Added exiftool
This commit is contained in:
Rhet Turnbull
239
osxphotos/exiftool.py
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239
osxphotos/exiftool.py
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""" Yet another simple exiftool wrapper
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I rolled my own for following reasons:
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1. I wanted something under MIT license (best alternative was licensed under GPL/BSD)
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2. I wanted singleton behavior so only a single exiftool process was ever running
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If these aren't important to you, I highly recommend you use Sven Marnach's excellent
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pyexiftool: https://github.com/smarnach/pyexiftool which provides more functionality """
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import json
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import logging
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import os
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import subprocess
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import sys
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from functools import lru_cache
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from .utils import _debug
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# exiftool -stay_open commands outputs this EOF marker after command is run
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EXIFTOOL_STAYOPEN_EOF = "{ready}"
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EXIFTOOL_STAYOPEN_EOF_LEN = len(EXIFTOOL_STAYOPEN_EOF)
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@lru_cache(maxsize=1)
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def get_exiftool_path():
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""" return path of exiftool, cache result """
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result = subprocess.run(["which", "exiftool"], stdout=subprocess.PIPE)
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exiftool_path = result.stdout.decode("utf-8")
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if _debug():
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logging.debug("exiftool path = %s" % (exiftool_path))
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if exiftool_path:
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return exiftool_path.rstrip()
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else:
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raise FileNotFoundError(
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"Could not find exiftool. Please download and install from "
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"https://exiftool.org/"
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)
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class _ExifToolProc:
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""" Runs exiftool in a subprocess via Popen
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Creates a singleton object """
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def __new__(cls, *args, **kwargs):
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""" create new object or return instance of already created singleton """
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if not hasattr(cls, "instance") or not cls.instance:
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cls.instance = super().__new__(cls)
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return cls.instance
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def __init__(self, exiftool=None):
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""" construct _ExifToolProc singleton object or return instance of already created object
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exiftool: optional path to exiftool binary (if not provided, will search path to find it) """
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if hasattr(self, "_process_running") and self._process_running:
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# already running
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if exiftool is not None:
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logging.warning(
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f"exiftool subprocess already running, "
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f"ignoring exiftool={exiftool}"
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)
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return
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if exiftool:
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self._exiftool = exiftool
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else:
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self._exiftool = get_exiftool_path()
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self._process_running = False
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self._start_proc()
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@property
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def process(self):
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""" return the exiftool subprocess """
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if self._process_running:
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return self._process
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else:
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raise ValueError("exiftool process is not running")
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@property
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def pid(self):
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""" return process id (PID) of the exiftool process """
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return self._process.pid
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@property
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def exiftool(self):
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""" return path to exiftool process """
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return self._exiftool
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def _start_proc(self):
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""" start exiftool in batch mode """
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if self._process_running:
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logging.warning("exiftool already running: {self._process}")
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return
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# open exiftool process
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self._process = subprocess.Popen(
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[
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self._exiftool,
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"-stay_open", # keep process open in batch mode
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"True", # -stay_open=True, keep process open in batch mode
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"-@", # read command-line arguments from file
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"-", # read from stdin
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"-common_args", # specifies args common to all commands subsequently run
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"-n", # no print conversion (e.g. print tag values in machine readable format)
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"-G", # print group name for each tag
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],
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stdin=subprocess.PIPE,
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stdout=subprocess.PIPE,
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stderr=subprocess.DEVNULL,
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)
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self._process_running = True
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def _stop_proc(self):
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""" stop the exiftool process if it's running, otherwise, do nothing """
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if not self._process_running:
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logging.warning("exiftool process is not running")
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return
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self._process.stdin.write(b"-stay_open\n")
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self._process.stdin.write(b"False\n")
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self._process.stdin.flush()
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try:
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self._process.communicate(timeout=5)
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except subprocess.TimeoutExpired:
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logging.warning(
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f"exiftool pid {self._process.pid} did not exit, killing it"
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)
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self._process.kill()
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self._process.communicate()
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del self._process
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self._process_running = False
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def __del__(self):
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self._stop_proc()
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class ExifTool:
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""" Basic exiftool interface for reading and writing EXIF tags """
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def __init__(self, file, exiftool=None):
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self.file = file
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self.data = {}
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self._exiftoolproc = _ExifToolProc(exiftool=exiftool)
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self._process = self._exiftoolproc.process
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self._read_exif()
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def setvalue(self, tag, value):
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""" Set tag to value(s)
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if value is None, will delete tag """
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if value is None:
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value = ""
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command = f"-{tag}={value}"
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self.run_commands(command)
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def addvalues(self, tag, *values):
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""" Add one or more value(s) to tag
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If more than one value is passed, each value will be added to the tag
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Notes: exiftool may add duplicate values for some tags so the caller must ensure
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the values being added are not already in the EXIF data
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For some tags, such as IPTC:Keywords, this will add a new value to the list of keywords,
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but for others, such as EXIF:ISO, this will literally add a value to the existing value.
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It's up to the caller to know what exiftool will do for each tag
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If setvalue called before addvalues, exiftool does not appear to add duplicates,
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but if addvalues called without first calling setvalue, exiftool will add duplicate values
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"""
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if not values:
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raise ValueError("Must pass at least one value")
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command = []
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for value in values:
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if value is None:
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raise ValueError("Can't add None value to tag")
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command.append(f"-{tag}+={value}")
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if command:
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self.run_commands(*command)
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def run_commands(self, *commands, no_file=False):
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""" run commands in the exiftool process and return result
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no_file: (bool) do not pass the filename to exiftool (default=False)
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by default, all commands will be run against self.file
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use no_file=True to run a command without passing the filename """
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if not hasattr(self, "_process") or not self._process:
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raise ValueError("exiftool process is not running")
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if not commands:
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raise TypeError("must provide one or more command to run")
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filename = os.fsencode(self.file) if not no_file else b""
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command_str = (
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b"\n".join([c.encode("utf-8") for c in commands])
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+ b"\n"
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+ filename
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+ b"\n"
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+ b"-execute\n"
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)
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if _debug():
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logging.debug(command_str)
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# send the command
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self._process.stdin.write(command_str)
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self._process.stdin.flush()
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# read the output
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output = b""
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while EXIFTOOL_STAYOPEN_EOF not in str(output):
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output += self._process.stdout.readline().strip()
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return output[:-EXIFTOOL_STAYOPEN_EOF_LEN]
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@property
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def pid(self):
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""" return process id (PID) of the exiftool process """
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return self._process.pid
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@property
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def version(self):
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""" returns exiftool version """
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ver = self.run_commands("-ver", no_file=True)
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return ver.decode("utf-8")
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def json(self):
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""" return JSON dictionary from exiftool as dict """
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json_str = self.run_commands("-json")
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if json_str:
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return json.loads(json_str)
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else:
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return None
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def _read_exif(self):
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""" read exif data from file """
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json = self.json()
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self.data = {k: v for k, v in json[0].items()}
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def __str__(self):
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str_ = f"file: {self.file}\nexiftool: {self._exiftoolproc._exiftool}"
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return str_
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