|
|
|
|
|
|
by raphlinus
3370 days ago
|
|
|
An example of the linear-interpolated lookup table approach using fixed-point math is the sine generation[0] in my music synthesizer. It generates a table of 1024 entries, then lerps between those. This gives you precision beyond the least perceptible audio error, and is pretty fast. When I first wrote that code, I was targeting 32 bit ARM, with possibly very weak floating point units. These days, on the types of chips you'd see in phones (or computers in the $9-$40 range like rpi 3), the floating point calculation is _so_ fast (especially with simd) that the cost of the memory lookup starts dominating. So, the NEON implementation computes 4 sin values in a gulp, using a floating point polynomial approximation about the same precision as above[1]. [0] https://github.com/google/music-synthesizer-for-android/blob... [1] https://github.com/google/music-synthesizer-for-android/blob... |
|
|