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Screencasting

Rex Tsaichihchun@kalug.linux.org.tw

http://nutsfactory.net/H4 @ MR Brown

2013-08-29(2013-09-01 updated)

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Screen mirroring solutions

● AirPlay● mirroring standard for iOS.

● Miracast/WiDi● RTP/RTSP

● Chromecast● DIAL● WebRTC

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Apple AirPlay

● Wireless Media Streaming / Screen Mirroring Protocol for iOS● Discovery – Bonjour / zeroconf

● AirPlay service / RAOP (Remote Audio Output Protocol)● FairPlay for protect screen content and encrypted● UDP-based, based on RTSP● Codec - Apple Lossless codec with 44100 Hz and 2 channels

and H264● Proprietary protocol, only license audio-streaming to 3rd

partyies

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Requirement for hacks

● Understand FairPlay / DRM for screen protection ● FairPlay DRM initiation - ‘/fp-setup’ ● Video steaming encryption

● AirTunes/AirPlay private/public RSA keys● Implement the AirPlay receiver server

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Commerical products ofAirPlay mirroring

● James Laird reverse-engineered and released the private key

● VMLite rPlay for Raspberry Pi and Windows– http://www.youtube.com/watch?v=aviPOINM6Bk

● Electroniccolor - http://v.youku.com/v_show/id_XNTgwMjQzMTk2.html

AirParrot - http://www.airsquirrels.com/airparrot/● AirServer - http://www.airserver.com/● Hacksugar: Live AirPlay mirroring to Mac from iOS |

TUAW - The Unofficial Apple Weblog– http://www.tuaw.com/2012/02/08/hacksugar-live-airplay-mirroring-to-mac/

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Micrast/Wireless Display

● Discovery - WiFi Direct (Layer 2 protocol)● Media Protocol

● RTP● RTSP

● Available ● Android 4.2● Windows client available from Intel● Built-in in Windows 8.1

● Wi-Fi Display Technical Specification 199USD

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AOSP Miracast Sink

● Android 4.2

● https://github.com/kensuke/How-to-Miracast-on-AOSP/wiki

● https://github.com/kensuke/

● Demo - http://www.youtube.com/watch?v=KNEmaIr3FEg

● Possible to port this feature to Android dongle like mk802

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Chromecast

● DIscovery And Launch http://www.dial-multiscreen.org/● Based on UpnP & REST

● WebRTC http://www.webrtc.org/● Support applications

● YouTube● Netflix● Google Play Music● Google Play Movies & TV

● “Google Cast” Browser plugin available for Windows, Mac OS, Linux. https://chrome.google.com/webstore/detail/google-cast/boadgeojelhgndaghljhdicfkmllpafd

● Bootloader is hacked http://wiki.gtvhacker.com/index.php/Google_Chromecast#Bootloader_Exploit_Package

●

Does not work in AP Isolation mode https://support.google.com/chromecast/answer/3213084?hl=en

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Supported Media Types

● Video codecs: H.264 High Profile Level 4.1, 4.2 and 5, VP8

● Audio decoding: HE-AAC, LC-AAC, CELT/OPUS, MP3

● Containers: MP4/CENC, WebM, MPEG-DASH, SmoothStreaming

● Level 1 DRM support: Widevine, Playready

https://developers.google.com/cast/supported_media_types

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Chromecast clone Software

● SINK (Server)● CheapCast - https://github.com/mauimauer/cheapcast

– Supported Applications● ChromeCast● YouTube● PlayMovies● GoogleMusic● GoogleCastSampleApp● GoogleCastPlayer● Fling● TicTacToe

– Unstable, Android's WebView does not work well on old device like mk802.

● SOURCE (Clients)● AirCast ● RemoteCast

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References● Unofficial AirPlay Protocol Specification

http://nto.github.io/AirPlay.html

● Wi-Fi Display Technical Specification v1.0.0 http://www.wi-fi.org/knowledge-center/published-specifications

● Stream Laptop Content over HDTV with Intel® Wireless Display https://www-ssl.intel.com/content/www/us/en/architecture-and-technology/intel-wireless-display.html

● https://www.wi-fi.org/sites/default/files/uploads/wp_Miracast_Industry_20120919.pdf

● DIAL-2ndScreenProtocol-1.6.4.pdf http://www.dial-multiscreen.org/dial-protocol-specification

● Google Cast API https://developers.google.com/cast/