🐞 ChannelID.Parameters["fx.start"] not always a LogNormal

[chr15m]

Describe the issue

$ python
Python 3.7.9 (default, Feb 28 2023, 14:53:52) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pyflp
>>> project = pyflp.parse("2step1.flp")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/pyflp/__init__.py", line 168, in parse
    events.append(event_type(id, value))
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/pyflp/_events.py", line 438, in __init__
    self._struct = self.STRUCT.parse(data, len=len(self._data))
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/construct/core.py", line 288, in parse
    return self.parse_stream(io.BytesIO(data), **contextkw)
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/construct/core.py", line 300, in parse_stream
    return self._parsereport(stream, context, "(parsing)")
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/construct/core.py", line 312, in _parsereport
    obj = self._parse(stream, context, path)
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/construct/core.py", line 2120, in _parse
    subobj = sc._parsereport(stream, context, path)
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/construct/core.py", line 312, in _parsereport
    obj = self._parse(stream, context, path)
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/construct/core.py", line 2653, in _parse
    return self.subcon._parsereport(stream, context, path)
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/construct/core.py", line 312, in _parsereport
    obj = self._parse(stream, context, path)
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/construct/core.py", line 3739, in _parse
    obj = sc._parsereport(stream, context, path)
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/construct/core.py", line 312, in _parsereport
    obj = self._parse(stream, context, path)
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/construct/core.py", line 704, in _parse
    return self._decode(obj, context, path)
  File "/home/chrism/dev/fakeboy.mapp/.direnv/python-3.7.9/lib/python3.7/site-packages/pyflp/_descriptors.py", line 329, in _decode
    raise ValueError(f"Not a LogNormal, 2nd int must be 63; not {obj[1]}")
ValueError: Not a LogNormal, 2nd int must be 63; not 0

Here is the file I tried to load:
2step1.flp.zip

Thank you!

What version of PyFLP are you using?

2.1.0

Code of Conduct

• I agree to follow this project's Code of Conduct

[demberto]

It seems ChannelID.Parameters["fx.start"] used an int instead of the (now) LogNormal / float representation.
While a fix for this is simple, it will be a downgrade for projects and presets saved with newer versions of FL Studio.

I need to find a better solution to such issues.

In the meantime, you can fix this by changing this line

PyFLP/pyflp/channel.py

Line 303 in a74fad0

"fx.start" / c.Optional(LogNormal(c.Int16ul[2], (0, 61440))), # 137

to

"fx.start" / c.Optional(c.Int32ul),  # 137

If you are familiar with git and Python, I recommend that you fork PyFLP, clone it locally, make the edits and install it in your environment, instead of changing this manually in your existing installation.

[chr15m]

Thank you, will try it.

[chr15m]

Could you wrap it in a try and catch the ValueError and then run the second one?

[demberto]

Could you wrap it in a try and catch the ValueError and then run the second one?

Nah it won't work that way. Its not the correct place to do it.

[chr15m]

I found a truly hacky solution for this, but maybe it can inspire something on your end. The following code monkey-patches a new version of STRUCT with the one commented out field changed.

try:
    project = pyflp.parse(flpfile)
except ValueError:
    flp_monkeypatch_pyflp()
    project = pyflp.parse(flpfile)

def flp_monkeypatch_pyflp():
    from pyflp.channel import StdEnum, _DelayFlags, ArpDirection, DeclickMode, List2Tuple, LinearMusical, StretchMode, Log2, LogNormal
    pyflp.channel.ParametersEvent.STRUCT = c.Struct(
        "_u1" / c.Optional(c.Bytes(9)),  # 9
        "fx.remove_dc" / c.Optional(c.Flag),  # 10
        "delay.flags" / c.Optional(StdEnum[_DelayFlags](c.Int8ul)),  # 11
        "keyboard.main_pitch" / c.Optional(c.Flag),  # 12
        "_u2" / c.Optional(c.Bytes(28)),  # 40
        "arp.direction" / c.Optional(StdEnum[ArpDirection](c.Int32ul)),  # 44
        "arp.range" / c.Optional(c.Int32ul),  # 48
        "arp.chord" / c.Optional(c.Int32ul),  # 52
        "arp.time" / c.Optional(c.Float32l),  # 56
        "arp.gate" / c.Optional(c.Float32l),  # 60
        "arp.slide" / c.Optional(c.Flag),  # 61
        "_u3" / c.Optional(c.Bytes(1)),  # 62
        "time.full_porta" / c.Optional(c.Flag),  # 63
        "keyboard.add_root" / c.Optional(c.Flag),  # 64
        "time.gate" / c.Optional(c.Int16ul),  # 66
        "_u4" / c.Optional(c.Bytes(2)),  # 68
        "keyboard.key_region" / c.Optional(List2Tuple(c.Int32ul[2])),  # 76
        "_u5" / c.Optional(c.Bytes(4)),  # 80
        "fx.normalize" / c.Optional(c.Flag),  # 81
        "fx.inverted" / c.Optional(c.Flag),  # 82
        "_u6" / c.Optional(c.Bytes(1)),  # 83
        "content.declick_mode" / c.Optional(StdEnum[DeclickMode](c.Int8ul)),  # 84
        "fx.crossfade" / c.Optional(c.Int32ul),  # 88
        "fx.trim" / c.Optional(c.Int32ul),  # 92
        "arp.repeat" / c.Optional(c.Int32ul),  # 96; FL 4.5.2+
        "stretching.time" / c.Optional(LinearMusical(c.Int32ul)),  # 100
        "stretching.pitch" / c.Optional(c.Int32sl),  # 104
        "stretching.multiplier" / c.Optional(Log2(c.Int32sl, 10000)),  # 108
        "stretching.mode" / c.Optional(StdEnum[StretchMode](c.Int32sl)),  # 112
        "_u7" / c.Optional(c.Bytes(21)),  # 133
        #"fx.start" / c.Optional(LogNormal(c.Int16ul[2], (0, 61440))),  # 137
        "fx.start" / c.Optional(c.Int32ul),  # 137
        "_u8" / c.Optional(c.Bytes(4)),  # 141
        "fx.length" / c.Optional(LogNormal(c.Int16ul[2], (0, 61440))),  # 145
        "_u9" / c.Optional(c.Bytes(3)),  # 148
        "playback.start_offset" / c.Optional(c.Int32ul),  # 152
        "_u10" / c.Optional(c.Bytes(5)),  # 157
        "fx.fix_trim" / c.Optional(c.Flag),  # 158 (FL 20.8.4 max)
        "_extra" / c.GreedyBytes,  # * 168 as of 20.9.1
    )