This is the fourth AoIP spotlight article looking in a little more detail at how particular technologies work and how they differ from each other. So far I have looked at AVB, Dante and RAVENNA and by categorising these in terms of whether they are open or proprietary technologies and looking at on which layer of the ISO 7 layer model they reside we can see that we have Dante (Layer 3, proprietary), RAVENNA (Layer 3, open) and AVB (Layer 2, open). We have three corners of a square (see below), but is there a layer 2 proprietary technology out there to fill that bottom left corner? There is, its SoundGrid/DigiGrid....
When a system is set up and working it makes little difference on which layer it operates but in terms of orientation I think it's helpful to lay out the landscape in this way and while all of these technologies do the same thing, they all do it slightly differently and in the case of SoundGrid is it more than just an audio network, it is a processing environment too.
What Is SoundGrid?
SoundGrid is an AoIP technology which offers audio transport over standard gigabit networks and real-time audio processing on Intel CPUs, all with deterministic latency. This audio processing capability is a key difference between SoundGrid and the other AoIP technologies discussed in these spotlight articles and is possibly a reason why it is perhaps less well understood than some of the other contenders.
What Is The Difference Between DiGiGrid And SoundGrid?
One of the potential areas for confusion is the use of two similar names in connection with this technology - SoundGrid and DiGiGrid. SoundGrid Is the name of the technology itself - the network glue which underlies the system. DiGiGrid is the name of the brand whose devices use this technology. So, for example, you could have a SoundGrid network using non DiGiGrid devices (for example Waves Also make SoundGrid hardware) but you couldn’t have a network of DiGiGrid devices which didn’t run using SoundGrid.
Is SoundGrid A Network Or A DSP?
To many it is known as a way to connect a SoundGrid Server like a DiGiGrid DLS to a workstation or digital mixer to host Waves plugins in a DSP like manner - remember SoundGrid servers use Intel CPUs (i.e. standard computer hardware) rather than DSPs but using dedicated hardware for audio processing is “DSP like” but doesn’t involve any DSP chips. Users of the Pro Tools Native hardware might only use their DiGiGrid hardware across a single connection from the server to the computer to access plug-ins.
To others, particularly users of the desktop range of interfaces it is seen as an AoIP network - A method to transport and distribute audio using network cables. I was full of praise for this approach in my Audio over IP - Is Smaller Better? article but this range could be seen as separate or different in some way from the bigger Pro Tools and Native hardware ranges. However, it is all DiGiGrid hardware and can coexist on the same network.
Components Of A SoundGrid Network
SoundGrid uses standard gigabit network hardware - CAT5e cabling and switches which support jumbo frames (i.e. most modern switches). Over this hardware, it can pass uncompressed audio at up to 32 bits and 96kHz. Maximum channel count is 512 channels at 48kHz, lower maximum channel counts come into effect in certain applications, for example, 128 channels over the Core Audio and ASIO drivers.
It used to be the case that the only non-standard part of a SoundGrid network was the audio interface. The work of converting a digital audio stream into network packets at low enough latencies for professional use is best done using dedicated hardware but the recent introduction of SoundGrid Connect introduces the possibility of using any Core Audio or ASIO interface as a SoundGrid IO.
Perhaps the most familiar incarnation of the SoundGrid system is running a server with a live console or DAW to offload processing overhead to a server. Indeed DiGiGrid hardware first came to my attention as the preferred alternative host for Waves’ plug-ins when they announced they wouldn’t be supporting AAX DSP. In this configuration with a SoundGrid server for audio processing end-to-end latency is less than 1ms.
SoundGrid Connect is a recently introduced software product which exposes any Core Audio or ASIO interface to the SoundGrid network allowing it to be used as an IO on a SoundGrid network, with or without additional DiGiGrid servers or IO.
DiGiGrid forms the basis of a robust, high-performance AoIP network which, because it is proprietary offers excellent compatibility within its own ecosystem. Uniquely among the AoIP solutions I have featured in these spotlight articles it supports both audio transport and processing and while it offers limited interoperability, as it doesn’t support AES67, for users who want the advantages of networked audio and the possibility of offloading the plug-in processing overhead of Waves and third parties such as Plugin Alliance to DSP it offers a unique solution.