XCaster is a standalone Windows desktop app for x.com built for X Spaces streamers who need professional, isolated audio — no BlueStacks, no browser limitations, no audio leaking where it shouldn't.
It ships its own Chromium (via Electron), disables WebRTC AGC at the engine level, and injects a full DSP mixer into the app itself — turning XCaster into a global audio surface where every tab is an independent, isolated input channel.
Windows (x64) XCaster v1.4.7 — XCaster-win32-x64.zip
macOS (Apple Silicon / arm64) XCaster v1.4.7 — XCaster-darwin-arm64.zip
macOS (Intel / x64) XCaster v1.4.7 — XCaster-darwin-x64.zip
Extract the zip and run XCaster.exe (Windows) or XCaster.app (macOS) — no installer required.
macOS note: First launch requires right-click → Open to bypass Gatekeeper (app is not notarized).
- The Speakers pane could warn that incoming Space audio had stopped while the Space was working perfectly — most reliably when hosting, because a host with no other speakers legitimately receives no audio at all.
- Worse than the warning: it silently retried the connection every 20 seconds, which disturbed the Space player. Both the warning and the automatic retry are gone.
- A host's own live microphone track could be swapped out every 4 seconds if any unrelated connection looked stale — interrupting the broadcast. Only genuinely broken connections are touched now, and it gives up instead of retrying forever.
- Output-device and background-throttling settings were being re-applied every couple of seconds even when nothing had changed. They are now applied only on an actual change.
- Media elements are no longer captured before they have anything to play, which cuts a large amount of pointless work on busy pages.
- Setting
XCASTER_DEBUG_PORTenables a local debugging port so audio problems can be traced in a running app. Off by default.
- Fixed the X Space player collapsing and reopening by itself every couple of seconds.
- A background check that asks each tab whether it is carrying a live Space was registering as a user interaction with the page each time it ran. X reasonably treated that as you tapping the player, and toggled it. The check now runs without pretending to be a click.
- Introduced in v1.4.4, which widened that check from hidden tabs to every tab — so it only affected a Space you were actually watching from v1.4.4 onward. Anyone on v1.4.4 or v1.4.5 should update.
- The wallet/extension feature had no interface left, but it was still loading extension code into every page you opened, on every launch. It is gone, along with the injected script that was throwing
TransportTimeoutErrorerrors into the console. - If you had MetaMask installed through XCaster, its ~86 MB of extension code under
%APPDATA%/XCaster/extensionsis no longer used and can be deleted.
- F12 now opens the console for the X tab, which is where XCaster writes its audio diagnostics.
Ctrl+Shift+Iopens the app shell's console, a different window that never showed them — so if audio ever misbehaves, F12 is the one you want. - It opens in its own detached window, because the X tab always draws over the app and used to hide the console completely.
- Fixed Space audio degrading or dropping while you worked in another application, which is behaviour that goes back as far as v0.5.
- XCaster already told Chromium not to throttle itself in the background, and v1.4.3 stopped it throttling a Space you had switched tabs away from. Neither covers the operating system deciding that a background app deserves less CPU — and the processes it deprioritises are exactly the ones decoding the Space and mixing your audio, each of which runs separately from the app's main process and was never raised.
- Those processes are now given elevated priority while you are actually in a Space, and put back to normal when you leave, so an idle XCaster stays a well-behaved background app.
- If the connection carrying a Space dies, XCaster now notices and automatically retries it, instead of leaving you with silent audio until you leave and rejoin.
- The stall detection added in v1.4.3 had a blind spot: it only examined healthy connections, so a connection that had actually failed was skipped and reported as "not in a Space" — it went quiet in exactly the situation it was built for. A failed connection is now reported immediately and is no longer dropped from tracking, which had also caused the tab to be de-prioritised at the moment it most needed to recover.
- Recovery is automatic now rather than a button you had to find. The Recover incoming audio button remains in the Speakers pane for a second attempt.
- Fixed Space audio cutting out the moment you switched to another tab in the built-in browser, staying dead until you left and rejoined.
- Cause: hiding an X tab detached it from the window and then deliberately re-enabled Chromium background throttling on it. That is right for an idle tab — it is what stops background tabs burning CPU forever — but it made no exception for a tab carrying a live Space, and throttled timers stall the WebRTC pipeline.
- A hidden Space now keeps unthrottled timers while still doing no rendering work, so it keeps streaming without costing you the CPU saving. Idle hidden tabs are throttled exactly as before, and the policy re-checks itself every couple of seconds, so a tab that leaves a Space goes back to being throttled.
- Fixed the mixer meters sitting at zero when you first opened the gear, until you clicked Reapply audio graph.
