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samrushingianare
samrushing
authored and
ianare
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initial HEIC support. (#89)
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‎exifread/__init__.py

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Original file line numberDiff line numberDiff line change
@@ -6,6 +6,7 @@
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from .classes import *
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from .tags import *
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from .utils import ord_
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from .heic import HEICExifFinder
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__version__ = '2.1.2'
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@@ -39,6 +40,10 @@ def process_file(f, stop_tag=DEFAULT_STOP_TAG, details=True, strict=False, debug
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endian = f.read(1)
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f.read(1)
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offset = 0
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elif data[4:12] == b'ftypheic':
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f.seek(0)
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heic = HEICExifFinder (f)
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offset, endian = heic.find_exif()
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elif data[0:2] == b'\xFF\xD8':
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# it's a JPEG file
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logger.debug("JPEG format recognized data[0:2]=0x%X%X", ord_(data[0]), ord_(data[1]))

‎exifread/heic.py

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,244 @@
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# -*- Mode: Python -*-
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# Find Exif data in an HEIC file.
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# As of 2019, the latest standard seems to be "ISO/IEC 14496-12:2015"
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# There are many different related standards. (quicktime, mov, mp4, etc...)
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# See https://en.wikipedia.org/wiki/ISO_base_media_file_format for more details.
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# We parse just enough of the iso format to locate the Exif data in the file.
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# Inside the 'meta' box are two directories we need:
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# 1) the 'iinf' box contains 'infe' records, we look for the item_ID for 'Exif'.
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# 2) once we have the item_ID, we find a matching entry in the 'iloc' box, which
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# gives us position and size information.
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import struct
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from .exif_log import get_logger
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logger = get_logger()
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class WrongBox (Exception):
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pass
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class NoParser (Exception):
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pass
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class BoxVersion (Exception):
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pass
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class BadSize (Exception):
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pass
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class Box:
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def __init__ (self, name):
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self.name = name
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def __repr__ (self):
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return "<box '%s'>" % (self.name,)
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class HEICExifFinder:
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def __init__ (self, file):
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self.file = file
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def get (self, nbytes):
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r = self.file.read (nbytes)
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if not r:
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raise EOFError
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else:
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return r
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def get16 (self):
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return struct.unpack ('>H', self.get (2))[0]
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def get32 (self):
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return struct.unpack ('>L', self.get (4))[0]
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def get64 (self):
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return struct.unpack ('>Q', self.get (8))[0]
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def get_int4x2 (self):
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n = struct.unpack ('>B', self.get(1))[0]
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n0 = n >> 4
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n1 = n & 0xf
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return n0, n1
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# some fields have variant-sized data.
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def get_int (self, size):
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if size == 2:
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return self.get16()
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elif size == 4:
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return self.get32()
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elif size == 8:
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return self.get64()
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elif size == 0:
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return 0
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else:
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raise BadSize (size)
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def get_string (self):
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r = []
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while 1:
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ch = self.get (1)
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if ch == b'\x00':
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break
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else:
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r.append (ch)
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return b''.join (r)
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def next_box (self, depth=0):
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pos = self.file.tell()
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size = self.get32()
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kind = self.get(4).decode('ascii')
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b = Box (kind)
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if size == 0:
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# signifies 'to the end of the file', we shouldn't see this.
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raise NotImplementedError
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elif size == 1:
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# 64-bit size follows type.
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size = self.get64()
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b.size = size - 16
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b.after = pos + size
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else:
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b.size = size - 8
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b.after = pos + size
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b.pos = self.file.tell()
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return b
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def get_full (self, box):
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# iso boxes come in 'old' and 'full' variants. the 'full' variant
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# contains version and flags information.
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vflags = self.get32()
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box.version = vflags >> 24
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box.flags = vflags & 0x00ffffff
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def skip (self, box):
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self.file.seek (box.after)
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def expect_parse (self, name):
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b = self.next_box()
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if b.name == name:
