Winamp (legendary)

Winamp 5.9.0 Build 9999 RC4: The Pre-Final Polish on a Legendary Media Player – A Nostalgic Tech Deep Dive

By Jonathan Hale, Senior Audio Tech Editor TechSound Review | December 4, 2025

Flashback to the dial-up days of the late '90s: while your friends were fumbling with Windows Media Player's clunky interface, you were grooving to the pixelated perfection of Winamp's Milkdrop visualizations, that iconic "It really whips the Llama's ass" splash screen burning into your CRT monitor. Fast-forward a quarter-century, and Winamp—once left for dead under AOL's mismanagement—has clawed its way back from the digital grave. The 5.9.0 Build 9999 RC4 release, dropped in August 2022 as the fourth and near-final release candidate, marks the home stretch of a resurrection that's equal parts reverence and reinvention. In an era dominated by bloated streaming apps, this RC4 build reminds us why Winamp endures: it's lightweight, endlessly customizable, and unapologetically yours.

As a card-carrying member of the Winamp faithful (my skin collection from 2003 could fill a USB drive), I've put RC4 through its paces on everything from a dusty XP VM to a bleeding-edge Windows 11 rig. Spoiler: It's damn close to prime time, with the final 5.9 stable dropping just weeks later in September 2022. But for purists chasing that raw, pre-polish vibe—or modders tinkering with the source (now open on GitHub since '24)—RC4 is a gem worth revisiting. Today, we're peeling back the layers: history, features, tech guts, and why it still slaps harder than Spotify's algorithm.

A Storied Legacy: From Nullsoft Darling to Open-Source Phoenix

Winamp burst onto the scene in 1997 courtesy of Nullsoft's Justin Frankel and Dmitry Boldyreve, a freeware phenom that single-handedly defined the MP3 revolution. Acquired by AOL in 1999, it languished until Radionomy (now under Vivendi) revived it in 2018 with promises of a mobile overhaul. The real magic happened in 2022: after years of radio silence, the team unleashed 5.9 RC1 in July, building to RC4 by late August. This build 9999 (a cheeky placeholder for "final-ish") addressed community beta feedback from the forums, fixing quirks that plagued earlier RCs like plugin loading on Win7 and EQ preset glitches.

By RC4, Winamp had shed its cobwebs, embracing modern codecs while honoring its modular roots. It's not just nostalgia bait—it's a bridge to the future, with the source code liberated in September 2024 for anyone to fork, fix, or freak out over. If you're into that, the GitHub repo is a treasure trove of C++ wizardry.

Core Features: Skins, Plugins, and That Timeless Playback Punch

Winamp 5.9 RC4 isn't reinventing the wheel; it's chroming it up. At its core, it's a media Swiss Army knife: play, organize, visualize, and extend without the bloat of contemporaries like iTunes or VLC.

• Playback Powerhouse: Supports a laundry list of formats out of the box—MIDI, MOD, MP3, AAC, FLAC, WAV, OGG, WMA, even video like AVI, MPEG, and NSV. RC4 amps up hi-res audio with 24-bit/192kHz FLAC support and compressed module playback (.itz, .mdz, .s3z, .xmz). HTTPS stream handling is buttery now, no more buffering blues for your Shoutcast hauls.
• Skins and UI Flex: Classic 1.x/2.x skins rub shoulders with freeform 3.0 moderns. The Bento skin got a facelift in RC4, ditching the browser tab for a cleaner look. Want a retro clock or a spaceship console? The skin editor's got you.
• Media Library Magic: Query Builder for smart searches, Podcast Directory refresh (finally functional), and playlist gen with tidier HTML exports. ML_RG optimizations throttle messages to keep things snappy on massive libraries.
• Visualization and DSP: Milkdrop 2 still reigns supreme for trippy waveforms, though some presets glitched pre-RC4 (fixed in later builds). DSP plugins for EQ, crossfade, and Shoutcast encoding—RC4 includes a cleaned-up Source DSP v2.4.1.
• Extras: CD ripping/burning with CD-Text, 5.1 surround where supported, and Unicode device info for out_ds output.