- Two causes: opening the panel never built the audio graph, and the meters bound to their analysers only once — so a panel opened before the graph existed stayed dead, and a later rebuild left them reading replaced analysers. Meters now attach to the graph whenever it appears or is rebuilt.
- Decoded instrument samples were cached without any limit. They are stored as raw PCM, so a 1 MB compressed sample costs 10–20 MB in memory, and every instrument you opened in the GM catalog stayed resident until you reloaded the tab.
- There is now a memory budget with least-recently-used eviction, plus a full release once the Sounds rig has been idle a few minutes. Sounds already playing are unaffected; the only cost is a brief reload the next time you use an instrument that was dropped.
- The background video was also being decoded by every tab at once, even with the skin turned off. Only the tab you are looking at decodes it now, and with the skin off it is not created at all. A per-tab background worker now starts only where there is actually audio to protect.
- If incoming Space audio stops arriving, XCaster now notices instead of leaving you guessing, and the Speakers pane offers a Recover incoming audio button that retries the connection without making you leave the Space.
- Fixed incoming Space audio stopping mid-Space and staying dead until you left and rejoined. Every other channel kept working, which is why it looked like X's problem rather than the mixer's.
- Cause: the capture side (mic, Aux 1/2, the outgoing sender) has had automatic recovery for a while, but the playback side had none — the only check was "resume the output context if it is suspended". If the output device stalled, most often a USB interface re-enumerating mid-Space, the context kept reporting itself as running while no audio flowed, and nothing noticed.
- XCaster now watches the output context for a stalled render clock or a non-running state, and restores it in place — resuming it, re-applying the output device, and restarting any stalled playback element. Recovery is paced so a genuinely dead device can't thrash your output.
- If it ever does freeze again, the console now names the condition that fired.
- The built-in browser granted microphone/camera and geolocation to every site it loaded, not just x.com. Because XCaster ships a general browser (YouTube, TibetSwap, your own bookmarks), any page you opened — including a malicious link — could capture the mic or your location with no prompt.
- Both are now restricted to x.com / twitter.com. Low-risk permissions (notifications, clipboard, pointer lock, Web MIDI) stay available everywhere so the app-wide mixer and hardware MIDI controllers keep working; anything else is denied by default.
- X Spaces, the xCaster tab-capture channel and MIDI are unaffected. The one visible change: opening the gear on a non-X tab can no longer acquire the microphone — that is the hole being closed, and the X tab's mixer (the one feeding your Space) is untouched.
This is the first stable build of the Soundboard + MIDI instrument + Loop Station line — it ships everything from the v1.3.0 beta series plus a full General MIDI instrument catalog and two mixer mute fixes.
- "Mute mic" no longer silences everything. The panel toggle zeroed the mic channel gain but also disabled the WebRTC sender track — and that track carries the whole mix (Mic + Aux 1 + Aux 2 + xCaster + Sounds), so muting the mic cut the entire broadcast. It is now a channel mute only; Aux, xCaster and Sounds keep sending.
- X's own mic button inside a Space now works. XCaster hands X a clone of the processed mix and swaps in fresh clones on device changes, so the track object X held drifted away from the one actually being sent — X's mute button flipped
enabledon a stale clone and had no effect on the audio. That toggle is now intercepted and translated into a real broadcast mute: nothing reaches the Space, while your headset monitor and the broadcast-out device (virtual cable) keep running. - The Mic pane shows a live X Space mic: live / MUTED status line so you can tell which of the two mutes is engaged.
- Full GM instrument catalog via WebAudioFont, loaded through a safe parser (no
eval), with 10 instrument tabs and a per-tab instrument selector — clicking a kit tab auto-loads its instrument - Full chromatic keyboard for melodic WebAudioFont/SFZ kits, and direct SFZ region lookup replacing the old 16-pad nearest-neighbour stretch, so sampled instruments play correctly across the whole keyboard instead of one octave
- Grouped kit selector (Drums / Keys / Guitar / FX) with real sampled Acoustic (FreePats muldjordkit, CC-BY) and Electric Guitar Clean (FreePats FSBS, CC0) kits
- Proper DAW-style 1-2-3-4 count-in on first record, skipped automatically when quantize is off
- Piano roll opens from the Loop Station — resizable on both axes, with a quantize button
- Metronome click track, and the pad grid now reads bottom-to-top like a hardware controller
- Wider panel with wrapping tabs
Released as a beta series (v1.3.0-beta.1 … .3); these features first shipped in a stable build as part of v1.4.0 above.
This release adds a full Soundboard + MIDI instrument + Loop Station rig to the mixer, on top of X Spaces reliability fixes.
