Chromecast

Chromecast is a digital media player developed by Google. The device, a 2.83 in HDMI dongle, plays audio/video content on a high-definition display by directly streaming it via Wi-Fi from the Internet or a local network. Users select the media to play using Chromecast-enabled mobile apps and web apps. Alternatively, content can be mirrored from the Google Chrome web browser running on a personal computer, as well as from the screen of some Android devices. Chromecast was announced on July 24, 2013, and made available for purchase on the same day in the United States for US$35, along with a limited-time promotion for three free months of Netflix. The Google Cast SDK was released on February 3, 2014, allowing third parties to modify their software to work with Chromecast.

Features and operation
Measuring 2.83 in, Chromecast is a dongle that plugs into the HDMI port of a high-definition television or monitor, while the power is supplied by connecting the device's micro-USB port to an external power supply or a USB port. The device connects to the Internet through a Wi-Fi connection to the user's home network. Chromecast offers two methods to stream content to a television: the first employs Chromecast-enabled mobile apps and web apps; the second allows mirroring of most content displayed by the web browser Google Chrome running on a personal computer, as well as content displayed on some Android devices. In both cases, playback is initiated through the "cast" button on the controlling device. If the television's HDMI ports support the Consumer Electronics Control (CEC) feature, pressing the cast button will also result in the Chromecast automatically switching the television's active audio/video input using the CEC command "One Touch Playback".


 * The primary method of playing media on the device is through Chromecast-enabled mobile apps and web apps, which control program selection, playback, and volume. The Chromecast itself streams the media from the web within a local version of the Chrome browser, thus freeing the controlling device up for other tasks, such as answering a call or using another application, without disrupting playback. Mobile apps enabled for Chromecast are available for both Android 2.3+ and iOS 6.0+; web apps enabled for Chromecast are available on computers running Google Chrome (on Microsoft Windows 7+, Mac OS 10.7+, and Chrome OS for Chromebooks running Chrome 28+) through the installation of the "Cast Extension" in the browser. Streamed content can be Internet-based, as provided by specific apps, as well as resident on the controlling device. Apps that provide access to the latter include AllCast, Avia, and Plex.


 * Content can also be mirrored from a tab of the Chrome browser (with the Cast extension) on a personal computer or from the screen of some Android devices. In the case of "tab casting", the quality of the image depends on the processing power of the device and minimum system requirements apply to video streaming. Content that uses plug-ins, such as Silverlight and QuickTime, does not fully work, as the stream may lack sound or image. Google lists the feature as beta. Similarly, screen images mirrored from Android devices are typically degraded, reflecting the fact that video displayed on the smaller screens of tablets and smartphones is usually downscaled.

Several upcoming features for Chromecast were announced at Google I/O 2014. Users' controlling devices will no longer need to be connected to the same Wi-Fi network as the Chromecast to cast content. Instead, the controlling device can discover nearby Chromecasts by detecting ultrasonic sounds emitted by the television to which the Chromecast is connected; alternatively, the controlling device can be paired with the Chromecast over the web using a four-digit PIN code provided on screen. A new "Backdrop" feature will incorporate a user-personalized feed of content into the Chromecast's home/standby screen.

Hardware
Chromecast contains the Marvell 88DE3005 (Armada 1500-mini) system on a chip, which includes codecs for hardware decoding of the VP8 and H.264 video compression formats. Radio communication is handled by AzureWave NH–387 Wi-Fi which implements 802.11b/g/n (2.4 GHz). The device has 512 MB of Micron DDR3L RAM and 2 GB of flash storage. The model number H2G2-42 is likely a reference to the The Hitchhiker's Guide to the Galaxy abbreviation "H2G2"—in the novel, the number 42 is the "Answer to Life, the Universe, and Everything." The bundled power adapter bears the model number MST3K-US, likely a reference to Mystery Science Theater 3000.

Software development kit and compatible apps
At the time of Chromecast's launch, four compatible apps were available: YouTube and Netflix were supported as Android, iOS, and Chrome web apps; Google Play Music and Google Play Movies & TV were also supported, but originally only as Android apps.

The Google Cast software development kit (SDK), which gives developers a way of handling "second-screen interactions" and making their apps Chromecast enabled, was released as a preview version on July 24, 2013. Google advised interested developers to create and test Chromecast-enabled apps, but not distribute them until the company released the production version of the device's SDK. While that admonition remained in force, Chromecast-enabled applications for Hulu Plus and Pandora Radio were released in October 2013, and HBO GO in November. Jeff Lawrence, head of MediaMall Technologies (PlayOn), said that Google was giving "most favored developer" status to major streaming companies, a move he found understandable from Google's perspective, but frustrating to other developers given the lack of a concrete timeline. Google invited developers to a two-day hackathon on December 7 at Googleplex, its Mountain View headquarters, offering the opportunity to test drive the SDK's "upcoming release". The session attracted 40 developers from 30 companies and was followed by 10 additional apps, including Plex, Avia, and Realplayer Cloud.

