Jack audio server for multi-processor machines

International audienceJack is a low-latency audio server, written for POSIX conformant operating systems such as GNU/Linux. It can connect a number of different applications to an audio device, as well as allowing them to share audio between themselves. We present a new C++ version for multi-processor machines that aims at removing some limitations of the current design: the activation system has been changed for a data flow model and lock-free programming techniques for graph access have been used

jackdmp: Jack server for multi-processor machines

International audiencejackdmp is a C++ version of the Jack low-latency audio server for multi-processor machines. It is a new implementation of the jack server core features that aims in removing some limitations of the current design. The activation system has been changed for a data flow model and lock-free programming techniques for graph access have been used to have a more dynamic and robust system. We present the new design and the implementation for MacOSX

TIMING MEASUREMENTS IN JACK2

Timing measurements allow developers to help under- standing the behaviour of their JACK based applications. The server code base now allows to record various tim- ing while the server and clients are running and generate scripts to interpret them

Multicore technologies in Jack and Faust

International audienceTwo ongoing research projects at Grame aim at providing efficient solution for audio applications on many/multi core systems. The first one is Jack- dmp, a C++ version of the Jack low-latency audio server for multi-core machines. The second is Faust, a compiled DSP language with auto parallelization features. This paper will briefly describe these two projects focusing on multi-core related questions

What's new in JACK2?

International audienceJACK2 is the future JACK version based on the C++ multi-processors Jackdmp version. This paper presents recent developments: the D-Bus based server control system, NetJack2 the redesigned network components for JACK and profiling tools developed during port on Solaris

Container-Based Real-Time Scheduling in the Linux Kernel

In recent years, there has been a growing interest in supporting component-based software development of complex real-time embedded systems. Techniques such as machine virtualisation have emerged as interesting mechanisms to enhance the security of these platforms, while real-time scheduling techniques have been proposed to guarantee temporal isolation of different virtualised components sharing the same physical resources. This combination also highlighted criticalities due to overheads introduced by hypervisors, particularly for low-end embedded devices. This led to the need of investigating deeper into solutions based on lightweight virtualisation alternatives, such as containers. In this context, this paper proposes to use a real-time deadline-based scheduling policy built into the Linux kernel to provide temporal scheduling guarantees to different co-located containers. The proposed solution extends the SCHED_DEADLINE scheduling policy to schedule Linux control groups, allowing user threads to be scheduled with fixed priorities inside the control group scheduled by SCHED_DEADLINE. The proposed mechanism can be configured via control groups, and it is compatible with commonly used tools such as LXC, Docker and similar. This solution is compatible with existing hierarchical real-time scheduling analysis, and some experiments demonstrate consistency between theory and practice

Content rendering and interaction technologies for digital heritage systems

Existing digital heritage systems accommodate a huge amount of digital repository information; however their content rendering and interaction components generally lack the more interesting functionality that allows better interaction with heritage contents. Many digital heritage libraries are simply collections of 2D images with associated metadata and textual content, i.e. little more than museum catalogues presented online. However, over the last few years, largely as a result of EU framework projects, some 3D representation of digital heritage objects are beginning to appear in a digital library context. In the cultural heritage domain, where researchers and museum visitors like to observe cultural objects as closely as possible and to feel their existence and use in the past, giving the user only 2D images along with textual descriptions significantly limits interaction and hence understanding of their heritage. The availability of powerful content rendering technologies, such as 3D authoring tools to create 3D objects and heritage scenes, grid tools for rendering complex 3D scenes, gaming engines to display 3D interactively, and recent advances in motion capture technologies for embodied immersion, allow the development of unique solutions for enhancing user experience and interaction with digital heritage resources and objects giving a higher level of understanding and greater benefit to the community. This thesis describes DISPLAYS (Digital Library Services for Playing with Shared Heritage Resources), which is a novel conceptual framework where five unique services are proposed for digital content: creation, archival, exposition, presentation and interaction services. These services or tools are designed to allow the heritage community to create, interpret, use and explore digital heritage resources organised as an online exhibition (or virtual museum). This thesis presents innovative solutions for two of these services or tools: content creation where a cost effective render grid is proposed; and an interaction service, where a heritage scenario is presented online using a real-time motion capture and digital puppeteer solution for the user to explore through embodied immersive interaction their digital heritage

Development and Evaluation of a Real-Time Framework for a Portable Assistive Hearing Device

Testing and verification of digital hearing aid devices, and the embedded software and algorithms can prove to be a challenging task especially taking into account time-to-market considerations. This thesis describes a PC based, real-time, highly configurable framework for the evaluation of audio algorithms. Implementation of audio processing algorithms on such a platform can provide hearing aid designers and manufacturers the ability to test new and existing processing techniques and collect data about their performance in real-life situations, and without the need to develop a prototype device. The platform is based on the Eurotech Catalyst development kit and the Fedora Linux OS, and it utilizes the JACK audio engine to facilitate reliable real-time performance Additionally, we demonstrate the capabilities of this platform by implementing an audio processing chain targeted at improving speech intelligibility for people suffering from auditory neuropathy. Evaluation is performed for both noisy and noise-free environments. Subjective evaluation of the results, using normal hearing listeners and an auditory neuropathy simulator, demonstrates improvement in some conditions