- Full Web MIDI support — pick your input device and channel in the new Sounds → MIDI pane, with a live raw-message monitor so you can confirm hardware is being seen even before anything is mapped
- Learn mode for mapping any pad, and for mapping a hardware Record/Play transport button (e.g. Launchkey-style controllers), with unlearn buttons and auto-cancel so a bad mapping can't get stuck
- Built-in synth layer — "Enable synth" routes MIDI notes to an oscillator + filter voice (waveform, attack/decay/sustain/release, filter cutoff/resonance, octave shift, velocity sensitivity) that plays on top of whatever pad is mapped to that key, not instead of it
- Fixed piano/guitar/synth-keys pads being silent outside their fixed 16-key range (e.g. using a controller's Octave +/- button) — melodic kits now pitch-shift across the full keyboard instead of only responding to one octave
- Fixed a mis-learn race where a stray pad hit while clicking "Learn" could get captured as the transport mapping, and fixed MIDI keys/pads going silent after a mapping change (MIDI init is now idempotent)
- New 16-pad soundboard with drag-and-drop custom samples per pad, right-click pad editor (name, volume, MIDI note, loop toggle), and a separate movable Pads window
- 7 built-in preset kits, one click to fill all 16 pads: 🥁 Drums, 🔊 808, 📻 Lo-Fi (real recorded drum-machine samples with automatic offline fallback), 🎹 Piano, 🎸 Guitar, 🎛 Synth keys, 🎉 Sound FX (crowd cheer/boo, applause, airhorn, laugh, and more)
- Fixed pads and the synth not being captured in stream/loop recordings — they were previously audible live but silent in anything recorded
- Redesigned the transport from one ambiguous multi-function pad into 4 explicit buttons — ● Record, ▶ Play, ❚❚ Stop/Pause, ✕ Clear — so it's always clear what a press will do, per track
- Added quantized recording start: Record/Overdub now snap to the beat grid instead of starting the instant you press the button, with a default of 1/4-bar (one beat) and a per-track dial to pick Off / Auto / 1/4 / 1/8 / 1/16 / 1/32
- Fixed silent/incomplete loop recordings — recording now taps a dedicated bus that bypasses Cue muting so it always captures exactly what's audible, regardless of a channel's monitor-only state
- Fixed a MIDI hardware transport bug where a single Record/Play button press was firing twice (start-then-stop) because CC messages fire on both button-down and button-up
- Per-track bar length + quantize dials, per-track level fader, tap-tempo, and a live fill-ring on the Record button showing progress toward auto-stop
- Real-time pitch shifter and autotune on the mic signal (Sounds → FX pane) — manual semitone shift or auto snap-to-scale/key correction with adjustable correction strength, so your voice (not just pads/synth) can be tuned before it reaches listeners
- Fixed background X tabs staying pinned at full, unthrottled CPU/GPU forever, which caused the whole app to slow down the longer you had multiple tabs open — only the currently visible tab is now kept unthrottled
- Added crash/hang recovery for X tabs: an unresponsive-page banner with a one-click Reload, and automatic tab recreation if X's renderer crashes, instead of a permanently frozen tab
- Granted MIDI/MIDI-Sysex permissions so hardware controllers work inside X tabs as well as the mixer
- Removed the redundant ✕ close buttons from the Pads and Loop Station popup windows — they already hide automatically when you switch away from the Sounds tab
- Kept x.com on the proven BrowserView path with no background throttling on active X views
- Removed non-x.com broadcast relay path (legacy Suno-era integration) to reduce audio-side side effects
- Gear open/close now behaves as a UI visibility/editor flow and no longer forces automatic graph reapply
- Added sender-track self-heal safeguards for stale ended tracks without requiring a full manual rebuild
- Improved default app behavior so X remains the primary tab experience
- Restored stripping of
Cross-Origin-Embedder-Policy,Cross-Origin-Opener-Policy, andCross-Origin-Resource-Policyheaders for x.com — scoped to x.com/twitter.com only (other sites keep their headers).COEP: require-corpwas blocking X Spaces' cross-origin CDN audio/avatar resources, causing the speaker list to be empty and the Space connection to fail - Matches v0.5.0's proven header-stripping behaviour exactly
- GitHub Actions CI now produces three release artifacts on every tag:
XCaster-win32-x64.zip,XCaster-darwin-arm64.zip(Apple Silicon),XCaster-darwin-x64.zip(Intel)
- x.com now loads in a BrowserView with
preload.js— identical to v0.5.0's architecture.getUserMediais patched before any X scripts run, so the DSP graph and X'sRTCPeerConnectionshare the same renderer context - Removed SDP patching (
patchOpusSdp) from X's ownRTCPeerConnection— forcing stereo/510kbps/CBR/no-DTX on X's outbound connection caused X's media servers to reject the SDP, showing the host as muted and disconnected to listeners - Fullscreen and maximise now resize the BrowserView correctly — listening to
maximize,unmaximize,enter-full-screen,leave-full-screen,enter-html-full-screen,leave-html-full-screenin addition toresize - Removed
setAutoResizewhich conflicted with manualsetBoundscalls and caused misalignment - Fixed
BrowserView is not definedcrash —BrowserViewwas missing from the Electron import destructure
- DSP graph is now built directly inside X's webview context (same as v0.5.0) — single Opus encode, no relay
- Chrome WebRTC AGC disabled at capture time via
applyConstraints(autoGainControl / noiseSuppression / echoCancellation all off) - Loopback bleed from Cable Output fixed — raw mic fallback no longer occurs
The mixer gear now lives in the app itself, not inside a specific tab. It opens instantly with no tabs loaded and stays accessible regardless of what page you're on.
