VAD Fix: explicit safe context, reduced RAM usage

[Purfview]

VAD Fix: explicit safe context (no view mutation).
Reduced SileroVADModel RAM usage by 9% [on 4h audio].

PR doesn't affect VAD speed nor probs output in current FW VAD functionality.
Fixes inconsistent outputs with multiple model calls [such functionality is currently not implemented].

[MahmoudAshraf97]

Hi, I get that this may modify the array in place, but I don't understand how that affects multiple model calls, do you mean consecutive calls on the same audio array or multiple calls in parallel for the same or different audios?

[Purfview]

do you mean consecutive calls on the same audio array or multiple calls in parallel for the same or different audios?

As I remember it affected both consecutive and parallel calls with different size audios.

Not sure now, I think it affected same size audios too but only(?) the last prob was affected.

[Purfview]

Analyzed probs from batched VAD [with 100% overlap] vs non-batched

Pre patch stats:

Total probs             : 224965
Total diff probs        : 112396
Above > 0.00001 diffs   : 641
Above > 0.0001 diffs    : 210
Above > 0.001 diffs     : 54
Above > 0.01 diffs      : 0

After the patch:

Total probs             : 224965
Total diff probs        : 97207
Above > 0.00001 diffs   : 0
Above > 0.0001 diffs    : 0
Above > 0.001 diffs     : 0
Above > 0.01 diffs      : 0 

Off-topic:
I'm leaning towards small hardcoded overlap, need to do more analysis, then I'll make a PR for batched VAD.