The document discusses new features and enhancements to LINE Group Call, a free audio/video group calling service. Key points include: 1. LINE Group Call supports up to 200 participants in a single call across iOS, Android, Windows, and Mac platforms. It uses a centralized server architecture to handle large-scale calls with low server costs. 2. Advanced voice quality enhancement technologies like echo cancellation and noise reduction help improve call audio quality. Extensive testing and tuning is done to optimize the service for different devices. 3. An upcoming new feature is video group calling, which will allow up to 200 participants with 4-10 videos displayed simultaneously and full screen viewing of a single participant. 4.

2. 1 LINE Group Call
2 Popcorn Buzz
3 Group Call Technologies
4 New Features

3. 1 LINE Group Call
2 Popcorn Buzz
3 Group Call Technologies
4 New Features

4. LINE Group Call
L a u n c h e d o n M a r c h 2 0 1 6
F r e e w h e n e v e r , w h e r e v e r !
F r e e g r o u p a u d i o c a l l s w h e n e v e r , w h e r e v e r
E a s y t o u s e
S t a r t g r o u p c a l l s w i t h j u s t o n e t a p f r o m c h a t s w i t h
m u l t i p l e p e o p l e
U p t o 2 0 0
T a l k w i t h u p t o 2 0 0 p e o p l e i n a s i n g l e g r o u p c a l l

5. LINE Group Call in Twitter

6. 1 LINE Group Call
2 Popcorn Buzz
3 Group Call Technologies
4 New Features

7. Popcorn Buzz
L a u n c h e d o n J u n e 2 0 1 5
O u r f i r s t g r o u p c a l l s e r v i c e
A g r o u p c a l l s e r v i c e l a u n c h e d a y e a r b e f o r e
L I N E G r o u p C a l l
U s e w i t h o u t L I N E
M a k e c a l l s w i t h o u t L I N E u s i n g t h e s t a n d a l o n e a p p
L o g i n a s a g u e s t o r u s e y o u r L I N E l o g i n c r e d e n t i a l s
E a s y t o i n v i t e
S e n d a n d a c c e p t i n v i t e s u s i n g U R L s
I n v i t e y o u r L I N E f r i e n d s w h e n y o u l o g i n w i t h y o u r
L I N E a c c o u n t
U p t o 2 0 0
T a l k w i t h u p t o 2 0 0 p e o p l e i n a s i n g l e g r o u p c a l l

8. Saudi Arabia Likes Popcorn Buzz
Ranked near the top of the App Store in Saudi Arabia during March
Still among the top 30 apps
We attribute the user increase to the accessibility of the app (guest login, URL invites)

9. 1 LINE Group Call
2 Popcorn Buzz
3 Group Call Technologies
4 New Features

10. iPhone
Android
iPad
Windows
Mac OSX
5% Mobile Network
L I N E G r o u p C a l l s u p p o r t s v a r i o u s p l a t f o r m s
i O S , A n d r o i d , W i n d o w s , M a c O S X
U s e r s o f L I N E G r o u p C a l l b y p l a t f o r m
- > 9 5 % o f G r o u p C a l l s m a d e o n m o b i l e d e v i c e s
T r a f f i c o n m o b i l e n e t w o r k s l e a d t o h i g h e r c o s t s
o n t h e p h o n e b i l l s o f u s e r s
T r a f f i c m u s t b e k e p t t o a m i n i m u m
67%
28%

11. Full Mesh End System Mixing Centralized Server
Low server costs
Network Models of Group Call
Increase in participants increases traffic
High performance clients (likely on a PC) act
as a mixing server
Number of participants limited due to the
limitations of the client where mixing is
performed
Group call ends if client performing mixing
disconnects
All clients send and receive media to and from
each other
Similar to P2P networking
Low server costs
Mixed on a central server
Increase in call participants doesn’t increase
traffic
Able to stably host large-scale calls
High server costs
For mobile services, keeping traffic at a minimum is key
LINE Group Call uses the “Centralized Server” method

