CaptionConverter: turning any subtitle file into scrolling lyrics

Music players show scrolling lyrics from .lrc files — timestamped text like [01:23.45]lyric line. Subtitles come in a dozen other formats. This project, SrtToLrcConverterSimple-CSharp, converts between them, available as both a WPF desktop app and a command-line tool sharing one conversion core.

Eight input formats, auto-detected by content

SRT, WebVTT, SSA/ASS, SAMI, MicroDVD (frame-based, configurable FPS), MPL2, PJS and TTML/DFXP (XML). The interesting decision: detection is by content, not file extension. Extensions lie — a ".srt" may actually be VTT. Each format has a recognisable signature (SRT's numeric counters, WebVTT's WEBVTT header, TTML's XML namespace), and the converter sniffs before parsing. Batch mode walks a folder recursively, and one bad file is reported and skipped instead of aborting the run.

The parsing lessons in here are transferable

• Timestamps are harder than they look. 00:01:02,500 (SRT) vs 00:01:02.500 (VTT) vs deciseconds (MPL2) vs frames-at-FPS (MicroDVD) — a converter must normalise all of them to milliseconds before anything else.
• Encoding matters. Files arrive as UTF-8, UTF-16 with BOM, or legacy ANSI; the tool auto-detects (BOM first, then UTF-8 validity, then ANSI fallback) and lets you pin an explicit encoding.
• Markup stripping is a pipeline. <i>Hello</i> and ASS {\i1} overrides both become plain Hello.

Project structure

One solution, two UIs, one core library. The WPF app adds drag-and-drop and progress; the CLI adds automation. Conversion logic lives in neither — it is the shared dependency, which is why both stay correct.

Repository: github.com/bobhuang1/SrtToLrcConverterSimple-CSharp