There is no way of doing real-time processing over a network reliably. Dropouts and timeouts, packet retries are in the nature of computer networks. UDP is a very smart way to (try to) send realtime data through a network. If the implementation is at least average, that is the best performance you can get. You can't have realtime low-latency audio operation through a non-controlled network environment (like the internet). .. But the bright side is, as Rohan Drape (the author of jack.udp) says: "In practice this mechanism can be made highly reliable over local networks." jack.udp is probably as good as it gets. If you have problems, use a larger ring buffer size, place the computers more close to each other on the network, reduce other load on the router(s) between the computers. Sampo On Wed, 2004-08-18 at 15:06, Luke Yelavich wrote:

On Wed, 18 Aug 2004 16:13:21 +0300 Sampo Savolainen <v2(a)iki.fi> wrote: Along similar lines, a friend of mine had been working on some code (unfortunately in a Windows environment, and in a programming language that he developed himself(!) so the work's not available to me) to do something I'd love to implement: synchronized streaming. I live in a house with 4 distinct areas, with network connected music systems in each area. When I have a party, I'd love to have each of these machines tie into a stream from my audio server so that they're in sync - that is, if I can hear 2 different systems at the same time, I want them to be at the same place in the stream, not a second or two off from each other. Has anyone heard of anything under Linux that would do such a thing? (It just occured to me that tapping into such a stream with a buffer of size 0 may do it, though that could open me up to hearing every little network burp encountered. I'll have to try that tonight!) -- ====================================================================== Joe Hartley - UNIX/network Consultant - jh(a)brainiac.com Without deviation from the norm, "progress" is not possible. - FZappa

On Wednesday 18 August 2004 15:20, Joe Hartley wrote: I don't think the problem you describe is anywhere near as simple as just getting the streams into sync - although it depends on the size, and to some extent the shape and construction of the house. You have to consider how the sound reaches your ears from each set of speakers, and this is far from straightforward since sound waves of different frequencies are likely to travel by different routes. Sound reflection, diffraction, absorbtion and interference all affect different wavelengths differently. The simplest way to get the sound in 2 zones in sync is to transmit the analogue audio between the two; if you do that, and stand in the middle, you'll get far from perfect sound in the middle spot, because of these effects which tend to outweigh the loss of quality through attenuation and interference in the analogue electrical stage in the wires. Your proposal (synchronised streaming) effectively resolves the analogue attenuation/interference issues by using digital transmission in the wires, but ignores all the acoustic effects. However, there may be another application.... In bars and other public places, the current fashionable trend for hard [white] walls and ceilings which reflect shorter-wavelength sounds well exacerbates the conflict between music and conversation, so that it becomes impossible to hear either above the din of both. Bass notes are much less affected and travel well at ground level through a mass of people. I think it should be possible, with a combination of softer sound-absorbing surfaces and smaller, localised mid-range and treble speakers, to create in a busy place like a bar an acoustic environment where the volume of conversation and music is as balanced as it is in your living-room with say half-a-dozen guests. This might require some variable multiple millisecond delays to be introduced to the signal to the localised speakers so that the treble is in sync with the bass... This is however, nothing more than a thought experiment brought on by the frustration of spending too much time in such noisy environments, so I'd be glad of comments! Edward Barrow

Joe Hartley wrote: No, and I'd echo the caveats that Edward Barrow mentioned (if I had to do it, I'd run speaker wires to speakers distributed throughout the house (or preamplified audio signals to amplifier/speakers throughout the house) rather than lan cable to computer/amplifier/speakers throughout the house. However, I just thought I'd mention, in case someone seriously wants to attempt something over a lan, there is a way to do multicasting with TCP/IP, and that may be needed to get as close as you can get to synchronization. (But, with varying processing latency in each computer, I'm not sure that would be anywhere close to satisfactory.) Randy Kramer