/** Transcript formatting: SRT, VTT, Markdown, plain. */
export interface TranscriptSegment {
text: string;
start?: number;
end?: number;
duration?: number;
}
function formatSRT(seconds: number): string {
const hrs = Math.floor(seconds / 3600);
const mins = Math.floor((seconds % 3600) / 60);
const secs = Math.floor(seconds % 60);
const ms = Math.floor((seconds % 1) * 1000);
return `${hrs.toString().padStart(2, '0')}:${mins.toString().padStart(2, '0')}:${secs.toString().padStart(2, '0')},${ms.toString().padStart(3, '0')}`;
}
function formatVTT(seconds: number): string {
const hrs = Math.floor(seconds / 3600);
const mins = Math.floor((seconds % 3600) / 60);
const secs = Math.floor(seconds % 60);
const ms = Math.floor((seconds % 1) * 1000);
return `${hrs.toString().padStart(2, '0')}:${mins.toString().padStart(2, '0')}:${secs.toString().padStart(2, '0')}.${ms.toString().padStart(3, '0')}`;
}
function formatTime(ms: number): string {
const totalSeconds = Math.floor(ms / 1000);
const mins = Math.floor(totalSeconds / 60);
const secs = totalSeconds % 60;
return `${mins}:${secs.toString().padStart(2, '0')}`;
}
export interface ExportOptions {
videoId: string;
videoTitle?: string | null;
segments: TranscriptSegment[];
plainText?: string;
}
export type ExportFormat = 'markdown' | 'srt' | 'vtt' | 'plain';
export function exportTranscript(
options: ExportOptions,
format: ExportFormat
): string {
const { videoId, videoTitle, segments, plainText } = options;
switch (format) {
case 'plain':
return plainText ?? segments.map((s) => s.text).join('\n\n');
case 'srt':
return segments
.map((seg, i) => {
const startSec = (seg.start ?? 0) / 1000;
const endSec = (seg.end ?? seg.start ?? 0) / 1000;
return `${i + 1}\n${formatSRT(startSec)} --> ${formatSRT(endSec)}\n${seg.text}`;
})
.join('\n\n');
case 'vtt':
return (
'WEBVTT\n\n' +
segments
.map((seg) => {
const startSec = (seg.start ?? 0) / 1000;
const endSec = (seg.end ?? seg.start ?? 0) / 1000;
return `${formatVTT(startSec)} --> ${formatVTT(endSec)}\n${seg.text}`;
})
.join('\n\n')
);
case 'markdown': {
const title = videoTitle || `Transcript for ${videoId}`;
const duration =
segments.length > 0 && segments[segments.length - 1]?.end
? Math.floor((segments[segments.length - 1].end ?? 0) / 1000)
: 0;
const words = (plainText ?? segments.map((s) => s.text).join(' '))
.split(/\s+/)
.filter(Boolean).length;
return (
`# ${title}\n\n` +
`**Video ID:** ${videoId}\n` +
`**Duration:** ${Math.floor(duration / 60)}:${(duration % 60).toString().padStart(2, '0')}\n` +
`**Words:** ${words.toLocaleString()}\n\n` +
`## Transcript\n\n` +
segments
.map((seg) => `**[${formatTime(seg.start ?? 0)}]** ${seg.text}`)
.join('\n\n')
);
}
default:
throw new Error(`Unsupported format: ${format}`);
}
}
