BestTechVideos: Tag linuxconf-au Videos

LinuxConf.Au: The PulseAudio Sound Server

scoundrel — Thu, 17 May 2007 22:39:17 GMT

PulseAudio is a sound server for Unix/Linux and Windows systems. As such it is a proxy for audio applications, handling mixing of multiple audio streams and network transparency of audio output and input.

PulseAudio is intended to be a compatible drop-in replacement for the GNOME sound server EsounD. To the functionality of Esound it adds some new features, such as an extensible plug-in architecture, a better low latency behaviour, a greater variety of supported sampling formats and more accurate timing. It features a modern zero-copy memory manager which reduces CPU and memory load. An extensive set of GUI tools for configuration and management are available. In addition to the almost complete compatibility with the EsounD protocol the sound server can be accessed through the ALSA and the traditional OSS APIs, thus reaching compatibility with 90% of the Linux audio applications.

The scope of application for the PulseAudio sound server is large and diverse, ranging from embedded devices for networked audio, to thin client audio, to normal user desktop audio.

PulseAudio is part of a few commercial products. It is our intention to replace Esound as default GNOME sound server in the near future.

The sound server is available as part of a range of major distributions, such as Fedora, Gentoo, Mandriva, OpenSUSE. By the time of linux.conf.au it is very likely that it will be available in Debian GNU/Linux and Ubuntu, too.

The presentation that I am proposing will be an introduction into this sound server and its possibilities. It will include a more extensive overview of the feature set mentioned above, a quick presentation of the currently available plug-in modules and a list of third-party applications which currently support PulseAudio natively.

I will demonstrate a few tricks which the sound server can do for the user. In particular I plan to show hot-plugging of sound devices, gap-free switching of active audio streams between multiple audio devices, synchronous playback of a single stream on multiple devices with differing crystals, Avahi/Zeroconf functionality, RTP multicast streaming, X11 and GNOME integration, the GUI tools, the "Window Manager for Sound".

I plan to compare PulseAudio's possibilities with the upcoming Microsoft Vista sound architecture and PulseAudio's relation to the GStreamer GSmartMix project. Subsequently I will talk about comparing PulseAudio do other Free sound servers, which are arRts, JACK, and of course Esound.

Then I would like to give an outlook on the near-time future of PulseAudio, including upcoming new features and adoption by third-party applications, distributions and other projects.

Finally - and only if time permits - I plan to give a quick introduction on the PulseAudio configuration language which can be used to adapt the sound server to the personal needs.

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LinuxConf.Au: Fixing suspend for fun and profit

scoundrel — Mon, 14 May 2007 10:54:37 GMT

Suspend to RAM is now a mostly solved problem under Linux. Resuming, however, is less so. Many drivers fail to support suspend and resume correctly, resulting in a range of failures from the individual device not working to the entire machine crashing. The most common workaround is to unload drivers on suspend and reload them on resume, but this reduces the incentive to fix the bugs while increasing the time taken to complete the suspend/resume process. This presentation will cover what a driver needs to do in order to work over a suspend/resume cycle, discussing the most common failures in drivers. A basic working knowledge of C is assumed, as is the ability to compile a kernel, but no deep understanding of the kernel source tree is required.

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Browse the archive of posts filed under OS, Conferences, Development, Broadcasting, Linux, LinuxConf.AU, Debugging, C and C++, Lectures

LinuxConf.Au: Practical Application of Software Defined Radio

scoundrel — Sun, 13 May 2007 16:14:38 GMT

The fundamental idea behind Software Defined Radio (SDR) is to replace as much of the dedicated analog electronics in radios and related communications systems with computer software as possible. This can both make existing communications systems more flexible, and enable entirely new applications.

This tutorial will reprise the technical and political background material on Software Defined Radio and the GNU Radio project presented by the speaker at the last two LCAs. Then, a mixture of demonstrations and hands-on activities will show participants how to get started using GNU Radio to participate in this fascinating area of Open Source development.

