Remind me - Soundflower/Mac

[Dave2002]

I reconnected up a "hi-fi" system today, and put together speakers, DAC, CD and amplifier. Results very pleasing, compared with what I've been listening to recently, though probably not the best system I could configure. I'll experiment during the coming week.

For my final trick before turning in for the night I connected my MBP with a USB cable to the DAC and switched to the Soundflower output to drive the DAC. On disconnecting it, I noticed that there are two Soundflower options. One is 2 channel - obvious - stereo, the other is 64 channels. How does one sensibly use a 64 channel output? If I had suitable kit, I might be able to drive 5, 6 or 7 output channels - and I might just manage that with the equipment I've got.

So there are really two questions here -

1. How do I get multi-channel output with n channels for n>2 and n<=64? In particular, what about n=4,5,6 or 7?

and

2. even if I can output a lot of channels, where do I get multi-channel sources with (say) 24 channels?

Why was Soundflower developed with this possiblity? Future expansion?

[Bryn]

https://github.com/RogueAmoeba/Soundflower-Original/issues/53

[Dave2002]

Mmmm.

Doesn't quite do it for me, but ....

i suppose my major concern is the number of physical outputs. Perhaps some commercial enterprises (e.g. theatre or cinema sound systems) could really use 64 channels (even more ....), but most of us mere consumers are likely to struggle with more than 10.

In the linked page esaruoho mentions linking together different packages, but I'd have thought that for many purposes some form of "virtual" connection would do to link software packages together - though maybe Soundflower can do that. With audio at (say) 48 kbps sampling, getting 64 channels a data interface would have to run at 3*2^12 kbps (or more) - approx 12 Mbps to service all the channels in real time, though the data rate could be lower if only a few of the 64 channels are active at any one time. Active channels could be determined by flags in the data stream. I think modern computers can do this sort of thing easily, though getting the timing between channels accurate might take a bit more work.

Output to physical soundcards could introduce delays between channels of the order of a microsecond, which for stereo would be all but inaudible, and even for 64 channels the delay between channel 1 and channel 64 would be of the order or less than a tenth of a millisecond, so again in practical terms probably possible to ignore that. Delays between channels could be larger if each channel used packets of data, and then some form of delay offsets might be required to avoid audible problems between each audio channel in the listening room.

Multi channel streamng with a large number of channels could be more complex.

Mere consumers might now wish to have computers with (say) 10 physical outputs (extendable to more) driven by a suitable compound data stream. That way they could drive a typical surround sound AV system quite easily. I don't see such a product available right now, though more specialist sound engineers probably make and use such kit.

I don't think many of us here have experience of using either software (virtual) or physical interfaces for multi-channel systems with more than 2 channels (stereo).

[MrGongGong]

I often use 8 or more channels when making things.
I've used 64 channels when working with orchestral recordings and even done things with more for installations etc
There are several playback and performance systems in the UK (and many elsewhere) that use this number (and sometimes more) channels

BEAST in Birmingham being probably the best known but lots of others in Sheffield, York, Manchester, London etc etc

[Dave2002]

mrgg

I suspected as much, but presumably the places you mention use specialist kit and sound engineers. Possibly all bespoke kit.

Few consumers use more than 2 channels I think, though now that multi-room systems are becoming slightly more common, then there may emerge some new types of equipment for domestic use. Also, systems with a large number of channels may not always need strong coherence between channels, so some of the issues I hinted at in msg 3 might not be relevant. Examples would be an intercom system within a building. For sound installations such as the ones I think you work with, getting (fairly) coherent sound channels could be important.

I can't see any easy to use multi-channel systems coming on the horizon in the near future - though I suppose systems based on wireless technology may do that. Adding in yet another channel is relatively easy with wireless technology, though then the problems are different, as wireless communications don't always work very well, so going for ease of installation may counter good/satisfactory operation.

[MrGongGong]

I think lots of folks have 5:1 and 7:1 systems in their houses?

There are heaps of things about multi-speaker systems including the whole issue (or non-issue depending on what you are doing) of phase etc
Wireless multi-channel is tricky and very expensive and impossible with Bluetooth (sadly) at the moment
but there could be a "domestic" version of this kind of kit which would "stream" via CAT5 cabling

https://www.audinate.com/solutions/dante-overview

[Dave2002]

I think lots of folks have 5:1 and 7:1 systems in their houses?

There are heaps of things about multi-speaker systems including the whole issue (or non-issue depending on what you are doing) of phase etc
Wireless multi-channel is tricky and very expensive and impossible with Bluetooth (sadly) at the moment
but there could be a "domestic" version of this kind of kit which would "stream" via CAT5 cabling

https://www.audinate.com/solutions/dante-overview

Thanks.

Not quite sure why you are sad that Bluetooth doesn't work at the moment. I'm not certain of the latest Bluetooth standards, but doesn't the highest/latest standard rely on an infrastructure network - so it's not a straightforward peer to peer networking system? The bandwidth available over a Bluetooth link is insufficient to cope with anything really complex or high quality AFAIK. However there are also problems with infrstructure systems as they may not be able to guaranteed latency times for multiple devices. The same might also be true of ad-hoc networks, except that the latency might be a lot lower because of the protocols used.

I'll need to read this and other articles to catch up - https://en.wikipedia.org/wiki/Bluetooth

[MrGongGong]

AFAIK Bluetooth audio doesn't work for more than 2 channels is what I meant
I spent some time a couple of years ago trying to see if it was possible for a piece I was installing in a large building with 8 speakers but in the end the choices were either very expensive (out of budget but very cool) wireless systems or "miles" of singnal cables.... I went for the latter though it would be good to be able to have multichannel transmission some time in the future.

[Dave2002]

Agreed that it doesn't seem feasible for Bluetooth to work for more than 2 channels at present. I suspect that if you need wireless in a large environment you need to use at least one wired LAN within the environment, with several wireless access points to create links to mobile units (speakers). Possibly some large environments might actually be able to provide that, but this is not the sort of configuration that most domestic users will try for.