codekingpro/portable-devtools

1#
2# The Python Imaging Library.
3# $Id$
4#
5# MPEG file handling
6#
7# History:
8#       95-09-09 fl     Created
9#
10# Copyright (c) Secret Labs AB 1997.
11# Copyright (c) Fredrik Lundh 1995.
12#
13# See the README file for information on usage and redistribution.
14#
15from __future__ import annotations
16
17from . import Image, ImageFile
18from ._binary import i8
19from ._typing import SupportsRead
20
21#
22# Bitstream parser
23
24
25class BitStream:
26    def __init__(self, fp: SupportsRead[bytes]) -> None:
27        self.fp = fp
28        self.bits = 0
29        self.bitbuffer = 0
30
31    def next(self) -> int:
32        return i8(self.fp.read(1))
33
34    def peek(self, bits: int) -> int:
35        while self.bits < bits:
36            self.bitbuffer = (self.bitbuffer << 8) + self.next()
37            self.bits += 8
38        return self.bitbuffer >> (self.bits - bits) & (1 << bits) - 1
39
40    def skip(self, bits: int) -> None:
41        while self.bits < bits:
42            self.bitbuffer = (self.bitbuffer << 8) + i8(self.fp.read(1))
43            self.bits += 8
44        self.bits = self.bits - bits
45
46    def read(self, bits: int) -> int:
47        v = self.peek(bits)
48        self.bits = self.bits - bits
49        return v
50
51
52def _accept(prefix: bytes) -> bool:
53    return prefix.startswith(b"\x00\x00\x01\xb3")
54
55
56##
57# Image plugin for MPEG streams.  This plugin can identify a stream,
58# but it cannot read it.
59
60
61class MpegImageFile(ImageFile.ImageFile):
62    format = "MPEG"
63    format_description = "MPEG"
64
65    def _open(self) -> None:
66        assert self.fp is not None
67
68        s = BitStream(self.fp)
69        if s.read(32) != 0x1B3:
70            msg = "not an MPEG file"
71            raise SyntaxError(msg)
72
73        self._mode = "RGB"
74        self._size = s.read(12), s.read(12)
75
76
77# --------------------------------------------------------------------
78# Registry stuff
79
80Image.register_open(MpegImageFile.format, MpegImageFile, _accept)
81
82Image.register_extensions(MpegImageFile.format, [".mpg", ".mpeg"])
83
84Image.register_mime(MpegImageFile.format, "video/mpeg")
85