Update python example with header information

Updated the python example to show how the header can be constructed in python and sent along with the data.

Resources/python-example.py

@@ -6,21 +6,34 @@
 # ---- SPECIFY THE SIGNAL PROPERTIES ---- #
 totalDuration = 10   # the total duration of the signal
 numChannels = 4      # number of channels to send
-bufferSize = 500     # size of the data buffer
+numSamples = 500     # size of the data buffer
 Freq = 30000         # sample rate of the signal
 testingValue1 = 100  # high value
 testingValue2= -100  # low value
 
+# ---- DEFINE HEADER VALUES ---- #
+headerSize  = 22 # Specifies that there are 22 bytes in the header
+offset      = 0 # Offset of bytes in this packet; only used for buffers > ~64 kB
+dataType    = 2 # Enumeration value based on OpenCV.Mat data types
+elementSize = 2 # Number of bytes per element. elementSize = 2 for U16
+# Data types:   [ U8, S8, U16, S16, S32, F32, F64 ]
+# Enum value:   [  0,  1,   2,   3,   4,   5,   6 ]
+# Element Size: [  1,  1,   2,   2,   4,   4,   8 ]  
+bytesPerBuffer = numChannels * numSamples * elementSize
+
+header = np.array([offset, bytesPerBuffer], dtype='i4').tobytes() + \
+         np.array([dataType], dtype='i2').tobytes() + \
+         np.array([elementSize, numChannels, numSamples], dtype='i4').tobytes()
+
 # ---- COMPUTE SOME USEFUL VALUES ---- #
-bytesPerBuffer = bufferSize * 2 * numChannels
-buffersPerSecond = Freq / bufferSize
+buffersPerSecond = Freq / numSamples
 bufferInterval = 1 / buffersPerSecond
 
 # ---- GENERATE THE DATA ---- #
-OpenEphysOffset = 32768
-convertedValue1 = OpenEphysOffset+(testingValue1/0.195)
-convertedValue2 = OpenEphysOffset+(testingValue2/0.195)
-intList_1 = (np.ones((int(Freq/2),)) * convertedValue1).astype('uint16')
+OpenEphysOffset = 100
+convertedValue1 = OpenEphysOffset+(testingValue1)
+convertedValue2 = OpenEphysOffset+(testingValue2)
+intList_1 = (np.ones((int(Freq/2),)) * convertedValue1).astype('uint16') # if dataType == 2, use astype('uint16')
 intList_2 = (np.ones((int(Freq/2),)) * convertedValue2).astype('uint16')
 oneCycle = np.concatenate((intList_1, intList_2))
 allData = np.tile(oneCycle, (numChannels, totalDuration)).T
@@ -47,12 +60,12 @@ def currentTime():
 # ---- STREAM DATA ---- #
 while (bufferIndex < totalBytes):
     t1 = currentTime()
-    UDPClientSocket.sendto(bytesToSend[bufferIndex:bufferIndex+bytesPerBuffer], serverAddressPort)
+    rc = UDPClientSocket.sendto(header + bytesToSend[bufferIndex:bufferIndex+bytesPerBuffer], serverAddressPort)
     t2 = currentTime()
-
+    
     while ((t2 - t1) < bufferInterval):
         t2 = currentTime()
-
+    
     bufferIndex += bytesPerBuffer
 
 print("Done")