0

I'm trying to loop over an extremely large signed 24 bit little endian binary file to convert to decimal

this is the code i'm currently using

def unpack_24bit(bytes):
    return bytes[0] | (bytes[1] << 8) | (bytes[2] << 16)

f=open('1.raw','rb')

#Read in the data as a byte array (8-bit array)
ba = bytearray(f.read())[enter image description here][1]
length = len(ba)
print('N-bytes=',length)
#Since the data is in 24bits, convert three bits at a time to a 24 signed bit
nvals = int(length/3);
print('N-recordings for 24bits (3-byte data)=',nvals)
dat = np.zeros(nvals)

for i in range(0,nvals):
    dat[i] = (unpack_24bit(struct.unpack('<bbb', ba[3*i:3+i*3])))

The result it gives is seen here [1]: https://i.stack.imgur.com/FfWPn.png its not quite correct

It should appear as a square waveform

any suggestions?

jaketomo
  • 1
  • 1

1 Answers1

0

Figured it out and will post here incase someone has a similar issue.

first 3 bytes were unsigned and last byte as signed

def unpack_24bit(bytes):
    return bytes[0] | (bytes[1] << 8) | (bytes[2]) << 16

f=open('TX_Testing_201202_20201202_044904.0000000_Other_1_1 - Copy.raw','rb')

#Read in the data as a byte array (8-bit array)
ba = bytearray(f.read())
length = len(ba)
print('N-bytes=',length)
#Since the data is in 24bits, convert three bits at a time to a 24 signed bit
nvals = int(length/3);
print('N-recordings for 24bits (3-byte data)=',nvals)
dat = np.zeros(nvals)

for i in range(0,nvals):
    dat[i] = (unpack_24bit(struct.unpack('<BBb', ba[3*i:3+i*3]))*scale+offset+nulling)
jaketomo
  • 1
  • 1