Chris@38: 
Chris@264: module yetilab.signal.window;
Chris@38: 
Chris@222: vec = load yetilab.vector.vector;
Chris@222: bf = load yetilab.vector.blockfuncs;
Chris@38: 
Chris@263: cosineWindowSymmetric a0 a1 a2 a3 n =
Chris@263:    (n1 = n - 1;
Chris@218:     vec.fromList
Chris@38:        (map do i:
Chris@38:             a0
Chris@263:             - a1 * cos(2 * pi * i / n1)
Chris@263:             + a2 * cos(4 * pi * i / n1)
Chris@263:             - a3 * cos(6 * pi * i / n1)
Chris@263:             done [0..n1]));
Chris@263: 
Chris@263: cosineWindowPeriodic a0 a1 a2 a3 n =
Chris@263:    (vec.fromList
Chris@263:        (map do i:
Chris@263:             a0
Chris@38:             - a1 * cos(2 * pi * i / n)
Chris@38:             + a2 * cos(4 * pi * i / n)
Chris@262:             - a3 * cos(6 * pi * i / n)
Chris@263:             done [0..n-1]));
Chris@38:                   
Chris@263: cosineWindow a0 a1 a2 a3 sampling n =
Chris@263:     case sampling of 
Chris@263:     Symmetric (): cosineWindowSymmetric;
Chris@263:     Periodic (): cosineWindowPeriodic;
Chris@263:     esac a0 a1 a2 a3 n;
Chris@263: 
Chris@265: bartlettSymmetric n =
Chris@265:     if n < 2 then vec.ones n
Chris@265:     else
Chris@265:         vec.fromList
Chris@265:            (n1 = n - 1;
Chris@265:             h = int (n1 / 2);
Chris@265:             concat [
Chris@265:                 map do i:
Chris@265:                     2 * i / n1
Chris@265:                     done [0..h],
Chris@265:                 map do i:
Chris@265:                     2 - (2 * i / n1)
Chris@265:                     done [h+1..n1]
Chris@265:                 ]);
Chris@265:     fi;
Chris@265: 
Chris@265: bartlettPeriodic n = 
Chris@265:     if n < 2 then vec.ones n
Chris@265:     else
Chris@265:         vec.slice (bartlettSymmetric (n+1)) 0 n;
Chris@265:     fi;
Chris@265: 
Chris@265: bartlett sampling =
Chris@265:     case sampling of
Chris@265:     Symmetric (): bartlettSymmetric;
Chris@265:     Periodic (): bartlettPeriodic;
Chris@265:     esac;
Chris@265: 
Chris@263: hann = cosineWindow 0.5 0.5 0.0 0.0;
Chris@263: hamming = cosineWindow 0.54 0.46 0.0 0.0;
Chris@263: blackman = cosineWindow 0.42 0.50 0.08 0.0;
Chris@263: nuttall = cosineWindow 0.355768 0.487396 0.144232 0.012604;
Chris@263: blackmanNuttall = cosineWindow 0.3635819 0.4891775 0.1365995 0.0106411;
Chris@263: blackmanHarris = cosineWindow 0.35875 0.48829 0.14128 0.01168;
Chris@263: 
Chris@218: boxcar = vec.consts 0.5;
Chris@38: 
Chris@265: windowFunction type options =
Chris@263:    (var sampling = Periodic ();
Chris@263:     for options \case of
Chris@263:         Symmetric s: if s then sampling := Symmetric () fi
Chris@263:         esac;
Chris@263:     case type of
Chris@263:     Hann (): hann sampling;
Chris@263:     Hamming (): hamming sampling;
Chris@263:     Blackman (): blackman sampling;
Chris@263:     Nuttall (): nuttall sampling;
Chris@263:     BlackmanNuttall (): blackmanNuttall sampling;
Chris@263:     BlackmanHarris (): blackmanHarris sampling;
Chris@263:     Boxcar (): boxcar;
Chris@265:     Bartlett (): bartlett sampling;
Chris@263:     esac);
Chris@263: 
Chris@49: windowed windowFunc frames =
Chris@43:     case frames of
Chris@43:         []: frames;
Chris@43:          _: (first = head frames;
Chris@218:              window = windowFunc (vec.length first);
Chris@43:              map (bf.multiply window) frames);
Chris@43:     esac;
Chris@43: 
Chris@38: {
Chris@263: cosineWindow,
Chris@263: hann = hann (Periodic ()),
Chris@263: hamming = hamming (Periodic ()), 
Chris@263: blackman = blackman (Periodic ()), 
Chris@263: nuttall = nuttall (Periodic ()), 
Chris@263: blackmanNuttall = blackmanNuttall (Periodic ()), 
Chris@263: blackmanHarris = blackmanHarris (Periodic ()),
Chris@265: boxcar,
Chris@265: bartlett = bartlett (Periodic ()), 
Chris@263: windowFunction,
Chris@263: windowed
Chris@38: };
Chris@38: