Bits Are Bits! Right?

Apr 10, 2025 at 1:35 PM Post #46 of 48
Taking a binary fixed point A/D sample and turning it into a binary floating point representation is a simple format change that only involves bit shifting to form the mantissa, and an according adjustment of the exponent. That's a different ball-game from actually doing real-time filter calculations in 32bit float, but it could well be that for the latter the required float processors for use in consumer portable equipment are now available.
I’m no expert in the subject but I think you’re way, way out of date, at least as far as audio is concerned. What you’re stating was readily available 30 years ago. DSPs, were invented in the ‘70s and were pretty advanced by the 90’s. Motorola and others were making digital signal processing chips but I recall back in the mid 90’s when SHARC processors became the “flavour of the day”. Quite a few bits of digital studio gear around that time were advertising they used SHARC chips, which natively calculated filters (and other DSP tasks) in 40bit float and did it extremely quickly/efficiently because the actual chip instruction sets were built for real time signal processing applications, they could then internally convert their output to all the standard fixed point bit depths (up to 24bit) as well as 32bit float. The top of the range SHARC chip was like $8 or something but I haven’t heard of them for years, not sure they still make them.

As far as I’m aware, floating point calculations for filters, etc., in AD converters has been standard for at least 25 years, even in cheap converters.

G
 
Apr 10, 2025 at 1:57 PM Post #47 of 48
I’m no expert in the subject but I think you’re way, way out of date, at least as far as audio is concerned. What you’re stating was readily available 30 years ago. DSPs, were invented in the ‘70s and were pretty advanced by the 90’s. Motorola and others were making digital signal processing chips but I recall back in the mid 90’s when SHARC processors became the “flavour of the day”. Quite a few bits of digital studio gear around that time were advertising they used SHARC chips, which natively calculated filters (and other DSP tasks) in 40bit float and did it extremely quickly/efficiently because the actual chip instruction sets were built for real time signal processing applications, they could then internally convert their output to all the standard fixed point bit depths (up to 24bit) as well as 32bit float. The top of the range SHARC chip was like $8 or something but I haven’t heard of them for years, not sure they still make them.

As far as I’m aware, floating point calculations for filters, etc., in AD converters has been standard for at least 25 years, even in cheap converters.

G
If that is the case then indeed, I'm way out of date on that :xf_wink:; I had never heard of SHARC processors.

At least I'm getting back up to date with my choice of music. Now where's my walker...
 
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Apr 11, 2025 at 4:54 AM Post #48 of 48
If that is the case then indeed, I'm way out of date on that :xf_wink:; I had never heard of SHARC processors.
I just looked them up, they’re made by Analog Devices, were first released in 1994 and apparently are still available, now gen 6. There’s not much available from back then but here’s a couple of later examples I found:
EQ magazine - Jan 1998, page 87 - Lists Studer’s D950 digital mix system with SHARC chips.
2001 edition of Mix magazine, page 15 - This one is exactly what I mentioned previously, an advert for digital gear (a Fairlight Prodigy2) that states: “With a distributed processor architecture employing Analog Devices SHARC chips, Prodigy2 offers 40-bit floating point processing for effortless real-time DSP capability, no matter how complex”.

I find it interesting that there were many ads around the mid/late ‘90s for pro audio gear boasting of using these SHARC chips but the chips inside pro audio gear weren’t mentioned prior to this and I don’t remember them being mentioned after around the mid ‘00s. By then there were presumably various other chip manufacturers with more powerful and sophisticated DSP chips/solutions and SHARC chips no longer held the same cachet. Nevertheless, great marketing by Analog Devices for that decade or so, I assume there must have been some competitors but I don’t recall ever hearing of them.

G
 
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