Studer Infinity series white paper

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White Paper Infinity Processin P ng

Generallyy speaking ma ajor steps in audio design only happen everry decade orr so. The firsst realistic larrge scale digital mixer was de eveloped in the mid 80’s. This me 25,000 ICss, 80 units of rack space and a required som 6kW of powe er just to make e a 48 channe el mixer! In ord der to reduce this to a slightlyy more practiical size custo om silicon was designed d for th he next generration of mixe ers. This doubled d the channe el count in one o third of the t space and a quarter of o the powerr. This proce ess ut each develo opment was slo ow and costly. continued bu me of age wh hen the SHAR RC Digital mixers truly cam chip became e available aro ound 1994, th his offered mixxer designers off the shelf silicon which runs well in clusters, (aud dio processing g is a highly parallel p task; you y have to proccess many cha annels at the same time) has h long word le engths and su uitable softwa are developme ent tools are ava ailable to creatte audio proce essing function ns. In the mid ‘90 0s up to 100 or o more of the e first generatiion SHARC chips were used to t create a larrge scale mixiing desk, the DSP D took nin ne units of rack space and a consumed some 500 wattts. Over the next 15 yea ars, successive versions of these chips became mo ore powerful, goiing from some e 120 Mflops to 2700 Mflop ps. (Mflops = Million Floating Point operations per Seco ond ommon way of o defining pro ocessing powe er). which is a co The latest Studer use of SHARC chipss in the Vista a 1 o SHARC chips uses only 8 of the currentt generation of to mix nearrly the same e number off channels and a consume only 25 watts. Th here has been n about a 22 fo old increase in the processing power off these SHAR RC chips over the last 15 yearrs or so. Field Pro ogrammable Gate Arrays (FPGAs) ha ave become quitte widely use ed in the pro ofessional aud dio industry and they have also a become larger over the t ommitted “sea of years. They are basically a huge unco gates” that may m be linked d together to form multiplie ers, registers, adders and so forth. f Howeve er, programmiing them to proccess audio is more comple ex. For examp ple, changing a multiplier m used d to calculate e an FIR filter (a common tassk in audio processing) p in nto a routine to calculate FFT Ts (such as metering m displa ay) is hard to do and prone to o errors. The lack of suitab ble developme ent tools to build d the FPGA co ode in the field also makess it impossible fo or customers to construct their own DS SP configuration ns. Flexibility of configuration is a hu uge benefit to cusstomers as it allows them not n only to ada apt their mixer DSP D to meet th heir needs when they install it. It also allows changes to the con nfiguration affter

STUDER - Infinity Core C - White Paper

pu urchase, for example th he provision of surround d ch hannels with the advent of high definition n TV and new w prrocessing algo orithms such as automatic c mixing. Forr this reason FPG GAs are not sseen by Stude er as suitable e for large scale audio a signal processing for the future. The use off both SHAR RC and FPGA A devices forr au udio processin ng always requires significa ant R&D; each h tim me a new gen neration of chips become av vailable much h R& &D effort musst be invested into new board design and d maybe new pro ogramming. F For this reason n, most audio o SP engines are replaced only every 5-7 years, in n DS orrder to maximiise the return on R&D inves stment. Standard CP PU chips, the x86 types as used in huge e nu umbers for ge eneral compu uting, are very y suitable forr no on-real time signal processing. They are easy to o prrogramme, ma any developm ment tools are available, the e sh hipping volum mes are huge,, so much efffort goes into o de esigning the chips and th he PCBs use ed to supportt them. Of vital sign nificance is the processing power of x86 6 ch hips has incre eased some 5 5,000 fold in the same 15 5 ye ears that SHARC chips havve increased in n power some e 16 6 fold. This doubling d of p power every 24 2 months iss kn nown as “Mo oore’s Law”. The dream m is to take e ad dvantage of th his effect in Stu uder’s new ge eneration DSP P en ngine. Modern n CPUs use m multiple hardw ware “cores” to o ob btain the huge e processing power offered d today (clockk sp peeds have reached a plateau due to physicall co onstraints). Currently high--end CPUs have h 8 to 10 0 co ores, each of which may be e set to run 2 threads thuss do oubling the processing power. This s “multi-core”” technology is very suitable for large scale audio o prrocessing due e to the para allel requireme ents of audio o mixing engines.. However, th here is a kille er problem; x86 CPUs are e esigned as general g purpo ose processorrs and everyy de no ow and then, they t stop to do o some house ekeeping such h as s RAM refresh hing or temperrature sensing g. This is not a prroblem for most m computin ng, a momen ntary “pause”” wh hilst saving a file is of no consequence e but a single e missed audio sa ample results in an unaccep ptable click. In order to avoid this prroblem, normal x86 based d au udio signal prrocessing add ds audio buffe ering or delayy so o that CPU in nterrupts do not affect the flow f of audio.. Fo or real time “live” audio, th his delay or latency l is nott ac cceptable. The buffering a also reduces the efficiencyy an nd thus reducces the channel count. Stud der has found d

HIA/20.1.2014

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