channel default volume is unusual about m5unified

[belm0]

I have no doubt that multi-channel, 16-bit sound can be handled well within fixed-point, 32-bit operations. (The PlayStation or early consoles and sound cards had no floating point hardware, etc.)

To start, 32-bit dynamic range is really not needed for volume.

[lovyan03]

@belm0
Thank you for your important input.
I apologize for any inconvenience caused by my ignorance of standard audio designs thinking.
I will review the volume settings in the next version and set the default channel volume to 255.

By the way, the volume value is calculated internally as a square ( volume ^ 2 ) . In other words, the output varies quadratically.
Both master volume and channel volume.
Do you have any opinions or generalizations about this process?

[belm0]

By the way, the volume value is calculated internally as a square ( volume ^ 2 )

I was going to say something about this requiring a 64-bit intermediate value for each sample unless some optimizations are done, but then I realized that the code is using a float buffer. I'm a little surprised because float is not very fast on ESP32, so I guess this is a luxury sound library 😉

[lovyan03]

@belm0
Oh.. yes, I was reluctant to use floats, but I couldn't think of a better way.
In fact, I've been racking my brains because I later realized that the float operation is even slower in ESP32C3…😨

[mdxs]

This ticket can be closed as resolved. Suggesting to create a new ticket if there is a reason to keep track of looking into the use of integers instead of floats (as discussed a bit in comments to this ticket).