This document summarizes several wireless screen mirroring and streaming protocols including Apple AirPlay, Miracast/WiDi, Chromecast, and DIAL. It provides details on discovery methods, media protocols, codec and container support, commercial implementations, and software for creating Chromecast clones. Requirements for hacking AirPlay to remove DRM restrictions are also outlined.

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

7. 7

8. 8

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10. 10

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

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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/