Every browser tab in XCaster is automatically muted from your system output (virtual cable, speakers, everything) the moment it loads. Their audio is captured directly via the Electron frame API and fed exclusively into the xCaster channel in the mixer — completely bypassing your PC's audio devices.
- No tab audio leaks to your virtual cable or Aux inputs
- No feedback loop when Aux 1 and xCaster are both monitored
- New tabs are captured automatically as you open them
- Multiple tabs mix together in the xCaster channel pre-gain
suppressLocalAudioPlaybackis honoured at the frame level — the OS never sees the audio
- Gear opens on any tab — or even with no tabs open
- Monitor, Cue, Mute, and level controls all work independently of which page is active
- xCaster channel plays to your selected speaker output only — not to PC default
- WebRTC AGC disabled — X Spaces cannot auto-level, duck, or re-process your microphone
- 4-channel mixer — Mic + Aux 1 + Aux 2 + xCaster (in-app tab audio), all summed pre-DSP
- xCaster channel — captures all open tabs simultaneously, isolated from system audio
- Per-channel controls — Level, Mute, Monitor in headset, Cue (PFL) per channel
- Cue (PFL) — audition a channel in your headset without sending it to X
- Output routing — monitor bus and X Spaces playback routed to your chosen output device via
AudioContext.setSinkId - Full DSP chain — High-pass filter → 3-band EQ → Compressor → Limiter → Makeup gain
- Live meters — Mic / Aux 1 / Aux 2 / xCaster / Mix / Out / Gain Reduction
- Background audio stability — Chromium background throttling disabled; Web Worker keepalive prevents choppy audio when minimized
- Built-in browser — tabs for X, YouTube, TibetSwap, MintGarden, and your custom bookmarks
- Background skin —
background.mp4plays behind a semi-transparent content window - Draggable UI — drag the gear anywhere on screen
- Presets — Spaces loud+steady / Podcast / Music / Off (raw bypass)
- Persists settings — all knobs saved in localStorage between sessions
cd XForWindows
npm install
npm startcd XForWindows
npm install
npm run packageOutput: XForWindows/dist/XCaster-win32-x64/XCaster.exe
- Launch XCaster.exe
- Click the ⚙ gear button (bottom-right, or wherever you dragged it) — works with or without tabs open
- Mic tab — pick your microphone, set level
- Aux 1 / Aux 2 tabs — optionally pick desktop audio or an external source
- xCaster tab — shows how many tabs are captured; use Mute / Monitor / Cue / Level to control them
- Speakers tab — pick where the monitor bus plays (headphones, to avoid feedback)
- Processing tab — tune HPF, EQ, compressor, limiter
- Skin tab — background video, content opacity, drag positions
- Presets tab — one-click starting points
Press Ctrl+, to toggle the panel at any time.
[Mic] ──────────────────┐
[Aux 1 (virtual cable)] ├──► per-channel Gain ──► mixBus ──► DSP ──► X Spaces (getUserMedia)
[Aux 2 (ext. mixer)] ───┤
[xCaster (all tabs)] ───┘
monitorBus ──► AudioContext.setSinkId ──► selected headset
Tab audio never touches the system audio device. The virtual cable on Aux 1 only captures what you explicitly route there — not xCaster tab audio.
Desktop X in Chrome/Edge forces WebRTC AGC onto every mic with no UI toggle. XCaster launches with Chromium flags that disable the audio service APM, patches getUserMedia so X receives a flat signal, and adds a full DSP chain with metering so you control your sound — not X's algorithm.
- Windows 10/11 x64
- No virtual cable required (optional for routing from external apps into Aux 1/2)