Struct VttFormat 

pub struct VttFormat;

Subtitle format implementation for WebVTT.

The VttFormat struct implements parsing, serialization, and detection for WebVTT files. See the parser module documentation for the malformed-input disposition matrix observed by VttFormat::parse.

Trait Implementations

impl SubtitleFormat for VttFormat

fn parse(&self, content: &str) -> Result<Subtitle>

Parse WebVTT content.

Malformed-input dispositions

• Empty input → returns crate::error::SubXError::SubtitleFormat.
• Missing WEBVTT signature → returns crate::error::SubXError::SubtitleFormat.
• Leading UTF-8 BOM with valid content → BOM is consumed and the file is parsed normally. This parser-level strip is additive to crate::core::formats::encoding::converter’s file-layer strip; both layers coexist by design.
• Leading UTF-8 BOM with otherwise invalid content → returns crate::error::SubXError::SubtitleFormat (the post-BOM WEBVTT check fails).
• Out-of-order cues → preserved in original file order; no implicit sort is performed.
• Cue marker line with a negative timestamp → that block is skipped, a debug! log records the skip, and parsing continues.
• Cue body exceeding the per-cue cap (1 MiB) → returns crate::error::SubXError::SubtitleFormat. The cap is enforced on raw pre-normalization bytes, so \r\n padding cannot bypass the limit by shrinking under line-ending normalization.
• CRLF (\r\n), bare-CR (\r), or mixed line endings → input is normalized to LF after the WEBVTT header check and before block splitting; CRLF and mixed inputs parse to the same entry count and text content as their LF counterpart.
• Final cue not followed by a trailing blank line → still recognized; the file parses successfully.

fn serialize(&self, subtitle: &Subtitle) -> Result<String>

Serialize a Subtitle structure into format-specific text representation.

fn detect(&self, content: &str) -> bool

Detect whether the provided content matches this subtitle format.

fn format_name(&self) -> &'static str

Returns the human-readable name of this subtitle format.

fn file_extensions(&self) -> &'static [&'static str]

Returns the list of supported file extensions for this format.

fn supports_styling(&self) -> bool

Check if this format supports advanced styling features.

fn uses_frame_timing(&self) -> bool

Check if this format uses frame-based timing.