Sulpha, so good

Sulpha, so good

By Develop

September 19th 2008 at 10:00AM

Itâ??s now three years since the coding team behind PS3 audio graced the first Develop conference en masse for an exciting audio track session which saw them emerge from behind closed doors to talk publically about their pioneering work.

As senior member of audio manager Jason Page’s crack team, Oliver Hume has played a key part in that story, developing the train tracks on which our audio work for PlayStation runs. He has a continuing role of developer support and the provision of vital tools to harness that now ‘current-gen’ raw power for the delivery of ever more sophisicated music, sound and dialogue. So how does he feel the PS3 audio tech has bedded down – and are developers fully realising the power of PS3 for sound?

“It’s bedded down well,” he says. “Audio developers have got the hang of the SPUs and we’re increasingly seeing more advanced applications – for instance, Codemasters have started using Ambisonics. This kind of CPU-hungry processing is now possible!

“We’ve been impressed with DSP usage. Originally, we saw ‘vanilla’ DSPs – one reverb per area, compressor at the end etc. Now we’re seeing multiple reverbs to simulate reflections from all directions giving a much richer experience with people routing sounds through multiple reverb rooms correctly, so the effect of each reverb as raytraced to the player is accumulated properly. Then there’s the use of DSPs at stream level – filters on every single sound playing, giving the audio a much more natural feeling, for example. We aim to continue enabling audio designers, giving them the technical freedom for their creative needs with virtually ‘limitless’ channels and DSPs.”

All well and good, but clearly many developers still opt for a common cross-platform solution with an inevitable ‘lowest common denominator’ factor. Hence the importance of tools which provide greater hardware access making it quicker and easier to push the envelope. Add to that an open-source, open-format philosophy allowing porting to other platforms, and one can see the possibilities that these tools can help raise the overall quality bar.

Enter Sulpha – a high level MultiStream PC based debugging audio tool. Hume explains that Sulpha is designed to let users debug every part of MultiStream with ease: “Developers often have problems balancing their in-game levels – monitoring dozens of individual bus routes, the master balance and their mix down balance. Only one route needs to run hot for the whole game to sound clipped and distorted. Then there’s balancing the SPU load of MultiStream, especially when using a lot of heavy-duty DSPs. Sulpha lets you see the exact SPU processing cost of each stream and bus in real-time.”

All of which should speed up development. Previously when a developer reported a problem, there would be a period of enquiry about their setup, and usage of MultiStream. Now they can attach a Sulpha capture with their initial bug report and the Sony team have all the information they need for diagnosis and resolution.

“Sulpha exposes all the workings of MultiStream,” adds Hume.
“With minimum changes the developer can connect the PC tool to their running instance of MultiStream and capture every single piece of data used,” he continues. “They can then step through and watch the effects of each instruction called on the various parts of MultiStream - in the same way as a code debugger.

“The audio data of every stream playing is captured together with all mixing buses in real-time allowing a developer to listen to each of their assets as played through MultiStream. They can hear the before/after effect of their DSP chains and monitor the levels of every one of their buses and the final down-mix. API usage can be viewed, as can the order of calls – and you can see any functions that returned an error code. You’d be surprised at the number of bug reports where the developer isn’t checking error returns! Finally, you can view a 3D spatialization of your surround to quickly see if sounds are grouped correctly.”

Hume believes the new tool will have a tangible effect on quality by reducing the time required to debug audio, thereby freeing up development time for polishing and implementing features.

Meanwhile, being able to get at the sub-bus feeds means non-programming audio guys can check various audio portions easily, and seeing accurate resource-usage reports may uncover spare capacity for extra trickery such as mastering EQs, compressors, soft limiters and so on.
Hume is keen that the tool gets the most use possible, even on non-Sony systems: “As far as the cross-platform angle goes, we're acutely aware that people aren't using MultiStream to its full potential, due to that old 'lowest common denominator' phenomenon. With our future engines we're going to release the PC based source code as well, which developers can port to other platforms.”

Sulpha will be available for PlayStation 3 registered developers within the year. Also, look out for other future tool releases including Awesome – Sony’s next audio scripting solution – and modular based synth engine, Fusion.