While cloud gaming opens new business opportunity, it also poses tremendous
challenges as the Internet only provides best-effort service and gamers are hard to
please. Although researchers have various ideas to improve cloud gaming systems,
existing cloud gaming systems are closed and proprietary, and cannot be used to
evaluate these ideas. We present GamingAnywhere, the first open-source cloud gaming system,
which is extensible, portable, and configurable. GamingAnywhere may be used by: (i)
researchers and engineers to implement and test their new ideas, (ii) service
providers to develop cloud gaming services, and (iii) gamers to set up private cloud
gaming systems. Details on GamingAnywhere are given in this paper. We firmly believe GamingAnywhere will
stimulate future studies on cloud gaming and real-time interactive distributed
systems.
Categories and Subject Descriptors: H.5 [Information Systems Applications]: Multimedia Information Systems
Keywords: Remote gaming; performance evaluation
1 Motivation
Computer games have become very popular, e.g., gamers spent 24.75
billion USD on computer games, hardware, and accessories in
2011 [6]. Traditionally, computer games are delivered
either in boxes or via Internet downloads. Gamers have to
install the computer games on physical machines to play them. The
installation process becomes extremely tedious because some games
are complicated and the computer hardware and system software are
fragmented. Take Blizzard's Starcraft II as an example, it
may take more than an hour to install it on an Intel i5 PC, and another
hour to apply the online patches. Furthermore, gamers may find
their computers are not powerful enough to enable all the visual
effects yet achieving high frame rates. Hence, gamers have to
repeatedly upgrade their computers so as to play the latest
computer games.
Cloud gaming is an alternative way to deliver high-quality gaming
experience and opens new business opportunity [13]. In a
cloud gaming system, computer games run on powerful cloud servers,
while gamers interact with the games via networked thin clients.
The thin clients are light-weight and can be ported to
resource-constrained platforms, such as mobile devices and TV
set-top boxes.
Figure 1 illustrates a sample cloud gaming service, in
which game servers stream game screens to thin clients, and thin clients
send gameplay controls, such as keystrokes and mouse movements, back to game servers.
With cloud gaming, gamers can play the latest
computer games anywhere and anytime, while game developers can
optimize their games for a specific server configuration. The huge
potential of cloud gaming has been recognized by the game
industry: (i) a market report predicts that cloud gaming market
will increase 9 times between 2011 and 2017 [4] and (ii)
several cloud gaming startups were recently acquired by leading
game developers [3,5].
Figure 1: A cloud gaming service based on GamingAnywhere.
Although cloud gaming is a promising direction for the game
industry, achieving good gaming experience without excessive
hardware investment is a tough challenge. This is because gamers are
hard to please, as they concurrently demand for high
responsiveness and high video quality, but do not want to pay too
much. Therefore, service providers have to not only design such
systems to meet gamers' needs but also take efficiency, error
resiliency, scalability, and resource allocation into
considerations. This renders the design and implementation of
cloud gaming systems extremely challenging. Indeed, while
real-time video streaming seems to be a mature technology at
the first glance, cloud gaming systems have to execute games, handle
gamers' inputs, and perform screen rendering, capturing, encoding,
packetizing, transmitting, decoding, and displaying in real time,
and thus are much more difficult to optimize.
Fortunately, many system researchers have new ideas to improve cloud gaming
experience for gamers, and reduce capital expenditure (CAPEX) and operational
expenditure (OPEX) for service providers. However, all the existing cloud gaming
platforms [12,14,7] are closed and proprietary, which prevent the
researchers from testing their ideas on real cloud gaming systems. Therefore, the
new ideas were either only tested using simulators/emulators, or, worse, never
evaluated and published. Without actual experiments, it is harder for new research
ideas on improving cloud gaming (or real-time interactive distributed systems) to be
transferred to the industry.
