3 ms·

I'm kind of interested to see what bfloat16 sounds like (for audio DSP). I'd expect it to be good enough for a large number of algorithms so long as they are pr

I'm kind of interested to see what bfloat16 sounds like (for audio DSP). I'd expect it to be good enough for a large number of algorithms so long as they are properly stable, and if we have decent performance and reduced power use, i'm all for that!

rbanffy 6y ago
Probably not as crisp as 16-bit integers - mantissa is 7 bits, so 8-bits with sign. Clever use of exponents may give some additional range, but I wouldn't be too optimistic. The good thing is that, as any FP number, can represent a very large range of values, so I'd expect percussion and other things with very high-frequency transients to sound nice. My bet is it'll sound "colorful". IEEE float16 should sound better. But I'm no expert and I don't have the time to write something that force a good high dynamic range track to be rounded to the nearest bfloat16 and then expanded back. Also, I don't have gear good enough to hear anything better than CD-grade audio.
klodolph 6y ago
I’m sure you could come up with an application for it, but if you want audio output at some point, half-float sounds like quite a challenge. - The -66dB noise floor is pretty bad, and it accumulates at every step. - 11 bits is probably not enough for filter coefficients. So your filters would likely be running with single precision floats, at least. Even low-cost DSP chips tend to give you a big chunk of bits for your filters. - Naïve oscillator designs would accumulate a lot of error. Back of the envelope calculation, if you wanted an oscillator at C4, you’d likely be around 1/4 tone sharp or flat unless you ran the oscillator at higher precision. I’m definitely of the mind that bit depth is overrated in music. 16 bits is great-for mastered music and simple tweaks. By contrast, from my experiences writing DSP code, it often makes your code simpler and faster to run at higher depths and sample rates, and then convert to e.g. 16 bit as the very last step. The problem is that squeezing good output from low precision or low sample rates requires more complicated and slower algorithms.

rbanffy 6y ago

Probably not as crisp as 16-bit integers - mantissa is 7 bits, so 8-bits with sign. Clever use of exponents may give some additional range, but I wouldn't be too optimistic. The good thing is that, as any FP number, can represent a very large range of values, so I'd expect percussion and other things with very high-frequency transients to sound nice. My bet is it'll sound "colorful". IEEE float16 should sound better. But I'm no expert and I don't have the time to write something that force a good high dynamic range track to be rounded to the nearest bfloat16 and then expanded back. Also, I don't have gear good enough to hear anything better than CD-grade audio.

klodolph 6y ago

I’m sure you could come up with an application for it, but if you want audio output at some point, half-float sounds like quite a challenge. - The -66dB noise floor is pretty bad, and it accumulates at every step. - 11 bits is probably not enough for filter coefficients. So your filters would likely be running with single precision floats, at least. Even low-cost DSP chips tend to give you a big chunk of bits for your filters. - Naïve oscillator designs would accumulate a lot of error. Back of the envelope calculation, if you wanted an oscillator at C4, you’d likely be around 1/4 tone sharp or flat unless you ran the oscillator at higher precision. I’m definitely of the mind that bit depth is overrated in music. 16 bits is great-for mastered music and simple tweaks. By contrast, from my experiences writing DSP code, it often makes your code simpler and faster to run at higher depths and sample rates, and then convert to e.g. 16 bit as the very last step. The problem is that squeezing good output from low precision or low sample rates requires more complicated and slower algorithms.