`Track index out of range` Error When Initial MKVTrack

[Masterain98]

Describe the bug

When adapting pymkv2 from pymkv library, I notice that when initialing an MKVTrack from an existing file, an IndexError: track index out of range error will occur.

To Reproduce

My source code:
https://github.com/Masterain98/PlexMuxy/blob/a0e9c9fab409667a3daaf7f3a34ad7befaa1b617/main.py#L107-L115

---

Minimum reproduce:

    mkv = pymkv.MKVFile("./sample.mkv", mkvmerge_path=MKVMerge)
    mkv.add_track(pymkv.MKVTrack("./sample.JPSC.ass", mkvmerge_path=MKVMerge))

Expected behavior

MKVTrack can be created, separated, and added to MKVFile. This can be achieved in the old pymkv library without any error.

Screenshots

Traceback (most recent call last):
  File "C:\Users\i\Documents\GitHub\pymkv2\simple_tests\simple_test.py", line 11, in <module>
    process_file()
  File "C:\Users\i\Documents\GitHub\pymkv2\simple_tests\simple_test.py", line 8, in process_file
    mkv.add_track(pymkv.MKVTrack("./sample.JPSC.ass", mkvmerge_path=MKVMerge))
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\i\Documents\GitHub\pymkv2\pymkv\MKVTrack.py", line 145, in __init__
    self.file_path = file_path
    ^^^^^^^^^^^^^^
  File "C:\Users\i\Documents\GitHub\pymkv2\pymkv\MKVTrack.py", line 218, in file_path
    self.track_id = 0
    ^^^^^^^^^^^^^
  File "C:\Users\i\Documents\GitHub\pymkv2\pymkv\utils.py", line 98, in wrapper
    return method(self, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\i\Documents\GitHub\pymkv2\pymkv\MKVTrack.py", line 289, in track_id
    raise IndexError(msg)
IndexError: track index out of range

Software (please complete the following information):

• OS: Windows 10 22H2
• MKVToolNix v88

[Masterain98]

Looks like the issue comes from here:

pymkv2/pymkv/MKVTrack.py

Lines 286 to 287 in 51f73ea

	tracks = self._info_json.get("tracks", [])
	if not 0 <= track_id < len(tracks):

For new initialed MKVTrack, len(tracks) will always be zero, because _info_json is {}

pymkv2/pymkv/MKVTrack.py

Line 143 in 51f73ea

self._info_json: dict[str, Any] = existing_info or {}

[GitBib]

The MKVTrack class is intended as an internal structure within MKVFile. If you need to create a file, you can do so through MKVFile and then use add_file.

    mkv = pymkv.MKVFile("./sample.mkv", mkvmerge_path=MKVMerge)
    mkv.add_file(pymkv.MKVFile("./sample.JPSC.ass", mkvmerge_path=MKVMerge))

[GitBib]

However, I suspect that the ensure_info decorator is not performing its intended function. I will verify this.

[GitBib]

Fixed the issue in #48 . Now, creation via a track should work without any problems.

[Masterain98]

Thank you @GitBib, I tested on my side with the latest version, and it works.

---

An off-topic question: You marked the is_bcp47 function as deprecated. What's the plan for this module? In my project, I handled some subtitle files with very specific regional codes and got errors (highfestiva/bcp47.py#7), so I'm trying make a new verification method.