Hi, I'm pretty new to Linux audio, but a project I'm working on is going to need me to generate musical notes on a remote Linux server, in (near-)realtime (i.e. changing the sound output based on realtime events). I have basically no familiarity with MIDI etc., but the easiest interface I've found for the starting and stopping of notes, so far, is the FluidSynth API. That's not the issue, however: the trick is getting the audio back to my Windows machine with low-ish latency, and in reasonable quality. To add a little interest to the scenario..., my Windows machine is also behind NAT and a firewall. The ping round-trip time is under 30 ms, though, so I'm hoping latencies of around 200 ms might be possible. Just to make life more interesting, I'd rather not have to use X Windows at all on the remote machine, as I'm blind, and haven't even begun to think about the ins and outs of accessibility of a remote X server (and, frankly, would rather just not go there for now). (The application I'm working on may interest you, BTW: I'm converting financial data, particularly currency price charts, into soundscapes, for "visualising" recent price movements. If it were just a one-off, I could convert it into an audio file and download it; but, instead, I want it to be interacctive, so I can rewind through the image, step backward or forward frame by frame, etc. I'm going to have fun with this!) I've been considering a few methods of getting the audio to my Windows machine, but none of the options I've come up with so far seem to quite work as I want. Here's what I've considered. 1. Send audio to JACK, then send it to the Asterisk PBX via the App_Jack application; listen to the audio via a softphone on the Windows machine, connecting to the Asterisk server via SIP. Sound quality wouldn't be ideal - 8KHz mono - but I could live with that. Unfortunately, it looks like App_Jack doesn't successfully connect to a JACK server: a bug report was lodged about it over 3 years ago, marked severe, but doesn't seem to have been fixed as yet. 2. Send audio via Jack and a streamer (probably DarkIce) to an Icecast2 server; then use a media player such as WinAmp or MPlayer. The problem here is buffering: 10-20 seconds of latency just isn't acceptable for the realtime aspects of the project, and I don't know if there's a way to get a media player to do unbuffered playback (a quick Google search seemed to indicate not). 3. Use netJACK1 to play audio direct from JACK (that's the only one of the 3 networked-JACK solutions mentioned on the JACK website that's recommended for use over a WAN). Unfortunately, once I dug into this, it looks like the assumption is that the audio will be played on a Linux box: there doesn't seem to be any provision for having the Windows machine as the one doing the audio playing. I did have a quick look at netJACK2, but that seems to assume the two machines are on the same LAN - you don't even specify the IP address to connect to! 4. I wondered about using PulseAudio. However, that seems quite tricky to set up without X on the remote machine, and I'm not at all clear about the NAT traversal issue. 5. I also wondered about NAS: I gather it's very outdated, but it sounds like about what I'm after. However, I couldn't find a Windows download; and FluidSynth doesn't have a NAS interface, as far as I understand it. TiMidity does, though, so I'd just need to work out how to send it MIDI events from software... Tunneling through a forwarded port (using ssh) may help in some aspects, but I'm not sure. AT least, it adds an extra set of possibilities, as do VPNs. As you can see, I've been wracking my brains over this for a couple of days, and while I've felt I'm really close on more than one occasion, I've not quite got there. Any input would be very much appreciated! Alternatively, if there's a better place for me to be asking this question, a pointer would be very helpful. Cheers, Nikhil. _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
