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Nomalize and convert Float to Integer

Posted on 2013-05-13
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Last Modified: 2013-05-21
Hello,
  I have the following arrays:

const
  cMaxSampleDuration = 420;

var
    MyDoubleArray: array[0..5, 0..cMaxSampleDuration -1] of Double;
    MyIntegerArray: array[0..5, 0..cMaxSampleDuration -1] of Integer;

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with the following function i convert the float number to integers:

  for Channel := 0 to 6 -1 do
  for Samples := 0 to cMaxSampleDuration -1 do
    MyIntegerArray[Channel, Samples] := Round(Frac(MyDoubleArray[Channel, Samples]) * 200000);

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Comment: Since it's a wave i care only for the  fractional part of the float not the integer.

Now, i want to normalize the array so the scale up every channel to be in the same range.
(Like normilizing a waveform, in this case 6 channels/waves)

Thank you
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Comment
Question by:chmichael
  • 2
3 Comments
 
LVL 28

Expert Comment

by:Sinisa Vuk
ID: 39163176
Must pre-scan all data and get maximum value for each channel. Then go upscale data.
const
  cMaxSampleDuration = 420;

var
    MyDoubleArray: array[0..5, 0..cMaxSampleDuration -1] of Double;
    MyIntegerArray: array[0..5, 0..cMaxSampleDuration -1] of Integer;
    Channel, Samples: Integer;

    ScaleValue: array[0..5] of Double;
    AllMaxValue, GlobalScale: Double;
....
  //get scale values
  AllMaxValue := 0;
  for Channel := 0 to 6 -1 do
  begin
    ScaleValue[Channel] := 0;
    for Samples := 0 to cMaxSampleDuration -1 do
    begin
      if MyDoubleArray[Channel, Samples]>ScaleValue[Channel] then
        ScaleValue[Channel] := MyDoubleArray[Channel, Samples];
    end;
    if ScaleValue[Channel]>AllMaxValue then
      AllMaxValue := ScaleValue[Channel];
  end;

  //scaling
  GlobalScale := 200000;
  for Channel := 0 to 6 -1 do
  begin
    for Samples := 0 to cMaxSampleDuration -1 do
      MyIntegerArray[Channel, Samples] :=
        Round(Frac(MyDoubleArray[Channel, Samples] * AllMaxValue / ScaleValue[Channel]) * GlobalScale);
  end;

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0
 

Author Comment

by:chmichael
ID: 39167465
It doesn't work with negative numbers! Can you take a look ?

Thank you
0
 
LVL 28

Accepted Solution

by:
Sinisa Vuk earned 2000 total points
ID: 39177624
Try this modification:
//get scale values
  AllMaxValue := 0;
  for Channel := 0 to 6 -1 do
  begin
    ScaleValue[Channel] := 0;
    for Samples := 0 to cMaxSampleDuration -1 do
    begin
      if Abs(MyDoubleArray[Channel, Samples])>Abs(ScaleValue[Channel]) then
        ScaleValue[Channel] := MyDoubleArray[Channel, Samples];
    end;
    if Abs(ScaleValue[Channel])>Abs(AllMaxValue) then
      AllMaxValue := ScaleValue[Channel];
  end;

  //scaling
  GlobalScale := 200000;
  for Channel := 0 to 6 -1 do
  begin
    for Samples := 0 to cMaxSampleDuration -1 do
      MyIntegerArray[Channel, Samples] :=
        Round(Frac(MyDoubleArray[Channel, Samples] * Abs(AllMaxValue) / Abs(ScaleValue[Channel])) * GlobalScale);
  end;

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