ABF1 file writing bug

[swharden]

At present the ABF file writer has a fixed scaling factor (fInstrumentScaleFactor, fSignalGain, fADCProgrammableGain, etc). This causes the ABF writer to crash if ABF values being saved are outside the range supported by the fixed scaling factor. For example, the current code will crash on voltage-clamp ABFs with data greater than +/- 1000 pA.

To correct this issue, the ABF writer will be made smarter by using a custom scaling factor determined by the maximum and minimum data values. This ticket will track progress toward this end.

A new ABF (f1.abf) was added to the data section to test against.

Relevant code (the section where the fixed scale factors are defined) is:

pyABF/src/pyabf/abfWriter.py

Lines 54 to 67 in 59aa70b

	fSignalGain = 1 # always 1
	fADCProgrammableGain = 1 # always 1
	lADCResolution = 2**15 # 16-bit signed = +/- 32768
	fInstrumentScaleFactor = 0.005 # good for -2k to +2k pA scale
	fADCRange = 10
	valueScale = lADCResolution / fADCRange * fInstrumentScaleFactor
	struct.pack_into('i', data, 252, lADCResolution)
	struct.pack_into('f', data, 244, fADCRange)
	for i in range(16):
	struct.pack_into('f', data, 922+i*4, fInstrumentScaleFactor)
	struct.pack_into('f', data, 1050+i*4, fSignalGain)
	struct.pack_into('f', data, 730+i*4, fADCProgrammableGain)
	struct.pack_into('8s', data, 602+i*8, b'pA')

note: the original discussion about ABF1 file writing was at: #60 (comment)

[swharden]

This issue has been corrected in pyABF 2.0.31 (live now)

pip install --upgrade pyabf