Test tryout of latest Android/PC app mirroring feature (Phone Companion)

1. Tryout: Phone Companion
All copyright reserved

2. Setup Requirements Info
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• Both PC and Android device on same wireless network (not working with USB direct tethering)
• “Your Phone” app on Windows PC
• “Your Phone – Link to Windows” app on Android device
• Multiple apps in separate windows: On Samsung device only S20 and above, with OneUI
3.0, can support separate multiple app windows, also requires Windows Insider Preview
Build 20257+
• Phone screen cast in one window: Android 9.0 and selected devices (e.g. S10 with
OneUI2.5) + Windows 10 Oct’18 update would work
• Without phone screen cast (notification, msg, photo, call): Android 7.0 (e.g. Pixel 3+) +
Windows Apr’18 update would work

3. Features
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4. Feature: phone screen mirroring
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• Copy & Paste between PC and Android
• Work nicely with text and image wherever it is
accepted
• Drag and Drop between PC and Android
• Largely work: file from and to “Device/File”,
photo only from Device to PC
• Direct audio control in Your Phone app
• Video cast (non-protected content) to PC, but
experiencing issue with audio playing out on phone
• Pin App to Start/Taskbar
• Work nicely to allow direct app launching –
bring up phone screen-cast to connect to
Android device and launch the app on device

5. Feature: app cast in separate windows
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• It is reported that only works with OneUI3.0 & latest Windows Insider
Program build. Below results tested with S20+/OneUI3.0 + Windows 10
Build 270.1. Microsoft announcement - Announcing Windows 10 Insider
Preview Build 20257 | Windows Insider Blog
• Observations:
1. Phone screen mirror window can coexist with individual app windows
2. App windows doesn’t have phone status bar on top and doesn’t have
system navigation bar at the bottom, no soft keyboard popup for input
as well. It acts more like individual app window, instead of individual
screen cast windows
3. Apps run on a different display surface than primary phone display. It
doesn’t show on primary phone display concurrently. A popup dialog
will ask for PC/Phone switch if an app is launched on a display surface
it is not current on
4. Youtube video continue to play even not an in-focus window, same for
Spotify and web browser video playback. Protected content is
honored by screen blackout
5. Issue remains that audio always play out on phone – could be the test
setup issue or current implementation limitation, will try more
6. Copy/Paste between PC/Phone not working in this test setup

6. User Experience Observation: It is nice when it works
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1. The experience feels nice when it works (except using mouse to navigate touch app still is
awkward, especially the swipe up gesture), no need of pick up the phone.
2. However, the main challenge is the connection between PC and Android device
• Initial connection between PC/Anroid device not trouble free, but largely work out
• Calling tab relies on BT and upon re-connection (time out?) sometimes have to turn on/off
BT on either device to re-establish the connection.
• Screen mirroring sometimes need to re-establish the connection upon switching tab or
period of idle. Usually takes 4~12 secs to establish connection. Once the mirroring is up,
then app launch is relatively fast - mostly half ~ 1s, though some hiccup occasionally.
• The sync of app response between PC/Android device is fast with minimum delay on both
direction (operate on device, or operate on PC) – mostly hundreds of ms to half sec.
3. Note that the frame rate of screen mirroring is not optimal at this moment, certainly more at
30ish than 60ish level, could be related to hardware setup involved and the connection link
optimization

7. User Experience Observation: compare with alternative
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Connection App-Launch Operation-Sync Operation Mode
Your
Phone
About 4 ~ 12s About half ~ 1s
About x00+ms ~
half sec
Tab:
• Notification / Message / Photo /
Screen Mirroring / Call
• Require PC/Device on same LAN
ScrCpy
About
1.6s(USB) &
2.3s (Wifi)
About 0.65s
(Wifi)
About 0.35s
• Only Screen Mirroring
• Requires PC/Device on USB
tethering or on LAN
Connection setup time is the area of big difference observed. Could be due to the fact that ScrCpy
only do simple non-encypt screen casting.

8. Behind the Scene
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BT-HSP
Data-UDP Ctrl-TCP
• Connection Link: rely on MSFT account/cloud to link and establish the connection between PC/Device. Observe MSFT
cloud (thus WLAN) is critical for maintain device connection. Without it, Notification/Messaging/Photo/ScreenMirroring
complain and go on strike
• Feature Notification/Messaging/Photo:
• On Samsung device, connection link complains as soon as WLAN disconnected. On Pixel device, it doesn’t complain
and new notif/photo continue to sync even with WLAN disconnected
• On Samsung device, don’t see direct PC/Device traffic, but lots of SSL/TCP traffic between PC  cloud, and cloud 
Device. On Pixel device, lots of direct TCP traffic between PC  Device
• Reading: cloud helpful in coordinating more than 1-to-1 link and offer extra intelligence, but add extra delay and
pose potential privacy/security concern
• Feature Screen Mirroring: relying on WLAN for device link, not working when router WLAN disconnected
• Observe only UDP traffic between PC  Device. Control signal either in UDP or through PC  cloud  Device
• Feature Calling: not depending on WLAN, but not work when BT turned off. Reading: Observe use of BT-HSP profile, not
surprisingly active ongoing call causes visual lag of BT mouse response.

9. What Next?
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Windows 10
Android Apps
WSL => Windows
Subsystem for Android
VM
Technology
A Universal OS for App
https://www.windowscentral.com/windows-10-project-latte-android-
apps#:~:text=Project%20Latte%20aims%20to%20deliver%20a%20similar%20product%2C,Android%20apps%20to%20actually%20run%2C%20however.%20Volume%200%25
It is reported that ChromeOS
is working on a “Phone Hub”
feature that could offer similar
experience to “Your Phone”
https://www.androidpolice.com/2020/08/17/google-is-working-on-
better-integration-between-chrome-os-and-android-devices/

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