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LinuxConf.Au: The Kernel Report

scoundrel — Fri, 11 May 2007 08:44:00 GMT

The Linux kernel is one of the largest and fastest-moving free software projects in existence. This talk will bring attendees up to date with a comprehensive summary of what has been happening with the kernel and where it can be expected to go from here. We'll talk about the process by which the kernel is developed, issues which are currently driving development, and the changes we can expect to see from future kernels.

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LinuxConf.Au: Docks, Bays, and Ports: Not just for oceans any more

scoundrel — Thu, 10 May 2007 09:17:54 GMT

For many years, the only devices the Linux user could reliably hot plug were USB and PCI. 2006 was the year that users of Linux on a laptop finally realized the dream of being able to hit the eject button on their dock station and have it actually do something other than crash or hang. As if that wasn't exciting enough, later in 2006, thanks to the addition of hot plug support to the SATA layer, removable drive bay support became a reality as well.

This presentation will discuss in a generic way how we insert and remove devices into a system, the subsystem interactions required, and the user space notification process. We will discuss the new dock station driver as a specific example of a set of removable devices, and also show how the bay driver was ported from the dock driver to at last allow users to dynamically swap out the drive bay on their laptop.

All removable devices have generically the same behavior - detect that the device state has changed, and then create or destroy the device structures that represent the device to the OS. They all must alert their respective subsystems that a new device exists, and handle user notification as applicable. Some subsystems easily accommodate hot plug (such as PCI), while others are not quite ready for removable devices (such as PATA). Some removable devices are required to work with multiple subsystems (such as the dock station driver). For the devices that we will cover, we will show how the drivers interact with the different subsystems. In some cases we will show specific workarounds that we have had to do in the driver to accommodate lack of hot plug support in the subsystem. We will also delve into some of the lower level system support that is required in order to physically remove a device without damaging the system. We will discuss how ACPI is used to assist this process, and show how different system manufactures can implement the same feature in many different ways. Finally, we will describe the common software tasks that are required to insert and remove these devices at the kernel level as well as give an overview of each device driver's unique implementation details.

Not only is kernel support required for removable devices to be inserted or removed from a running system without catastrophic results, but support in user space is also essential. User space notification of removable devices isn't standardized, and there are a variety of strategies that are employed by kernel drivers to communicate to user space. We will discuss how each separate device communicates events to user space and demonstrate how user space applications can obtain knowledge of the insertion and removal, and how they might take advantage of this knowledge.

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LinuxConf.Au: Computers, Programs and Logic: What Does Linux Prove?

scoundrel — Wed, 09 May 2007 11:34:36 GMT

A Complete Beginner's Introduction to the Mathematics of Computing

Most hackers have heard of Turing Machine, the Halting Problem and the Godel's Incompleteness Theorem. Most hackers firmly believe the the following facts:

Turing was cool.
Godel was even cooler.
Neither Turing nor Godel are relevant to the Linux Kernel.

In the space of 45 minutes, I will endevour to confirm the first two beliefs and refute the third. I will give a complete crash course in the mathematics behind Turing's results and how it applies to the very practical problem of programming in C, without assuming any prior knowledge of formal logic beyond boolean arithmetic.

I will explain the connection between Turing Machines, Lambda Calculus, types, Classical Logic and proofs, and further discuss the place of Godel's Second Incompleteness Theorem in the whole maze.

Without assuming any familiarity with formal reasoning or theorem provers, after the presentation, the audience will have a fundamental understanding of the Curry-Howard Isomorphism that gives the connection between programs, their types, theorems and proofs. They will leave the talk with an understanding of what can and connot be done with C to ensure that their programs are always correct, from the first time they type "make" on the command-line.

At the end of the presentation, the audience will be pointed to open-source tool Twelf that allows practical exploration of the ideas presented in the talk.

