def __call__(self, video: FieldFile):
# Get the MIME type string of this video.
videoContentType = magic.from_buffer(video.read(), mime=True)
# Point the cursor to the beginning of the file.
video.seek(0)
if videoContentType not in self.allowedContentTypes:
raise ValidationError(
'The file type %(contentType)s is not supported.',
params={'contentType': videoContentType})
def calculate_file_hash(file: FieldFile) -> str:
# Together the MemoryFileUploadHandler and TemporaryFileUploadHandler
# provide Django’s default file upload behavior of reading small files
# into memory and large ones onto disk.
# If a file is large file will be an instance of TemporaryUploadedFile,
# TemporaryUploadedFile.temporary_file_path() returns the full path to the temporary uploaded file.
# If a file is small file will be an instance of InMemoryUploadedFile.
file_hash = sha256()
# Returns True if the uploaded file is big enough to require reading in multiple chunks.
# By default this will be any file larger than 2.5 megabytes, but that’s configurable;
if not file.multiple_chunks():
file_hash.update(file.read())
else:
for chunk in file.chunks():
file_hash.update(chunk)
return file_hash.hexdigest()
def setup_work_dir(file: FieldFile) -> Tuple[TemporaryDirectory, Path]:
"""Create a temporary directory as working directory and make the source file locally available."""
temp_dir = TemporaryDirectory()
try:
source_file_path = Path(file.path)
except (AttributeError, NotImplementedError):
source_file_path = Path(temp_dir.name) / Path(file.name).name
with source_file_path.open('wb') as fp:
if file.multiple_chunks():
for chunk in file.chunks():
fp.write(chunk)
else:
fp.write(file.read())
return temp_dir, source_file_path
def get_preview(file: FieldFile) -> bytes:
"""
Retrieves frame from the middle of video as preview image
"""
temp_filename = os.path.join(tempfile.gettempdir(), str(uuid.uuid4()))
with open(temp_filename, "wb") as _file:
file.seek(0)
_file.write(file.read())
capture = cv2.VideoCapture(temp_filename)
frame_count = int(capture.get(cv2.CAP_PROP_FRAME_COUNT))
capture.set(cv2.CAP_PROP_POS_FRAMES, round(frame_count / 2))
capture.grab()
retval, img = capture.retrieve(0)
image_bytes = cv2.imencode("temp/preview.jpg", img)[1].tobytes()
capture.release()
os.remove(temp_filename)
return image_bytes
def _get_dict_reader(self, field_file: FieldFile):
as_str = field_file.read().decode('utf-8')
dict_reader = DictReader(StringIO(as_str),
delimiter=',',
quotechar='"')
return dict_reader
def read_in_chunks(file: FieldFile, chunk_size=65536):
while True:
data = file.read(chunk_size)
if not data:
break
yield data
