Fix neg_threshold

[Purfview]

Fix neg_threshold.
Now it should work properly, before its default was hardcoded to 0.35

[MahmoudAshraf97]

the default was 0.35 indeed but it's not hardcoded and can changed when initializing VadOptions
a simpler solution would be

    threshold: float = 0.5
-    neg_threshold: float = threshold - 0.15
+    neg_threshold: float = max(threshold - 0.15, 0)
    min_speech_duration_ms: int = 0
    max_speech_duration_s: float = float("inf")
    min_silence_duration_ms: int = 2000
    speech_pad_ms: int = 400

this would remove the need for other changes as it will not be None and if it's set explicitly to a negative it will behave as zero, so no need to handle this

edit: and since there is no issue if it is a negative value, then even the solution above is not needed, it will be merely cosmetic

[Purfview]

but it's not hardcoded

vad_parameters = {}
vad_parameters['threshold'] = 0.2

model.transcribe(fileaudio, vad_filter=True, vad_parameters=vad_parameters)

# prints below this line https://github.com/SYSTRAN/faster-whisper/blob/f32c0e8af3f2843bf70071d3d14a480a6a23da66/faster_whisper/vad.py#L93
# vad.py_print threshold: 0.2
# vad.py_print neg_threshold: 0.35   <- hardcoded, should be 0.05

since there is no issue if it is a negative value, then even the solution above is not needed, it will be merely cosmetic

Yeah, I didn't looked if there is an issue, just that it's that way in the original silero [it's not zero] -> repo

[abedkhooli]

I can't set the threshold itself in v 1.1.0 (and can't read it from vad.VadOptions).

[Purfview]

I can't set the threshold itself in v 1.1.0 (and can't read it from vad.VadOptions).

Look there: #1181