It looks like you're asking for a long-form article targeting a very specific keyword phrase:
If your converted file is shorter or longer, re-check your source cropping and start/end points in your conversion tool.
To avoid confusion like convert02 , adopt a standard:
[ID]_[Language]_[SubtitleType]_[VideoCodec]_[Runtime].ext
If you meant something else by “convert” (like format change, translation, or timestamp correction), please clarify, and I’ll guide you accordingly.