To better bridge the research community and the game/software industry, we initiate
GamingAnywhere, which is the first open-source cloud gaming testbed. While in its infancy, we
hope GamingAnywhere could gather enough attentions, and quickly grow into a community with
critical mass, just like OpenFlow [11], which shares the same motivation
with GamingAnywhere in a different research area.
The design philosophy of GamingAnywhere includes:
Extensibility: GamingAnywhere adopts a modularized design. For example,
platform-dependent components such as audio and video capturing and
platform-independent components such as codecs and network protocols can be easily
modified or replaced.
Portability: Gamers may use devices with heterogeneous architectures to
access GamingAnywhere, and thus it is important to port GamingAnywhere to as many platforms as possible.
Table 1 summarizes the supported platforms as of July 2013. New platforms
can be easily supported by replacing the platform-dependent components in GamingAnywhere.
Configurability: System researchers may conduct experiments with
diverse system parameters. A large number of built-in audio and video codecs are
supported by GamingAnywhere. In addition, GamingAnywhere exposes all available configurations to gamers
so that it is possible to try out the best combinations of parameters by simply
editing a text-based configuration file for various usage scenarios.
Openness: GamingAnywhere is publicly available at
http://gaminganywhere.org [8]. Researchers are free to
use and modify GamingAnywhere in academic research as long as the open-source license terms
are followed.
Table 1: Current supported platforms
Program
Windows
Linux
Mac OS X
Server
Windows 7+
Supported
No audio support
Client
Windows XP+
Supported
Supported
2 Target Users
GamingAnywhere is designed for three types of users. First, researchers and engineers may use
GamingAnywhere to evaluate their new ideas without re-implementing the irrelevant software
components. This will allow many new ideas to be tested in real testbeds and
deployed in fields. Second, cloud gaming service providers may develop a cloud
gaming front-end for gamers to choose the desired games, and integrate their
front-end with GamingAnywhere. Compared to developing a brand new cloud gaming system from
scratch, adopting GamingAnywhere largely reduces the time to market of new services. Third,
gamers may set up GamingAnywhere on their powerful home PCs, and enjoy high-quality gaming
experiences using thin clients via a LAN or the Internet.
To reach wider audience, GamingAnywhere is written in C/C++ and it leverages several popular
open-source libraries such as ffmpeg and libSDL. Detailed designs and
implementations can be found in Huang et al. [10]. We also hope users
contributing to this project by installing and playing with the system, providing
comments and suggestions, sharing game configurations, and even submitting patches
via the forum or public respositories.
3 Directory Structure
GamingAnywhere is released with two types of software packs: all-in-one and
pre-compiled binary packs [8]. The all-in-one pack includes
GamingAnywhere source codes, third-party library source code, pre-compiled binaries, while a
pre-compiled binary pack such as the bin.win32 pack includes only pre-compiled
binaries for running the software on a certain platform.
In any case, users can always build their own binaries that match their environments
from scratch.
There are six subdirectories upon uncompressing the all-in-one pack; their
descriptions are given below:
bin/: Contains all the required run-time files, including the
executables, shared objects, modules, fonts, and configuration files.
ga/: Source codes of GamingAnywhere, which is divided into four
parts: core, module, server, and client.
deps.posix/: Dependencies for POSIX platforms, including libraries and
headers. GamingAnywhere supports two POSIX platforms: Linux and Mac OS X. This subdirectory is
empty by default, as the files in this subdirectory are supposed to be built from
the sources in deps.src.
deps.win32/: Dependencies for Win32 platform, including libraries and
headers. This subdirectory is also empty by default, and the files in this
subdirectory will be installed from the third-party packages in
deps.pkg.win32.
deps.src/: Source files of the dependent third-party
packages. You will need these files to build dependencies, which
is mandatory for POSIX platforms.
deps.pkg.win32/: Pre-built dependencies for Win32 platform. You can
install all the dependencies for Win32 by running install.cmd in this
subdirectory. The dependencies are installed into the deps.win32 subdirectory
by default.
