BioSemi test files - output

[achtzehn]

Dear forum readers,

I'm currently trying to implement a reading function for Matlab to evaluate BDF files.
I've used the provided test files (Newtest17-*.bdf) from the website.
The output looks like a sine wave, with high point at approx. -1.1 and low point at approx. -1.55.
This is after I multiplied the values I got from the file with the gain of the channel.

Is this output correct?

My read function looks somewhat like this:

Code: Select all

union __int24 {struct _bytes {byte byte0;
                             byte byte1;
                             byte byte2;
                             byte byte3;
                             } BYTES;
                int value;
                };

__int24 buffer;


	for (i=0; i < nRecords; i++) {
		...forwarding to the channelposition

        for (j=0;j<sampleRate;j++)
        {
            fread(&buffer.BYTES.byte1, 1, 1, file);
            fread(&buffer.BYTES.byte2, 1, 1, file);
            fread(&buffer.BYTES.byte3, 1, 1, file);
            buffer.value<<8;
            output[(i*sampleRate)+j] = buffer.value;
        }
	}