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The RDP specification for the AUDIO_INPUT channel requires that all audio be sent in packets of a specific size. Guacamole does correctly limit itself to sending packets of this size to the RDP server, but will send quite a few of these packets all at once if it has received more audio data than the RDP packet size. This is OK in principle (the Guacamole client should be able to send audio in packets of whatever size it chooses), but may overwhelm the software running within the RDP server if the amount of data received exceeds the available buffer space, resulting in dropped samples. As there is no way to know the size of the remote audio buffer, we need to instead ensure that audio is streamed as close to real time as possible, with each audio packet of N bytes not being sent until roughly the amount of time represented by those N bytes has elapsed since the last packet. This throttling ensures that software expecting to process audio in real time should never run out of buffer space. That said, if we never exceed the per-packet data rate and occasionally send a packet earlier than real time would dictate, unavoidable latency in sending/receiving audio data would accumulate over time. For example, if each audio packet represents 10ms of audio data, but we receive that audio packet 10.1ms after the previous packet, we need to adjust the timing of the next audio packet(s) to account for that additional 0.1ms. Simply waiting 10ms after sending each packet would cause that 0.1ms to accumulate each time it occurs, eventually resulting in noticable latency and finally running out of buffer space. Thus, these changes: 1. Leverage a flush thread and per-packet scheduling to ensure that each flushed audio packet does not exceed the equivalent real time rate. 2. Calculate the amount of additional latency from the amount of data received beyond the required packet size, and amortize scheduling corrections to account for that latency over the next several audio packets. This ensures that audio is streamed exactly as it is received if the audio matches the packet size of the RDP server, and audio that is received in a different size or varying sizes is buffered and throttled to keep things within the expectations of software running within the RDP server. |
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bin | ||
doc | ||
m4 | ||
src | ||
util | ||
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.gitignore | ||
configure.ac | ||
CONTRIBUTING | ||
Dockerfile | ||
LICENSE | ||
Makefile.am | ||
NOTICE | ||
README | ||
README-unit-testing.md |
------------------------------------------------------------ About this README ------------------------------------------------------------ This README is intended to provide quick and to-the-point documentation for technical users intending to compile parts of Apache Guacamole themselves. Source archives are available from the downloads section of the project website: http://guacamole.apache.org/ A full manual is available as well: http://guacamole.apache.org/doc/gug/ ------------------------------------------------------------ What is guacamole-server? ------------------------------------------------------------ The guacamole-server package is a set of software which forms the basis of the Guacamole stack. It consists of guacd, libguac, and several protocol support libraries. guacd is the Guacamole proxy daemon used by the Guacamole web application and framework. As JavaScript cannot handle binary protocols (like VNC and remote desktop) efficiently, a new text-based protocol was developed which would contain a common superset of the operations needed for efficient remote desktop access, but would be easy for JavaScript programs to process. guacd is the proxy which translates between arbitrary protocols and the Guacamole protocol. ------------------------------------------------------------ Required dependencies ------------------------------------------------------------ All software within guacamole-server is built using the popular GNU Automake, and thus provides the standard configure script. Before compiling, at least the following required dependencies must already be installed: 1) Cairo (http://cairographics.org/) 2) libjpeg-turbo (http://libjpeg-turbo.virtualgl.org/) OR libjpeg (http://www.ijg.org/) 3) libpng (http://www.libpng.org/pub/png/libpng.html) 4) OSSP UUID (http://www.ossp.org/pkg/lib/uuid/) ------------------------------------------------------------ Optional dependencies ------------------------------------------------------------ In addition, the following optional dependencies may be installed in order to enable optional features of Guacamole. Note that while the various supported protocols are technically optional, you will no doubt wish to install the dependencies of at least ONE supported protocol, as Guacamole would be useless otherwise. RDP: * FreeRDP (http://www.freerdp.com/) SSH: * libssh2 (http://www.libssh2.org/) * OpenSSL (https://www.openssl.org/) * Pango (http://www.pango.org/) Telnet: * libtelnet (https://github.com/seanmiddleditch/libtelnet) * Pango (http://www.pango.org/) VNC: * libVNCserver (http://libvnc.github.io/) Support for audio within VNC: * PulseAudio (http://www.freedesktop.org/wiki/Software/PulseAudio/) Support for SFTP file transfer for VNC or RDP: * libssh2 (http://www.libssh2.org/) * OpenSSL (https://www.openssl.org/) Support for WebP image compression: * libwebp (https://developers.google.com/speed/webp/) "guacenc" video encoding utility: * FFmpeg (https://ffmpeg.org/) ------------------------------------------------------------ Compiling and installing guacd, libguac, etc. ------------------------------------------------------------ All software within guacamole-server is built using the popular GNU Automake, and thus provides the standard configure script. 1) Run configure $ ./configure Assuming all dependencies have been installed, this should succeed without errors. If you wish to install the init script as well, you need to specify the location where your system init scripts are located (typically /etc/init.d): $ ./configure --with-init-dir=/etc/init.d Running configure in this manner will cause the "make install" step to install an init script to the specified directory, which you can then activate using the service management mechanism provided by your distribution). 2) Run make $ make guacd, libguac, and any available protocol support libraries will now compile. 3) Install (as root) # make install All software that was just built, including documentation, will be installed. guacd will install to your /usr/local/sbin directory by default. You can change the install location by using the --prefix option for configure. ------------------------------------------------------------ Running guacd ------------------------------------------------------------ If you installed the init script during compile and install, you should be able to start guacd through the service management utilities provided by your distribution (if any) or by running the init script directly (as root): # /etc/init.d/guacd start Root access is needed to write the pidfile /var/run/guacd.pid. You can also run guacd itself directly without the init script (as any user): $ guacd guacd currently takes several command-line options: -b HOST Changes the host or address that guacd listens on. -l PORT Changes the port that guacd listens on (the default is port 4822). -p PIDFILE Causes guacd to write the PID of the daemon process to the specified file. This is useful for init scripts and is used by the provided init script. -L LEVEL Sets the maximum level at which guacd will log messages to syslog and, if running in the foreground, the console. Legal values are debug, info, warning, and error. The default value is info. -f Causes guacd to run in the foreground, rather than automatically forking into the background. Additional information can be found in the guacd man page: $ man guacd ------------------------------------------------------------ Reporting problems ------------------------------------------------------------ Please report any bugs encountered by opening a new issue in the JIRA system hosted at: https://issues.apache.org/jira/browse/GUACAMOLE