Java Youtube Downloader

JavaYoutubeDownloader (JYD) is a specialized utility library designed to bridge the gap between Java applications and YouTube’s media delivery network.

It abstracts the complexity of reverse-engineering YouTube’s video player logic, allowing developers to decipher obfuscated stream signatures and extract raw video/audio containers (MP4, WebM) with a fluent, type-safe API.

Library Capabilities

:: Signature Deciphering

Implements algorithms to parse and execute YouTube’s “cipher” JavaScript logic locally, converting protected signatures into valid download URLs without a browser.

:: Multi-Strategy Decoding

Uses a robust fallback system (MultipleDecoderMethod). It attempts to extract metadata from the HTML structure, the embedded player API, and legacy endpoints to ensure high availability.

:: Stream Querying API

Leverages the Java Stream API to filter formats. Developers can easily query for specific codecs, resolutions (“1080p”), or types (“Video only”, “Audio only”) using predicates.

:: Maven Ready

Designed as a drop-in dependency. It handles the underlying HTTP networking and JSON parsing, exposing only high-level domain objects (YoutubeVideo, StreamOption).

Integration

The library is designed to be concise. Here is how you initialize the decoder and extract the highest-quality video stream available.

public void downloadVideo(String url, File outputFolder) {
    // 1. Decode the video metadata using multiple extraction strategies (AND logic)
    YoutubeVideo video = JavaYoutubeDownloader.decodeOrNull(
        url,
        MultipleDecoderMethod.AND,
        "html", "embedded"
    );

    if (video == null) throw new RuntimeException("Failed to decode video info");

    // 2. Filter streams: Get best quality with both Video & Audio
    StreamOption bestOption = video.getStreamOptions().stream()
        .filter(opt -> opt.getType().hasVideo() && opt.getType().hasAudio())
        .max(Comparator.comparingInt(opt -> opt.getType().getVideoQuality().ordinal()))
        .orElseThrow();

    System.out.println("Downloading: " + bestOption.getType());

    // 3. Output file management
    String filename = video.getTitle() + "." + bestOption.getType().getContainer();
    File targetFile = new File(outputFolder, filename);

    // 4. Start async download
    StreamDownloader downloader = new StreamDownloader(bestOption, targetFile, null);
    new Thread(downloader).start();
}

Technical Context

YouTube links are not static. The platform serves content via dynamic URLs protected by a rolling signature algorithm that changes frequently.

JYD works by fetching the video page, extracting the player JavaScript bundle, identifying the deciphering functions via Regex/Parsing, and executing that logic in Java to sign the request. This allows for automation pipelines, archival tools, or custom media players to access the raw content stream.