Figure 2: A demonstration of GamingAnywhere system. There are four devices in the
photo. One game server (the left-hand side laptop) and three game clients (a
MacBook, an Android phone, and an iPad 2). † LEGO Batman software
is copyrighted by Traveller's Tales Games Publishing Ltd.
4 Setup
GamingAnywhere can be installed by simply uncompressing the software packs, with or without
the source code. If the all-in-one software pack is downloaded, the complete
GamingAnywhere system can be compiled from scratch. One exception is the dependent Windows
libraries: because building them can be tricky, we include the pre-built Win32
libraries in the software packs.
We briefly describe how to build GamingAnywhere binaries below. GamingAnywhere consists of three
binaries: (i) ga-client, which is the thin client, (ii)
ga-server-periodic, which periodically captures the desktop or a window as the game
screen, and (iii) ga-server-event-driven, which directly hooks into the game
executables to capture game screens.
POSIX. To build GamingAnywhere on POSIX platforms (i.e., Linux and Mac OS X), please
make sure g++, pkg-config, libX11, libXext, libXtst,
libfreetype6, and libasound2 are installed. In addition,
libgl1-mesa, libglu1-mesa, and libpulse are required on
Linux. You must install both binaries and development files for the above packages.
Next, the following instructions are recommended:
Edit the env-setup script and point GADEPS to the absolute path of
gaminganywhere/deps.posix/.
Load environment variables from env-setup by using the . or
source commands.
Build dependencies using make under deps.src/.
Build GamingAnywhere using make all under ga/.
Install GamingAnywhere using make install command under ga/. All the
generated binaries will be copied into bin/.
Windows. To build GamingAnywhere on Microsoft Windows, please install Visual Studio
(C++) 2010, Windows SDK, and DirectX SDK. Then, follow the instructions:
Install dependencies by running install.cmd under deps.pkg.win32.
Install DirectX SDK into C:Microsoft DirectX SDK. If you install it at a different location, please modify the SDK paths in gamodulevsource-desktopNMakefile.d3d and gaserverevent-drivenNMakefile.
Launch Visual C++ command line prompt.
Build GamingAnywhere by running nmake /f NMakefile all command under ga.
Install GamingAnywhere by running nmake /f NMakefile install
command under ga. All the generated binaries
will be copied into bin.
5 Execution
This section explains how to run GamingAnywhere servers and client. Before running the
binaries, please check the following prerequisites. On POSIX, please add
deps.posix/lib to the system-wide ld.so search path. Moreover, modify
bin/config/common/server-common.conf to ensure that display is set to to an
X-Window desktop with the XTEST extension enabled. The X-Window desktop can be a
VNC or Xvfb desktop. On Windows, copy deps.win32
bin*.dll to the same directory of GamingAnywhere binaries (i.e.,
bin) or a directory in the system-wide DLL search path.
We give examples on how to run GamingAnywhere servers and client
using DirectX SDK samples on Windows.
• Run the periodic capture server. To stream a game window
to the client, launch the game first and then use the following command:
ga-server-periodic configserver.d3dex.conf.
The server configuration file sets either the find-window-name or
find-window-class option to specify the title and the class name, respectively, of
the game window to be streamed. Then, ga-server-periodic moves the specified
window to the upper-left corner of the desktop, and starts capturing the images of
the specified window periodically. Gamers should avoid moving the window manually as
it may affect the mouse cursor functionality.
If you do not know the window title or the class name, you can
find the information for a window by using the Spy++ tool
and the xwininfo tool on Windows and Linux, respectively.
• Run the event-driven server.
Rather than capturing a game's window periodically, GamingAnywhere provides another sample
server which is able to capture the game window each time right after the game
updates its screen. Please use the following command: ga-server-event-driven
configserver.d3dex.conf. ga-server-event-driven launches the
game executable specified by the game-dir and game-exe options in the
configuration file; that is why each game has its own configuration file.
