Local SoundCloud Downloader (with cover->ID3)

Download SoundCloud without external service + embed cover art into MP3 ID3 metadata.

此脚本不应直接安装。它是供其他脚本使用的外部库,要使用该库请加入元指令 // @require https://update.gf.qytechs.cn/scripts/556576/1699828/Local%20SoundCloud%20Downloader%20%28with%20cover-%3EID3%29.js

您需要先安装一个扩展,例如 篡改猴Greasemonkey暴力猴,之后才能安装此脚本。

You will need to install an extension such as Tampermonkey to install this script.

您需要先安装一个扩展,例如 篡改猴暴力猴,之后才能安装此脚本。

您需要先安装一个扩展,例如 篡改猴Userscripts ,之后才能安装此脚本。

您需要先安装一款用户脚本管理器扩展,例如 Tampermonkey,才能安装此脚本。

您需要先安装用户脚本管理器扩展后才能安装此脚本。

(我已经安装了用户脚本管理器,让我安装!)

您需要先安装一款用户样式管理器扩展,比如 Stylus,才能安装此样式。

您需要先安装一款用户样式管理器扩展,比如 Stylus,才能安装此样式。

您需要先安装一款用户样式管理器扩展,比如 Stylus,才能安装此样式。

您需要先安装一款用户样式管理器扩展后才能安装此样式。

您需要先安装一款用户样式管理器扩展后才能安装此样式。

您需要先安装一款用户样式管理器扩展后才能安装此样式。

(我已经安装了用户样式管理器,让我安装!)

// ==UserScript==
// @name         Local SoundCloud Downloader (with cover->ID3)
// @namespace    https://blog.maple3142.net/
// @version      0.2.1
// @description  Download SoundCloud without external service + embed cover art into MP3 ID3 metadata.
// @author       maple3142 + modified by ChatGPT
// @match        https://soundcloud.com/*
// @require      https://cdn.jsdelivr.net/npm/[email protected]/dist/ponyfill.min.js
// @require      https://cdn.jsdelivr.net/npm/[email protected]/StreamSaver.min.js
// @require      https://cdn.jsdelivr.net/npm/[email protected]/dist/browser-id3-writer.min.js
// @grant        none
// @license      MIT
// @icon         https://a-v2.sndcdn.com/assets/images/sc-icons/favicon-2cadd14bdb.ico
// @downloadURL  https://update.greasyfork.org/scripts/394837/Local%20SoundCloud%20Downloader.user.js
// @updateURL    https://update.greasyfork.org/scripts/394837/Local%20SoundCloud%20Downloader.meta.js
// ==/UserScript==

/* jshint esversion: 8 */

streamSaver.mitm = "https://maple3142.github.io/StreamSaver.js/mitm.html";

function hook(obj, name, callback, type) {
    const fn = obj[name];
    obj[name] = function (...args) {
        if (type === "before") callback.apply(this, args);
        fn.apply(this, args);
        if (type === "after") callback.apply(this, args);
    };
    return () => {
        // restore
        obj[name] = fn;
    };
}

function triggerDownload(url, name) {
    const a = document.createElement("a");
    document.body.appendChild(a);
    a.href = url;
    a.download = name;
    a.click();
    a.remove();
}

const btn = {
    init() {
        this.el = document.createElement("button");
        this.el.textContent = "Download";
        this.el.classList.add("sc-button");
        this.el.classList.add("sc-button-medium");
        this.el.classList.add("sc-button-icon");
        this.el.classList.add("sc-button-responsive");
        this.el.classList.add("sc-button-secondary");
        this.el.classList.add("sc-button-download");
    },
    cb() {
        const par = document.querySelector(".sc-button-toolbar .sc-button-group");
        if (par && this.el.parentElement !== par)
            par.insertAdjacentElement("beforeend", this.el);
    },
    attach() {
        this.detach();
        this.observer = new MutationObserver(this.cb.bind(this));
        this.observer.observe(document.body, { childList: true, subtree: true });
        this.cb();
    },
    detach() {
        if (this.observer) this.observer.disconnect();
    }
};

btn.init();

function getClientId() {
    return new Promise((resolve) => {
        const restore = hook(
            XMLHttpRequest.prototype,
            "open",
            function (method, url) {
                const u = new URL(url, document.baseURI);
                const clientId = u.searchParams.get("client_id");
                if (!clientId) return;
                console.log("got clientId", clientId);
                restore();
                resolve(clientId);
            },
            "after"
        );
    });
}

const clientIdPromise = getClientId();
let controller = null;

// helper: try to build best artwork url
function artworkBestUrl(track) {
    // track.artwork_url often contains e.g. -large.jpg ; try t500x500 or original; fallback to user avatar
    let art = track.artwork_url || (track.user && track.user.avatar_url) || null;
    if (
        !art &&
        track.publisher_metadata &&
        track.publisher_metadata.artwork &&
        track.publisher_metadata.artwork.url
    ) {
        art = track.publisher_metadata.artwork.url;
    }
    if (!art) return null;
    // replace size placeholders commonly used by SoundCloud
    return art.replace("-large", "-t500x500").replace("-crop", "-t500x500");
}

