Screencasting

Transcript

1. 1 Screencasting Rex Tsai chihchun@kalug.linux.org.tw http://nutsfactory.net/ H4 @ MR Brown 2013-08-29 (2013-09-01 updated)
2. 2 Screen mirroring solutions • AirPlay • mirroring standard for iOS. • Miracast/WiDi • RTP/RTSP • Chromecast • DIAL • WebRTC
3. 3 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
4. 4 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
5. 5 Commerical products of AirPlay 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/
6. 6 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
11. 11 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
12. 12 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
13. 13 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
16. 16 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
17. 17 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/