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#!/usr/bin/env python
import struct
import os
ETI_FORMAT_RAW = "RAW"
ETI_FORMAT_STREAMED = "STREAMED"
ETI_FORMAT_FRAMED = "FRAMED"
class EtiReaderException(Exception):
pass
class EtiReader(object):
def __init__(self, filename):
self.filename = filename
self.fd = open(filename, "rb")
self.fmt = self.discover_filetype()
print("EtiReader reading {0}, discovered type {1}".format(filename, self.fmt))
def discover_filetype(self):
self.fd.seek(0)
sync = False
i = 0
while True:
sync = self.check_sync()
if not sync:
i = i + 1
self.fd.seek(i)
else:
break
if i == 0:
self.fd.seek(0)
return ETI_FORMAT_RAW
elif i == 2:
self.fd.seek(0)
return ETI_FORMAT_STREAMED
elif i == 6:
self.fd.seek(4)
return ETI_FORMAT_FRAMED
else:
print("ETI File not aligned, supposing RAW!")
return ETI_FORMAT_RAW
def __iter__(self):
while True:
n = self.next()
if n == "":
break
else:
yield n
def next(self):
if self.fmt == ETI_FORMAT_RAW:
etiframe = self.fd.read(6144)
if etiframe == "":
raise EtiReaderException("Unable to read frame")
return etiframe
elif self.fmt == ETI_FORMAT_FRAMED or self.fmt == ETI_FORMAT_STREAMED:
framesize_pack = self.fd.read(2)
if len(framesize_pack) < 2:
raise EtiReaderException("Unable to read frame size")
framesize = struct.unpack("H", framesize_pack)[0]
if framesize == 0 or framesize > 6144:
raise EtiReaderException("Framesize: {0}".format(framesize))
if not self.check_sync():
raise EtiReaderException("Unable to read sync")
self.fd.seek(-2, os.SEEK_CUR)
frame = self.fd.read(framesize+2)
if len(frame) < framesize:
raise EtiReaderException("Unable to read frame")
return frame
def check_sync(self):
here = self.fd.tell()
sync_pack = self.fd.read(4)
self.fd.seek(here)
sync = struct.unpack("I", sync_pack)[0]
return sync == 0x49c5f8ff or sync == 0xb63a07ff
if __name__ == "__main__":
def etireadertest(reader):
i = 0
for frame in reader:
allframes.append(frame)
print("Frame {0}, length {1}".format(
i, len(frame)))
i += 1
if i > 10:
break
allframes = []
etireadertest(EtiReader("buddard.eti"))
allframes = []
etireadertest(EtiReader("streamed.eti"))
allframes = []
etireadertest(EtiReader("funk.eti"))
allframes = []
etireadertest(EtiReader("funk.raw.eti"))
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