// fetch arrayBuffer with simple error handling
async function fetchArrayBuffer(url, signal) {
    const resp = await fetch(url, { signal });
    if (!resp.ok) throw new Error("Fetch failed: " + resp.status);
    return resp.arrayBuffer();
}

async function load(by) {
    btn.detach();
    console.log("load by", by, location.href);
    if (
        /^(\/(you|stations|discover|stream|upload|search|settings))/.test(
            location.pathname
        )
    )
        return;
    const clientId = await clientIdPromise;
    if (controller) {
        controller.abort();
        controller = null;
    }
    controller = new AbortController();
    const result = await fetch(
        `https://api-v2.soundcloud.com/resolve?url=${encodeURIComponent(
            location.href
        )}&client_id=${clientId}`,
        { signal: controller.signal }
    )
        .then((r) => r.json())
        .catch((e) => {
            console.warn("resolve failed", e);
            return {};
        });
    console.log("result", result);
    if (result.kind !== "track") return;
    btn.el.onclick = async () => {
        try {
            const progressive =
                result.media &&
                result.media.transcodings &&
                result.media.transcodings.find(
                    (t) => t.format && t.format.protocol === "progressive"
                );
            if (!progressive) {
                alert("Sorry, downloading this music is currently unsupported.");
                return;
            }
            // get the actual progressive audio URL
            const { url } = await fetch(
                progressive.url + `?client_id=${clientId}`
            ).then((r) => r.json());
            // fetch audio as ArrayBuffer (required to write ID3)
            const audioBuf = await fetchArrayBuffer(url);
            // try to fetch artwork
            let coverBuf = null;
            const artUrl = artworkBestUrl(result);
            if (artUrl) {
                try {
                    // SoundCloud sometimes returns SVG/other or redirects — let errors be caught
                    coverBuf = await fetchArrayBuffer(artUrl);
                } catch (e) {
                    console.warn("cover fetch failed", e);
                    coverBuf = null;
                }
            }

            // Use browser-id3-writer to set tags
            // ID3Writer is provided by browser-id3-writer (required at top)
            let filename = (result.title || "track") + ".mp3";
            // sanitize filename a bit
            filename = filename.replace(/[\/\\?%*:|"<>]/g, "_");

            let taggedBlob = null;
            try {
                const writer = new ID3Writer(audioBuf);
                // Basic tags
                if (result.title) writer.setFrame("TIT2", result.title);
                if (result.user && result.user.username)
                    writer.setFrame("TPE1", [result.user.username]);
                if (
                    result.publisher_metadata &&
                    result.publisher_metadata.album_title
                ) {
                    writer.setFrame("TALB", result.publisher_metadata.album_title);
                } else if (result.title) {
                    // optional: nothing
                }
                // add cover if available
                if (coverBuf) {
                    // attempt to detect mime from first bytes (jpeg/png)
                    let mime = "image/jpeg"; // default
                    const dv = new Uint8Array(coverBuf);
                    if (dv[0] === 0x89 && dv[1] === 0x50 && dv[2] === 0x4e)
                        mime = "image/png";
                    writer.setFrame("APIC", {
                        type: 3,
                        data: coverBuf,
                        description: "Cover",
                        mime: mime
                    });
                }
                writer.addTag();
                taggedBlob = writer.getBlob();
            } catch (e) {
                console.warn("ID3 tagging failed, falling back to raw file", e);
                // if tagging failed, fallback to raw audio
                taggedBlob = new Blob([audioBuf], { type: "audio/mpeg" });
            }

            // Attempt to save using StreamSaver (good for large files)
            // Note: StreamSaver supports streaming a blob stream to disk: taggedBlob.stream()
            try {
                const fileStream = streamSaver.createWriteStream(filename, {
                    size: taggedBlob.size
                });
                // Use readable stream from blob and pipe to streamSaver
                const readable = taggedBlob.stream();
                if (readable.pipeTo) {
                    await readable.pipeTo(fileStream);
                } else {
                    // fallback: manual pump
                    const reader = readable.getReader();
                    const writer = fileStream.getWriter();
                    const pump = () =>
                        reader
                            .read()
                            .then(({ done, value }) =>
                                done ? writer.close() : writer.write(value).then(pump)
                            );
                    await pump();
                }
            } catch (e) {
                // fallback to normal download via object URL
                console.warn("StreamSaver failed, fallback to anchor download", e);
                const urlObj = URL.createObjectURL(taggedBlob);
                triggerDownload(urlObj, filename);
                // release object URL after a while
                setTimeout(() => URL.revokeObjectURL(urlObj), 60 * 1000);
            }
        } catch (err) {
            console.error("Download failed", err);
            alert("Download error: " + (err.message || err));
        }
    };
    btn.attach();
    console.log("attached");
}

load("init");
hook(history, "pushState", () => load("pushState"), "after");
window.addEventListener("popstate", () => load("popstate"));