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LinuxConf.Au: Desktops on a diet - old pants back on!

scoundrel — Wed, 09 May 2007 00:20:37 GMT

In the race to gain desktop acceptance (and mimick as much as possible from the "big" desktops out there - Windows, MacOS-X, etc.), The main desktop players (GNOME and KDE) have also gained weight. A lot of it. Speed of the software has slowed down at the rate hardware has sped up, or even faster.

In many cases they no longer fit in the pants people used to wear, and the pants people in developing nations can afford. In that rush and enthusiasm a lot of people have overlooked the alternatives - Desktop environments, shells and window managers that consume significantly less resoruces, and may give sufficient functionality, such as Xfce and Enlightenment.

This will focus on the upcoming release of Enlightenment 0.17 and its feature-set, efficiencies, subsystems, and related projects. What it can do and scale down to, as well as scale up to, what kind of people might have an interest in using it (those without the latest top-of-the-line systems with modern closed graphics drivers, those in developing nations or those simply with better things to do with their hardware resources). To get more efficient use of your system does not require the environment to be minimal and austere - it just requires making the right choices in design and implementation.

This will cover:

Eye candy - without closed drivers and mega-fast systems
State engines & X latencies & design
Fast rendering engines & canvases in X and other display targets
XRender, XComposite etc. extensions
Why open X drivers are better
File manager and application management basics
What libraries are behind Enlightenment that can help create efficient custom UI's
Pants

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Ensuring your device is not supported under Linux: Lessons for hardware vendors

scoundrel — Mon, 07 May 2007 09:17:46 GMT

With the increasing popularity of Linux in the embedded, desktop, and server world, HW vendors are jumping on the bandwagon to add support for their devices/chipsets/SOCs to the kernel; however, we in the community keep seeing the same mistakes (both technical and social) being made over and over again. In this talk I will give some examples of what to do if you want your HW to never be supported by the mainline kernel along with how to build a strong internal Linux team composed of very experienced developers that uses large amounts of resources to write code that is immediately rewritten by a college-aged kernel hacker upon being released to the community. Audience participation and sharing of stories is highly encouraged!

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LinuxConf.Au: How to Build an Open-Source Segway

scoundrel — Sun, 06 May 2007 09:58:21 GMT

Building a self-balancing scooter like the Segway(R) has previously been shown to be "not actually very hard" by Trevor Blackwell. I have replicated his experience by building my own two-wheeled self-balancing ride-on robot using only off-the-shelf parts, and open-source hardware and software.

The presentation will go through how my scooter was built and the theory and practicalities of keeping it upright, along with a demonstration.

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LinuxConf.Au: “How to” Build Custom Microcontroller Projects for Fun and Profit

scoundrel — Sun, 06 May 2007 09:49:46 GMT

This presentation looks at how to develop your own custom microcontroller hardware from scratch. Often laptops and general purpose computers are too powerful and too large to use for simple hardware projects. Often you can perform tasks like controlling DC motors, stepper motors, switches, LCDs, LEDs, buzzers/speakers etc. efficiently and effectively using inexpensive/free microcontrollers. Other benefits such as extremely small size and ultra low power consumption are also inherent benefits of most popular microcontrollers.

I will describe the Texas Instruments MSP430 family of microcontrollers, a powerful low voltage microcontroller that can be obtained at no cost using techniques I will show you. I will describe the entire process needed to develop your own projects starting with where to obtain free microcontrollers, the process needed to design and etch your own Printed Circuit Boards. Followed by a “how to” explaining the process needed to set up GCC and associated tool chain so you can develop software four your newly developed project hardware.

I also have a number of interesting previous projects that demonstrate how I have used the controllers in the past. This demonstrates how to implement RS232 serial ports, Bluetooth, simple bus design, Buttons (I/O), LED indicators, LCD, Analogue to Digital Converters, motor controlling (PWM), stepper motors and more. Over time while working on these projects I have compiled many of the different design features into a generic board. Both schematic design and code examples will be available for interested parties.

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