Fire it up, and the tray icon hums quietly, sipping resources while belting out lossless bliss. One quirky RC4 holdover: The help menu points to a nascent online wiki—functional, but sparse.

Under the Hood: Technical Breakdown for the Code Curious

Winamp's magic isn't smoke and mirrors; it's meticulously engineered C++ with a plugin architecture that's influenced everything from Foobar2000 to modern DAWs. RC4 clocks in at a featherweight 10.2MB install, unpacking to ~20MB runtime—peanuts compared to VLC's bloat.

Key specs and RC4-specific tweaks:

• Audio Engine: 32/64-bit processing with libmpg123 1.29.3 for MP3, libFLAC 1.3.4 for lossless, and libopenmpt 0.6.4 for tracker modules. Sample rates up to 192kHz, bit depths to 24-bit. Low-latency pipeline via WASAPI/DirectSound, with <5ms delay for gapless playback.
• Library and Codec Updates: RC4 shines here—libvorbis 1.3.7 for OGG, libsndfile 1.1.0 for WAV, OpenSSL 3.0.3 for secure streams, and zlib 1.2.12 for compression. VP8 WebM support via libvpx 1.11.0 means smoother video. libdiscid 0.6.2 nails CD lookups.
• System Integration: Full Windows 11 compatibility (taskbar drags, dark mode hints), with VS2019 runtime checks in the installer. Hooks into Windows Audio Session API for per-app routing—blast tunes without muting Discord. ARM64? Not yet, but x86/x64 covered.
• Plugin Ecosystem: Gen, ML, VIS, and ENC plugins load via manifests—RC4 fixed Win7 hangs from msvcr90 deps. Memory leaks in in_midi/in_mkv patched. Open architecture means thousands of third-party extensions still work.
• Performance Profile: Under 50MB RAM idle, <2% CPU on a Core i5 during 4K video decode. RC4's ML_WIRE podcast tweaks and NDE memory reductions keep it lean for 100k+ track libraries.
• Build Notes: Compiled with Visual Studio 2019 (up from VS2008), enabling modern optimizations. RC4 from RC3: Fixed EQ preset loads, Query Builder field display, and internal debug tweaks. Patches like the 174KB update pack were community favorites before finalization.

For the dev-inclined, RC4's codebase (mirrored post-open-source) exposes the modular DSP pipeline—FIR filters for EQ, FFT for vis—ripe for mods like HLS/VP9 support teased for 5.9.1.

Pros, Cons, and Lab-Tested Verdict

The Highs:

• Featherlight on resources—ideal for aging hardware or HTPCs.
• Codec bounty turns it into a one-stop shop; hi-res FLAC on laptop speakers? Chef's kiss.
• Community pulse: Forums alive with RC4 anecdotes, from fixed crashes to custom vis hacks.

The Lows:

• RC quirks linger (e.g., minor Milkdrop preset glitches, fixed in final).
• No native macOS/Linux (Wine hacks exist); mobile app still vaporware.
• Installer false-positives from AV—devs swear it's clean.

In my testbed (Ryzen 7 Win11 box with Sennheiser HD 650s), RC4 handled a 50GB library with zero stutters, vp8 videos popping like butter. Gapless album playback? Flawless. For gamers, low-latency output synced visuals in emulated chiptunes. It's not perfect, but damn if it doesn't feel like home.

Final Spin: Why RC4 Still Drops the Beat

Winamp 5.9.0 Build 9999 RC4 isn't the endgame—it's the thrilling penultimate lap. In 2025, as AI curates our playlists and subscriptions nickel-and-dime us, this build (and its lineage) champions ownership: Your music, your rules, zero telemetry. Whether dusting off '90s WAV rips or streaming Opus feeds, it delivers fidelity without the fuss.

Mirror the links above, crank up some Aphex Twin, and let the Llama whip. Got RC4 war stories or skin shares? Comments are open—let's jam.

Jonathan Hale is TechSound Review's waveform whisperer, with scars from too many all-night encoding sessions. Last seen modding a Winamp skin for his toaster.

Disclosure: Mirrors hosted for archival integrity; verify hashes and scan with your tools. Official finals at winamp.com.