miru/app/js/subtitleOctopus.js

const { SubtitleStream } = MatroskaSubtitles
const { SubtitleParser } = MatroskaSubtitles

function subStream(stream) { // subtitle parsing with seeking support
    if (playerData.subtitleStream) {
        playerData.subtitleStream = new SubtitleStream(playerData.subtitleStream)
    } else {
        playerData.subtitleStream = new SubtitleStream()
        playerData.subtitleStream.once('tracks', pTracks => {
            bcap.removeAttribute("disabled")
            playerData.headers = []
            pTracks.forEach(track => {
                if (track.type != "ass") { // overwrite webvtt header with custom one
                    track.header = `[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,${Object.values(subtitle1list.options).filter(item => item.value == settings.subtitle1)[0].innerText}
[Events]

`
                }
                playerData.headers[track.number] = track
                playerData.subtitles[track.number] = new Set()
                if (!playerData.selectedHeader) playerData.selectedHeader = track.number
            })
        })
    }
    playerData.subtitleStream.on('subtitle', (subtitle, trackNumber) => {
        if (playerData.headers && !playerData.parsed) {
            if (playerData.headers[trackNumber].type == "webvtt") convertSub(subtitle)
            let formatSub = "Dialogue: " + (subtitle.layer || 0) + "," + new Date(subtitle.time).toISOString().slice(12, -1).slice(0, -1) + "," + new Date(subtitle.time + subtitle.duration).toISOString().slice(12, -1).slice(0, -1) + "," + (subtitle.style || "Default") + "," + (subtitle.name || "") + "," + (subtitle.marginL || "0") + "," + (subtitle.marginR || "0") + "," + (subtitle.marginV || "0") + "," + (subtitle.effect || "") + "," + subtitle.text
            playerData.subtitles[trackNumber].add(formatSub)
            if (playerData.selectedHeader == trackNumber) renderSubs(trackNumber)
        }
    })
    playerData.subtitleStream.on('file', file => {
        if (file.mimetype == ("application/x-truetype-font" || "application/font-woff")) playerData.fonts.push(window.URL.createObjectURL(new Blob([file.data], { type: file.mimetype })))
    })
    stream.pipe(playerData.subtitleStream)
}
let octopusTimeout
async function renderSubs(trackNumber) {
    if (!playerData.octopusInstance) {
        let options = {
            video: video,
            targetFps: await playerData.fps,
            subContent: trackNumber ? playerData.headers[trackNumber].header.slice(0, -1) + Array.from(playerData.subtitles[trackNumber]).join("\n") : playerData.headers[3].header.slice(0, -1),
            lossyRender: true,
            fonts: playerData.fonts?.length != 0 ? playerData.fonts : ["https://fonts.gstatic.com/s/roboto/v20/KFOlCnqEu92Fr1MmEU9fBBc4.woff2"],
            workerUrl: 'js/subtitles-octopus-worker.js',
            timeOffset: 0
        };
        if (!playerData.octopusInstance) playerData.octopusInstance = new SubtitlesOctopus(options);
    } else {
        if (!octopusTimeout) {
            octopusTimeout = setTimeout(() => {
                octopusTimeout = undefined
                if (playerData.octopusInstance) playerData.octopusInstance.setTrack(trackNumber ? playerData.headers[trackNumber].header.slice(0, -1) + Array.from(playerData.subtitles[trackNumber]).join("\n") : playerData.headers[3].header.slice(0, -1))
            }, 1000)
        }
    }
}
function convertSub(subtitle) { // converts vtt subtitles to ssa ones
    let matches = subtitle.text.match(/<[^>]+>/g); // create array of all tags
    if (matches)
        matches.forEach(match => {
            if (/<\//.test(match)) { // check if its a closing tag
                subtitle.text = subtitle.text.replace(match, match.replace("</", "{\\").replace(">", "0}"))
            } else {
                subtitle.text = subtitle.text.replace(match, match.replace("<", "{\\").replace(">", "1}"))
            }
        })
    //replace all html special tags with normal ones
    subtitle.text.replace(/&amp;/g, "&").replace(/&lt;/g, "<").replace(/&gt;/g, ">").replace(/&nbsp;/g, "\\h")
}
function postDownload(file) { // parse subtitles fully after a download is finished
    return new Promise((resolve, reject) => {
        if (file.name.endsWith(".mkv") || file.name.endsWith(".webm")) {
            let parser = new SubtitleParser()
            parser.once('tracks', pTracks => {
                pTracks.forEach(track => {
                    if (track.type != "ass") { // overwrite webvtt header with custom one
                        track.header = `[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,${Object.values(subtitle1list.options).filter(item => item.value == settings.subtitle1)[0].innerText}
[Events]

`
                    }
                    playerData.headers[track.number] = track
                    if (!playerData.subtitles[track.number]) playerData.subtitles[track.number] = new Set()
                })
            })
            parser.on('subtitle', (subtitle, trackNumber) => {
                if (playerData.headers[trackNumber].type == "webvtt") convertSub(subtitle)
                playerData.subtitles[trackNumber].add("Dialogue: " + (subtitle.layer || 0) + "," + new Date(subtitle.time).toISOString().slice(12, -1).slice(0, -1) + "," + new Date(subtitle.time + subtitle.duration).toISOString().slice(12, -1).slice(0, -1) + "," + (subtitle.style || "Default") + "," + (subtitle.name || "") + "," + (subtitle.marginL || "0") + "," + (subtitle.marginR || "0") + "," + (subtitle.marginV || "0") + "," + (subtitle.effect || "") + "," + subtitle.text)
            })
            parser.on('finish', () => {
                console.log("Sub parsing finished")
                playerData.parsed = 1
                playerData.subtitleStream = undefined
                renderSubs(playerData.selectedHeader)
                parser = undefined
                if (!video.paused) {
                    video.pause();
                    playVideo();
                }
                resolve();
            });
            console.log("Sub parsing started")
            file.createReadStream().pipe(parser)
        }
    })
}