Re: [linux-audio-dev] Fwd: Opinions on running VST or DirectX plugins on Linux in real time

I contacted the author of the VQF plugin about opinions of running windows plugins under Linux. He is not subscribed to LAD so he told me to forward this mail to the list. cheers, Benno

On Tue, 22 Oct 2002, Benno Senoner wrote: DirectX audio VQF plugin I am afraid I will have to keep this short as I'm really busy at the moment. I also am a long way from being an audio expert or wine so I doubt my experiences will be of much use to you hence I didn't subscribe to the list . Feel free to forward this to the audio-dev list and cc me on it if you wish First, the solution I used for the VQF plugin was extremly clunky. There was no way of letting the plugin run inside XMMS without causing segfaults. They simply did not merge well no matter what I tried. I suspect but never proved that it was how WINE has to lay out it's memory to be able to mimic how Windows sees things like segments. The layout is drastically different to how a Linux app normally sees things. By the time a VQF plugin could be loaded, the two very differnet approaches to managing memory simply did not work well together In the end, the solution used was this; 1. At XMMS start, fork and exec an application that uses libwine to load the windows DLL. Communicate with the parent through pipes, sockets or shared memory 2. Start up XMMS as normal 3. The plugin just implements stub functions for every routine a plugin is meant to implement and communicates the information to the child This had a number of issues. First, it was difficult to get information from the plugin. It opened the sound device directly itself which meant that visualisation data was not available. At one point, this was resolved by hacking wine itself to write the PCM data to a named pipe rather than playing to a device but needless to say, it was too ugly to live and couldn't really be distributed easily. (I considered it unreasonable to get users to patch and compile WINE just to play a piece of music, visualisations weren't that important). If I had a nice plugin, what I would try to do is set up two unamed pipes at application start to a child application using libwine. One pipe for writing would send commands and one pipe for reading would take PCM data. I don't know how viable this is for you. small I would be inclined to go the other way. With the above solution, I would try and buffer as much data as humanly possible to try and avoid the overhead of calling wine constantly. For example, I would try and get 10 seconds worth of data from the windows plugin before starting to play anything. Once I had the PCM data, it would not matter if the plugin could not make real time contraints. excel It can, but remember that if you are trying to use this plugin with a normal application, you are likely to run into a lot of trouble. At least I did, but this was a few years back. Things might be different now I imagine you already have checked out how avifile loads it's plugins. When I last looked at it (a few years back), it was using a stripped down version of WINE to just load the plugins and get the function pointers. It might be worth checking into. -- Mel Gorman MSc Student, University of Limerick http://www.csn.ul.ie/~mel