[46]
Miracast is also built into Windows Phone 8.1.[28]
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.[47]
As of April 2016,[update] the Ubuntu Touch-powered Meizu Pro 5 supported Miracast in OTA-11.[48]
The Roku streaming stick and Roku TV started providing support for Miracast starting October 2014.[49] On 23 September 2014, Microsoft announced the Microsoft Wireless Display Adaptor, a USB-powered HDMI dongle for high definition televisions.[50][51] Actiontec Electronics also supports Miracast with its line of ScreenBeam products.[52]
In 2019, the Xbox One gained Miracast support using the optional downloadable Wireless Display app.[5] Also in 2019 the Amazon Fire TV Stick 4K gained Miracast support.[53]
