main.dart

import 'dart:typed_data';
import 'dart:io';


class Half {
  static Float32List ToFloat32(ByteData buffer) {

    var f32Buffer = ByteData(buffer.lengthInBytes * 2);
    
    for(int i = 0; i < buffer.lengthInBytes; i+=2) {
        var half = buffer.getUint16(i, Endian.little);     
        // get sign by AND 0x800
        var sign = half & 0x8000;
        // LS sign by 16 bits
        sign = sign << 16;
        // RS half by 10 to discard mantissa
        var exp = half >> 10;
        // mask out sign bit by AND 0x1F (0001 1111) 
        exp = exp & 0x1F;
        // convert exp from 5-bit offset-binary to 8-bit offset-binary adding 0111 0000 = 0x70
        exp = exp + 0x70;
        // LS exp by 23
        exp = exp << 23;
        // mask out sign/exp by AND 0x03FF (0000 0011 1111 1111)
        var mant = half & 0x03FF;
        // convert mant from 10-bit offset-binary to 23-bit offset-binary by shifting left 13
        mant = mant << 13;

        f32Buffer.setInt32(i * 2, sign + exp + mant, Endian.little);
      }
      return Float32List.view(f32Buffer.buffer);
  }
}

void main() async {
  var test = await File('test_mono_16b_le.wav').readAsBytes();
  print(test.buffer.asByteData().getUint16(0x32, Endian.little)); // 4A00 ->  74
  print(Half.ToFloat32(test.buffer.asByteData(0x32, 2)).buffer.asByteData().getFloat32(0));
}