check if we need to update as in https://github.com/OxWearables/actipy/commit/32fe82f63142bf60fa243f0f486287f599e987e0

[chanshing]

Check whether the below needs to also be updated according to this: OxWearables/actipy@32fe82f

biobankAccelerometerAnalysis/src/accelerometer/java/AxivityReader.java

Lines 174 to 205 in c92193b

	if (rateCode != 0) {
	timestampOffset = buf.getShort(26); // timestamp
	// offset ok
	// if fractional offset, then timestamp offset was
	// artificially
	// modified for backwards-compatibility ...
	// therefore undo this...
	int oldDeviceId = getUnsignedShort(buf, 4);
	if ((oldDeviceId & 0x8000) != 0) {
	sampleFreq = 3200.0 / (1 << (15 - (rateCode & 15)));
	if (USE_PRECISE_TIME) {
	// Need to undo backwards-compatible shim:
	// Take into account how many whole samples
	// the fractional part of timestamp
	// accounts for:
	// relativeOffset = fifoLength -
	// (short)(((unsigned long)timeFractional *
	// AccelFrequency()) >> 16);
	// nearest whole sample
	// whole-sec | /fifo-pos@time
	// | |/
	// [0][1][2][3][4][5][6][7][8][9]
	// use 15-bits as 16-bit fractional time
	fractional = ((oldDeviceId & 0x7fff) << 1);
	// frequency is truncated to int in firmware
	timestampOffset += ((fractional * (int) sampleFreq) >> 16);
	}
	}
	} else {
	sampleFreq = buf.getShort(26);
	// very old format, where pos26 = freq
	}