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return self.parse_box (b)
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else:
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raise WrongBox (name, b.name)
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def get_parser (self, box):
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method = 'parse_%s' % (box.name,)
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return getattr (self, method, None)
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def parse_box (self, b):
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probe = self.get_parser (b)
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if probe is None:
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raise NoParser (b.name)
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else:
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probe (b)
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# in case anything is left unread
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self.file.seek (b.after)
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return b
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def parse_ftyp (self, box):
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box.major_brand = self.get(4)
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box.minor_version = self.get32()
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box.compat = []
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size = box.size - 8
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while size > 0:
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box.compat.append (self.get (4))
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size -= 4
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def parse_meta (self, meta):
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self.get_full (meta)
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# this is full of boxes, but not in a predictable order.
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meta.subs = {}
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while self.file.tell() < meta.after:
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box = self.next_box()
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psub = self.get_parser (box)
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if psub is not None:
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psub (box)
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meta.subs[box.name] = box
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else:
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logger.debug("HEIC: skipping %r" % (box,))
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# skip any unparsed data
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self.skip (box)
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def parse_infe (self, box):
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self.get_full (box)
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if box.version >= 2:
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if box.version == 2:
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box.item_ID = self.get16()
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elif box.version == 3:
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box.item_ID = self.get32()
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box.item_protection_index = self.get16()
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box.item_type = self.get(4)
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box.item_name = self.get_string()
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# ignore the rest
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else:
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box.item_type = ''
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def parse_iinf (self, box):
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self.get_full (box)
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count = self.get16()
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box.exif_infe = None
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for _ in range (count):
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infe = self.expect_parse ('infe')
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if infe.item_type == b'Exif':
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logger.debug("HEIC: found Exif 'infe' box")
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box.exif_infe = infe
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break
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def parse_iloc (self, box):
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self.get_full (box)
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s0, s1 = self.get_int4x2()
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s2, s3 = self.get_int4x2()
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box.offset_size = s0
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box.length_size = s1
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box.base_offset_size = s2
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box.index_size = s3
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if box.version < 2:
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box.item_count = self.get16()
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elif box.version == 2:
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box.item_count = self.get32()
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else:
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raise BoxVersion (2, box.version)
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box.locs = {}
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logger.debug("HEIC: %d iloc items" % (box.item_count,))
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for i in range (box.item_count):
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if box.version < 2:
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item_ID = self.get16()
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elif box.version == 2:
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item_ID = self.get32()
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else:
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# notreached
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raise BoxVersion (2, box.version)
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if box.version in (1, 2):
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# ignore construction_method
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_ = self.get16()
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data_reference_index = self.get16()
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box.base_offset = self.get_int (box.base_offset_size)
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extent_count = self.get16()
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extents = []
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for _ in range (extent_count):
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if box.version in (1, 2) and box.index_size > 0:
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extent_index = self.get_int (box.index_size)
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else:
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extent_index = -1
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extent_offset = self.get_int (box.offset_size)
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extent_length = self.get_int (box.length_size)
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extents.append ((extent_offset, extent_length))
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box.locs[item_ID] = extents
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def find_exif (self):
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ftyp = self.expect_parse ('ftyp')
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assert ftyp.major_brand == b'heic'
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assert ftyp.minor_version == 0
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meta = self.expect_parse ('meta')
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item_ID = meta.subs['iinf'].exif_infe.item_ID
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extents = meta.subs['iloc'].locs[item_ID]
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logger.debug("HEIC: found Exif location.")
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# we expect the Exif data to be in one piece.
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assert len(extents) == 1
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pos, size = extents[0]
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# looks like there's a kind of pseudo-box here.
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self.file.seek (pos)
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size1 = self.get32()
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assert self.get(size1)[0:4] == b'Exif'
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offset = self.file.tell()
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endian = self.file.read(1)
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return offset, endian

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