api/stream: split types.js into proxy.js and ffmpeg.js

api/src/stream/ffmpeg.js

@@ -0,0 +1,212 @@
+import ffmpeg from "ffmpeg-static";
+import { spawn } from "child_process";
+import { create as contentDisposition } from "content-disposition-header";
+
+import { env } from "../config.js";
+import { destroyInternalStream } from "./manage.js";
+import { hlsExceptions } from "../processing/service-config.js";
+import { closeResponse, pipe, estimateTunnelLength, estimateAudioMultiplier } from "./shared.js";
+
+const metadataTags = [
+    "album",
+    "composer",
+    "genre",
+    "copyright",
+    "title",
+    "artist",
+    "album_artist",
+    "track",
+    "date",
+    "sublanguage"
+];
+
+const convertMetadataToFFmpeg = (metadata) => {
+    const args = [];
+
+    for (const [ name, value ] of Object.entries(metadata)) {
+        if (metadataTags.includes(name)) {
+            if (name === "sublanguage") {
+                args.push('-metadata:s:s:0', `language=${value}`);
+                continue;
+            }
+            args.push('-metadata', `${name}=${value.replace(/[\u0000-\u0009]/g, "")}`); // skipcq: JS-0004
+        } else {
+            throw `${name} metadata tag is not supported.`;
+        }
+    }
+
+    return args;
+}
+
+const killProcess = (p) => {
+    p?.kill('SIGTERM'); // ask the process to terminate itself gracefully
+
+    setTimeout(() => {
+        if (p?.exitCode === null)
+            p?.kill('SIGKILL'); // brutally murder the process if it didn't quit
+    }, 5000);
+}
+
+const getCommand = (args) => {
+    if (typeof env.processingPriority === 'number' && !isNaN(env.processingPriority)) {
+        return ['nice', ['-n', env.processingPriority.toString(), ffmpeg, ...args]]
+    }
+    return [ffmpeg, args]
+}
+
+const render = async (res, streamInfo, ffargs, multiplier) => {
+    let process;
+    const urls = Array.isArray(streamInfo.urls) ? streamInfo.urls : [streamInfo.urls];
+    const shutdown = () => (
+        killProcess(process),
+        closeResponse(res),
+        urls.map(destroyInternalStream)
+    );
+
+    try {
+        // if the streamInfo.urls is an array but doesn't have 2 urls,
+        // then something went wrong
+        if (Array.isArray(streamInfo.urls) && streamInfo.urls.length !== 2) {
+            return shutdown();
+        }
+
+        const args = [
+            '-loglevel', '-8',
+            ...ffargs,
+        ];
+
+        process = spawn(...getCommand(args), {
+            windowsHide: true,
+            stdio: [
+                'inherit', 'inherit', 'inherit',
+                'pipe'
+            ],
+        });
+
+        const [,,, muxOutput] = process.stdio;
+
+        res.setHeader('Connection', 'keep-alive');
+        res.setHeader('Content-Disposition', contentDisposition(streamInfo.filename));
+        res.setHeader('Estimated-Content-Length', await estimateTunnelLength(streamInfo, multiplier));
+
+        pipe(muxOutput, res, shutdown);
+
+        process.on('close', shutdown);
+        res.on('finish', shutdown);
+    } catch {
+        shutdown();
+    }
+}
+
+const remux = async (streamInfo, res) => {
+    const format = streamInfo.filename.split('.').pop();
+    const urls = Array.isArray(streamInfo.urls) ? streamInfo.urls : [streamInfo.urls];
+    const args = [...urls.flatMap(url => ['-i', url])];
+
+    if (streamInfo.subtitles) {
+        args.push(
+            '-i', streamInfo.subtitles,
+            '-map', `${urls.length}:s`,
+            '-c:s', format === 'mp4' ? 'mov_text' : 'webvtt',
+        );
+    }
+
+    if (urls.length === 2) {
+        args.push(
+            '-map', '0:v',
+            '-map', '1:a',
+            '-c:v', 'copy',
+            '-c:a', 'copy'
+        );
+    } else {
+        args.push('-c:v', 'copy');
+
+        if (streamInfo.type === 'mute') {
+            args.push('-an');
+        } else {
+            args.push('-c:a', 'copy');
+        }
+    }
+
+    if (format === 'mp4') {
+        args.push('-movflags', 'faststart+frag_keyframe+empty_moov');
+    }
+
+    if (streamInfo.type !== 'mute' && streamInfo.isHLS && hlsExceptions.includes(streamInfo.service)) {
+        if (streamInfo.service === 'youtube' && format === 'webm') {
+            args.push('-c:a', 'libopus');
+        } else {
+            args.push('-c:a', 'aac', '-bsf:a', 'aac_adtstoasc');
+        }
+    }
+
+    if (streamInfo.metadata) {
+        args.push(...convertMetadataToFFmpeg(streamInfo.metadata));
+    }
+
+    args.push('-f', format === 'mkv' ? 'matroska' : format, 'pipe:3');
+
+    await render(res, streamInfo, args);
+}
+
+const convertAudio = async (streamInfo, res) => {
+    const args = [
+        '-i', streamInfo.urls,
+        '-vn',
+        ...(streamInfo.audioCopy ? ['-c:a', 'copy'] : ['-b:a', `${streamInfo.audioBitrate}k`]),
+    ];
+
+    if (streamInfo.audioFormat === 'mp3' && streamInfo.audioBitrate === '8') {
+        args.push('-ar', '12000');
+    }
+
+    if (streamInfo.audioFormat === 'opus') {
+        args.push('-vbr', 'off');
+    }
+
+    if (streamInfo.audioFormat === 'mp4a') {
+        args.push('-movflags', 'frag_keyframe+empty_moov');
+    }
+
+    if (streamInfo.metadata) {
+        args.push(...convertMetadataToFFmpeg(streamInfo.metadata));
+    }
+
+    args.push(
+        '-f',
+        streamInfo.audioFormat === 'm4a' ? 'ipod' : streamInfo.audioFormat,
+        'pipe:3'
+    );
+
+    await render(
+        res,
+        streamInfo,
+        args,
+        estimateAudioMultiplier(streamInfo) * 1.1,
+    );
+}
+
+const convertGif = async (streamInfo, res) => {
+    const args = [
+        '-i', streamInfo.urls,
+
+        '-vf',
+        'scale=-1:-1:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse',
+        '-loop', '0',
+
+        '-f', "gif", 'pipe:3',
+    ];
+
+    await render(
+        res,
+        streamInfo,
+        args,
+        60,
+    );
+}
+
+export default {
+    remux,
+    convertAudio,
+    convertGif,
+}