• Run the client. The GamingAnywhere thin client can be run by
ga-client configclient.abs.conf rtsp://192.168.1.1:8554/desktop,
where the server IP address is 192.168.1.1; by default GamingAnywhere uses TCP port 8554 for
RTSP streams and TCP/UDP port 8555 for control messages. The client.abs.conf
is a sample configuration which enables the absolute mouse cursor positioning. In
contrast, client.rel.conf employs the relative mouse cursor positioning. The
choice of either configuration files is game-dependent, as different games use
different mechanisms for mouse position sensing and management.
6 Demo
Figure 2 shows a GamingAnywhere testbed in our lab. In this figure, the laptop
on the left-hand side runs the LEGO Batman game with GamingAnywhere event-driven server (i.e.,
ga-server-event-driven). The MacBook laptop on the right-hand side runs the
GamingAnywhere client. Two additional clients also connect to the server at the same time. One
client runs on an Android phone and another client runs on an iPad 2. Moreover, as
GamingAnywhere server delivers audio and video frames using the standard RTSP/RTP protocol, any
compatible RTSP/RTP players can be used to observe game plays.
We provide configuration files for several public-domain
games [8], such as Armagetron Advanced, Assault Cube, and
Neverball, so that gamers can quickly experience GamingAnywhere. Notice that the server
configuration files are game-dependent, and therefore we provide a sample server
configuration for each game. To get the server configuration working, please
modify the game-dir and game-exe options in the configuration files to
point to the game executables.
Figure 3: Response delays of GamingAnywhere, compared to two commercial
systems, OnLive and StreamMyGame.
7 Performance Evaluation
Responsiveness is one of the most important factors affecting gaming
experience [2,9]. We define response delay to be the time
difference between a user issuing a command and the in-game action appearing on the
client. Cloud gaming systems have stringent response delay requirements, as gamers
may demand for less than 100 ms response delay for certain games [2]. We
adopt the measurement techniques proposed in [1] in order to compare the
performance of GamingAnywhere against two commercial cloud gaming systems:
OnLive [12] and StreamMyGame (SMG) [14].
The response delay consists of two components: (i) processing delay, which is the
time required for the server to receive and process a gamer's command, and to encode
and transmit the corresponding frame to the client and (ii) playout delay, which is
the time required by the client to receive, decode, and render a frame on the
display. We do not report network delay in our measurement studies as it is not
controllable by the cloud gaming systems. Figure 3 summarizes the
processing delay (at server) and the playout delay (at client) measured under 3
games and 3 cloud gaming systems. We note that the playout delay is small, ≤ 31
ms for all games and systems. Moreover, GamingAnywhere achieves much shorter processing delay
( ≤ 34 ms), while OnLive and SMG suffer from up to 191 and 364 ms processing
delay. Considering the 100 ms requirement suggested by Claypool and
Claypool [2], GamingAnywhere works well when the network delay is < 50 ms, which is
fairly achievable, e.g., a GamingAnywhere server running at Los Angeles can serve a client at
as far as Oklahoma City. Due to the space limitations, detailed evaluation results
on GamingAnywhere can also be found in Huang et al. [10].
8 Conclusion
In this paper, we have presented GamingAnywhere, the first open-source cloud gaming system.
Different from closed and proprietary cloud gaming systems, GamingAnywhere allows researchers
and engineers to quickly explore their new ideas on how to improve gamers'
experience and increase service providers' revenue. Furthermore, GamingAnywhere is also
designed to be extensible, portable, and configurable, and thus can be adopted in
various usage scenarios, e.g., service providers may use GamingAnywhere to build up cloud
gaming services, and gamers may use GamingAnywhere to set up private cloud gaming systems. We
hope GamingAnywhere can become the cornerstone for multimedia research community to build and
evaluate many cloud gaming and real-time interactive distributed systems in the
future.
