Video Metadata Question

[snippsat]

the basic approach I need is to open the file in binary mode and read a certain amount of bytes, right?

That's a start,read some data let say 1000 bytes at time and look at the data.
Example.

with open('planet.mkv', 'rb') as f:
    data = f.read()[:1000]
    print(data)

When doing this test i can see that some of the meta data is in clear text.
To take of some data.

import re

with open('planet.mkv', 'rb') as f:
    data = f.read()[:3000]
    #print(data)

rate = re.search(b'bitrate=\d+', data)
print(rate.group())
vbv_max = re.search(b'vbv_maxrate=\d+', data)
print(vbv_max.group())

Output:
b'bitrate=2250'
b'vbv_maxrate=2812'

From bytes to string(this Unicode bye default) in Python 3.

>>> b = b'bitrate=2250'
>>> type(b)
<class 'bytes'>

>>> s = b.decode() # same as decode('utf-8')
>>> s
'bitrate=2250'
>>> type(s)
<class 'str'>