Hi all, We're in the process of porting an open source Matlab toolbox to Linux called the Psychtoolbox. It's a piece of software that's widely used within neuroscience and psychophysics, to display graphics and play sounds in experiments. It uses OpenGl for its graphics backend, and right now the sound support is just matlab's, which is really poor. A lot of us researchers are interested in audiovisual experiments, where we study how the brain combines auditory and visual information (for example in speech perception). Concretely speaking, that means we need to get as precise a timing and synchrony as we can possibly get. A typical experiment will go something like this : - display a flash and, at the same time, play a beep - wait for response The tricky bit is of course getting a flash that's totally synchronous with the beep. Absolute synchrony is not achievable without dedicated hardware, but we need to get an approximation that's within the few ms range.

Hi all, We're in the process of porting an open source Matlab toolbox to Linux called the Psychtoolbox. It's a piece of software that's widely used within neuroscience and psychophysics, to display graphics and play sounds in experiments. It uses OpenGl for its graphics backend, and right now the sound support is just matlab's, which is really poor. A lot of us researchers are interested in audiovisual experiments, where we study how the brain combines auditory and visual information (for example in speech perception). Concretely speaking, that means we need to get as precise a timing and synchrony as we can possibly get. A typical experiment will go something like this : - display a flash and, at the same time, play a beep - wait for response The tricky bit is of course getting a flash that's totally synchronous with the beep. Absolute synchrony is not achievable without dedicated hardware, but we need to get an approximation that's within the few ms range. From what I've read it seems that Linux is a pretty good platform for that, since it has low latency/real time support. What I need to know is how I should go about implementing some kind of FlashAndBeep function, that guarantees that the sound starts playing as soon as the display buffer is flipped, with the shortest predictable delay possible. Is ALSA the way to go ? JACK maybe ? Anything else ? I'd love to read about any piece of advice you might have. Do ask me if you need more details. Thanks a lot, Simon Barthelmé PhD Student Laboratoire de Psychologie de la Perception CNRS/Université Paris V lpp.psycho.univ-paris5.fr