Google opened the SDK to all developers on February 3, 2014. In its introductory documentation and video presentation, Google said the SDK worked with both Chromecast devices and other unnamed "cast receiver devices". Chromecast product manager Rish Chandra said that Google used the intervening time to improve the SDK's reliability and accommodate those developers who sought a quick and easy way to cast a photo to a television without a lot of coding. Google also made the SDK a part of the Google Play Services framework, thereby giving users access to new apps without having to update Android itself. Over time, many more applications have been updated to support Chromecast. At Google I/O 2014, the company announced that 6,000 registered developers were working on 10,000 Chromecast apps. Google's official list of compatible apps and platforms is available on the Chromecast website.

The development framework has two components: a sender app and a receiver app, both of which make use of APIs provided by the SDK.
 * The sender app is based on a vendor's existing Android or iOS mobile app, or desktop Web app, and provides users with content discovery and media controls, including the ability to select which device content is streamed. Under the hood, sender apps can detect receiver devices on the same local network, establish a secure channel, and exchange messages.
 * The receiver app is a Web app executing in a Chrome browser-like environment resident on the cast receiver device. Receiver apps of varying complexities can be developed depending on the variety of content formats the app can play. For example, a simple receiver app might just play HTML5 content, whereas custom receiver apps, which require more programming effort, can take a variety of streaming protocols, including MPEG-DASH, HTTP Live Streaming, and the Microsoft Smooth Streaming Protocol.

Device discovery protocols
Chromecast uses the mDNS (multicast Domain Name System) protocol to search for available devices on a Wi-Fi network. Chromecast previously used the DIAL (DIscovery And Launch) protocol, co-developed by Netflix and YouTube.

Operating system
At the introductory press conference, Hugo Barra, then Google's vice president of Android product management, said that Chromecast is "running a simplified version of Chrome OS." Subsequently, a team of hackers reported that the device is "more Android than ChromeOS" and appears to be adapted from software embedded in Google TV.

Google lists Chromecast operating system updates on the Chrome Releases blog. As with Chrome OS devices, Chromecast operating system updates are downloaded automatically without notification.

Release and promotion
Google made Chromecast available for purchase online in the US on July 24, 2013. To entice consumers, Google initially included a promotion for three months of access to Netflix at no cost with the purchase of a Chromecast. The device quickly sold out on Amazon.com, BestBuy.com, and the Google Play Store, and within 24 hours, the Netflix promotion was ended because of high demand. On October 19, 2013, the Chromecast mobile app was released outside of the US for the first time. On March 18, 2014, Google released the Chromecast to 11 new markets, including the UK, Germany, Canada, and more. In July 2014, to commemorate the one-year anniversary of the device's launch, Google announced it would offer their music streaming service, Google Play Music All Access, at no cost for 90 days to Chromecast owners who had not previously used All Access; the service normally costs US$9.99 per month.

Reception
Nilay Patel of The Verge gave the Chromecast an 8.5/10 score in his review, saying, "The Chromecast is basically an impulse purchase that just happens to be the simplest, cheapest, and best solution for getting a browser window on your TV." Speaking of the adapter's potential, he said, "it seems like the Chromecast might actually deliver on all that potential, but Google still has a lot of work to do." In particular, Patel pointed to Apple's AirPlay protocol as an example of an established competitor with many more features. TechCrunch's review of the device said, "Even with a bug or two rearing its head, the Chromecast is easily worth its $35 pricetag." Gizmodo gave the device a positive review, highlighting the ease of setup and sharing video. In comparing the device to competitors, the review said, "Chromecast isn't Google's version of Apple TV, and it's not trying to be... But Chromecast also costs a third of what those devices do, and has plenty of potential given that its SDK is just a few days old."

Michael Gorman of Engadget gave the Chromecast an 84/100 score, writing, "it's a platform that's likely to improve dramatically as more apps start to support the technology." In his comparing the Chromecast to competing devices, Gorman illustrated that it initially had support from fewer multimedia services, but because of its low price and ease of use, he concluded "we can wholeheartedly recommend the Chromecast for anyone who's been looking for an easy, unobtrusive way to put some brains into their dumb TV." David Pogue of The New York Times praised the device for its $35 retail price, saying, "It's already a fine price for what this gadget does, and it will seem better and better the more video apps are made to work with it." Pogue noted the limitations of the device's screen mirroring feature and said using only mobile devices as a remote control was not "especially graceful", but he called Chromecast the "smallest, cheapest, simplest way yet to add Internet to your TV".

In July 2014, Google announced that in the device's first year on sale, "millions" of units had sold and over 400 million casts had been made.