Converting double values file to 2 byte per sample.

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Hi,
I have a .txt file with 128 x 11900 vlaues. These values are doubles ranging from -0.00023462 to +1.0719. I need to convert them to 2 bytes per sample and store in a .bin file. I am not getting how to do it. I tried using the 'fread' function of matlab but all I am able to do is convert each sample to 8 bytes(double precision). Is there a way I can convert each sample into 2 bytes each?

Accepted Answer

Walter Roberson
Walter Roberson on 16 Jul 2020
two_bytes = uint16(floor(YourMatrix/1.636E-5)+15);
and fwrite() as uint16 .
reconstructed = (double(two_bytes) - 15) * 1.636E-5
the reconstruction error can be up to 1.636E-5 . You can reduce the average reconstruction error by using round() instead of floor(), but then you have to work on the boundary condition (the +15 or -15) (though there happens to be just enough slack room in the representation so that it is not a problem.)
  4 Comments
ratnesh pandey
ratnesh pandey on 17 Jul 2020
"Now for any one sample, the representation in 2^16th units is floor of (the sample divided by delta). Apply that to the lower bound of your data and you get -15"
you mean -14? floor(-0.00023462/1.636E-5)

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More Answers (1)

James Tursa
James Tursa on 16 Jul 2020
If you want a two byte floating point representation you can use half precision. E.g.,
This is one of the standard floating point formats, but will result in less precision than Walter's method because some of the bits are used for sign and exponent.

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