s&box ships a complete, networked microphone/voice system — you do **not** need to hand-roll Steam voice capture, Opus transmission, or 3D playback. It is one engine component: `Sandbox.Voice`. ## 1. The component surface `Voice` (`public class Voice : Component`) records and transmits voice/microphone input to other players. Attach one per player object. The full API surface: | Member | Meaning | |---|---| | `enum ActivateMode { AlwaysOn, PushToTalk, Manual }` | How the mic keys on. | | `ActivateMode Mode` | Default **AlwaysOn** — you almost always want `PushToTalk`. | | `string PushToTalkInput` | InputAction name; default `"voice"`. Held while `Mode == PushToTalk`. | | `bool WorldspacePlayback` | Default **true** — 3D positional playback at the component's `WorldPosition`, with occlusion. `false` = 2D `ListenLocal`. | | `bool Loopback` | Default `false` = don't play the sound of your own voice. | | `float Volume` | Default 1. | | `float Distance` | Default **15,000 units (about 381 m)** — max attenuation distance. | | `Curve Falloff` | Normalized distance `0..1` (where 1 = `Distance`) mapped to gain. The default curve is heavily front-loaded — wrong for a tight proximity bubble. | | `bool LipSync` / `SkinnedModelRenderer Renderer` / `MorphScale` / `MorphSmoothTime` | Drives citizen viseme morphs from the live voice analysis. Safely no-ops if `Renderer` is invalid. | | `RealTimeSince LastPlayed` | Resets to 0 on every received voice packet — the cleanest "is this player speaking" signal on a proxy. | | `bool IsRecording` / `bool IsListening` | Local capture state. `IsListening` is the preference-gated truth. | | `float Amplitude` | Live loudness of the playback sound. | | `MixerHandle VoiceMixer` | Target mixer; must descend from `Mixer.Voice`. A user "voice volume" slider hooks here. | | `float LaughterScore` / `IReadOnlyList Visemes` | Analysis outputs. | | `virtual IEnumerable ExcludeFilter()` | Override to per-player MUTE (exclude connections from hearing you). | | `virtual bool ShouldHearVoice(Connection)` | Override to per-player DEAFEN (drop a speaker). | **Networking is built in.** The component transmits via `[Rpc.Broadcast(NetFlags.OwnerOnly | NetFlags.UnreliableNoDelay)]` — the owner records (Steam voice, 44.1 kHz, ~30 Hz read tick), compresses, and broadcasts; receiving peers decompress and play through a `SoundStream`. `IsListening` returns `false` when `IsProxy`, so a peer only ever transmits its own character. `Application.IsHeadless` short-circuits playback — a dedicated server is silent; voice relays peer-to-peer via the broadcast. A static `singleRecorder` ensures only one Voice records per client. ## 2. The wiring recipe Two rules carry the whole feature: **Rule A — attach to the networked player object BEFORE `NetworkSpawn`.** The component rides the replicated snapshot to every peer (the component-ordering law: create components, then `NetworkSpawn`). Attach only in the networked path — a solo character gets no Voice, giving zero mic activity in single-player with no null-guards needed: ```csharp var go = Scene.CreateObject(); var chr = go.Components.Create(); if ( owner is not null ) { go.Components.Create(); // BEFORE NetworkSpawn go.NetworkSpawn( owner ); } ``` **Rule B — configure on every peer, not via replication.** Playback config on a proxy comes from that peer's own `OnStart`, not the snapshot. Set `Mode`, `Distance`, `Falloff`, and `PushToTalkInput` on every peer: ```csharp protected override void OnStart() { var voice = Components.Get(); if ( !voice.IsValid() ) return; // solo mode — no Voice attached voice.Mode = Voice.ActivateMode.PushToTalk; voice.PushToTalkInput = "Voice"; voice.WorldspacePlayback = true; voice.LipSync = true; voice.Distance = VoiceMaxRangeM * 39.37f; // metres → s&box units float nearRatio = VoiceNearRangeM / VoiceMaxRangeM; voice.Falloff = new Curve( new Curve.Frame( 0f, 1f, 0f, 0f ), new Curve.Frame( nearRatio, 1f, 0f, 0f ), new Curve.Frame( 1f, 0f, 0f, 0f ) ); voice.Renderer = Components.Get(); } ``` `Curve(params Frame[])` and `Curve.Frame(time, value, inTangent, outTangent)` are public. **Do not ship the default `Falloff` + `Distance`** for proximity chat — 381 m of range with the stock curve gives a mushy, map-spanning whisper instead of a crisp local bubble. ## 3. Push-to-talk: three layers 1. **The engine user preference is already PTT by default.