12. LINE Group Call is used in about 200 countries
Global Service
Darker colors indicate higher group call usage

13. Role Based Layering
Scalable Server Architecture
Clusters are divided by role
The clusters in each layer are
horizontally scalable
LINE Talk Server
Voice Layer
LINE Group Call
Mix Server
LINE
Client
Request & Response
For Application
Voice
Voice Layer and Application Layer
The cluster that processes audio and the cluster that processes application functions are divided
Only have to develop a new application layer on top of Popcorn Buzz, saving development time for LINE Group Call
Front End Layer and Audio Mix Layer
The front end handling connection between the client and the network, and the server handling mixing are divided
Able to respond to the usage rates of each region more flexibly
LINE Group Call
Front End Server
Application Layer

14. Regional Distributed Server Architecture
Multi Regional IDC
JP: East Asia
SG: Middle Asia
DE: Europe, Africa, MENA
US: America
Front end servers selected based on proximity to user
The front end server from the IDC closest to the user is used in order to provide optimal network speeds
Audio mix server selected based on proximity to user who started group call
The audio mix server from the IDC closest to the user who started the group call is used
Dedicated line between front end server and audio mix server
If users in different regions are in the same group call, each user will connect to the closest front end server. If the front end server IDC
is different from the one handling audio mixing, a dedicated line is used to ensure network quality

15. Voice Quality Enhancement (VQE)
Technologies that solve these problems => Voice Quality Enhancement
・Acoustic Echo Cancellation
・Noise Cancellation
・Auto Gain Control
・Audio Volume Control
・And more..
Problems that make audio worse
Echo
The sound of your voice leaving the speaker and
going back into the mic, making you hear your
own voice
Noise
Unwanted sound from the caller’s surroundings
Echo
Near-End
Speech
Noise

16. Difficulty of VQE
Many devices use LINE Group Call
VQE is a highly complex technology to begin with…
The biggest hurdle is the fact that users use so many different devices
・Each device has speakers, mics, audio modules with differing characteristics
・For optimal quality, VQE tuning is required for each and every device
A p p r o x i m a t e l y 2 0 0 0 0 d e v i c e s u s e d

17. Tuning For High Quality
Superb quality testing environment
・Environment based on ITU-T P.341 testing room conditions
・Head and Torso Simulator (HATS) used for testing
Testing as many devices as possible
・Testing and tuning conducted on popular devices as well as devices reported to have problems
Cooperation with device manufacturers
・Both LINE and device manufacturers make a shared effort to fix reported problems

18. 1 LINE Group Call
2 Popcorn Buzz
3 Group Call Technologies
4 New Features

19. Video Group Call
C o m i n g S o o n !
E a s y t o u s e
S t a r t g r o u p c a l l s w i t h j u s t o n e t a p f r o m c h a t s
w i t h m u l t i p l e p e o p l e
U p t o 2 0 0
T a l k w i t h u p t o 2 0 0 p e o p l e i n a s i n g l e g r o u p c a l l
4 - 1 0 p e o p l e s i m u l t a n e o u s l y d i s p l a y e d o n s c r e e n
F u l l S c r e e n V i e w
H i g h l i g h t a s p e c i f i c u s e r w i t h t h e F u l l S c r e e n V i e w
m o d e f r o m G r i d V i e w

20. Variable Resolutions in Video Group Call
LINE
Video Group Call
Server
What can we do to transfer different resolutions effectively?
Resolution:
Full Screen
Resolution:
Quarter
Resolution:
Thumbnail

21. Multi-Layer Video Stream
Dynamic Resolution by Multi Layer
Upload with the following layers included
High quality + Medium quality + Low quality
For high quality,
High quality + Medium quality + Low quality
For medium quality,
Medium quality + Low quality
For low quality,
Low quality
Possible to display media in various resolutions from a single media stream without transcoding
-> Provide bitrates and resolutions optimized for the client environment with low server load
Source
H i g h R e s o l u t i o n L a y e r
M e d i u m R e s o l u t i o n L a y e r
L o w R e s o l u t i o n L a y e r
H i g h
R e s o l u t i o n
M e d i u m
R e s o l u t i o n
L o w
R e s o l u t i o n
Router