** `Preferences.VoiceMode` (ConVar `voip_mode`, saved) defaults to `PushToTalk`. The `IsListening` logic: `Disabled` never transmits; `PushToTalk` always requires `Input.Down(PushToTalkInput)` regardless of component Mode; `OpenMicrophone` honors the component Mode. 2. **Bind the built-in `"Voice"` input action.** Every project's `ProjectSettings/Input.config` typically ships a `"Voice"` action (often with `KeyboardCode: None`); the component's default `PushToTalkInput = "voice"` binds to it — assign a free key and you're done. **Verify it exists** — not every project has it. If missing, add it to `Input.config` (editor restart required for input config changes to register). 3. **Set component `Mode = PushToTalk` anyway** (belt-and-suspenders): keeps PTT gating even for a user whose saved `voip_mode` is `OpenMicrophone` — without it, that user would hot-mic your game. ## 4. The speaking-indicator pattern On a proxy, `voice.LastPlayed < holdSeconds` is a flicker-free "speaking" flag: packets arrive ~30/s while the mic is active, so a **~0.3 s hold window** bridges inter-packet gaps and clears shortly after the talker stops: ```csharp var voice = chr.Components.Get(); bool speaking = voice.IsValid() && voice.LastPlayed < 0.3f; ``` **Anchor the tag off the networked transform, not an owner-only sim field.** A proxy (the only character you tag) never runs the owner's `OnFixedUpdate`, so any private position field written there (and not `[Sync]`) freezes at the proxy's spawn value while the replicated `GameObject.WorldPosition` carries the real player. Anchor the tag off a frozen field and it strands at spawn while the model walks away. Read the character's `WorldPosition` (the same interpolated source the parented visual renders from) — it also satisfies the read-interpolated-transforms rule. In a live two-peer session, a tag anchored to an unsynced owner field was observed hanging over the spawn area while the player model stood elsewhere; switching to `WorldPosition` fixed it immediately. For a Razor name-tag overlay, fold the flag into `BuildHash` so the DOM rebuilds only on a state change, not per frame. `Components.Get()` returns null on a non-networked character, so `speaking = false` gives the correct solo behavior for free. ## 5. Falloff radii as tuning constants House the radii as named constants in metres with doc comments; convert once at emission (s&box units are inches; 1 m = 39.37 units): ```csharp public const float VoiceNearRangeM = 8f; // full-volume conversational core public const float VoiceMaxRangeM = 35f; // silent at/beyond public const float VoiceSpeakingHoldS = 0.3f; // indicator hold window ``` These are live-tuning dials: the "how far can I hear them" feel can only be judged in a real two-peer session. Scale to your world footprint; the engine default (381 m) is effectively "everywhere" on a small map. ## 6. Extension points - **Per-player mute:** subclass (`class MyVoice : Voice`) overriding `ExcludeFilter()` to yield the connections that should not hear you (applied via `Rpc.FilterExclude` around the broadcast). - **Per-player deafen:** override `ShouldHearVoice(Connection)` to return `false` for speakers the local user muted. - **Lip-sync:** set `Renderer` to the peer's `SkinnedModelRenderer` — the engine drives citizen viseme morphs from the live analysis, holds the shape through packet gaps, and eases out after ~1 s. If the model lacks viseme morphs, `LipSync` safely no-ops. - **Team voice / screen-space stereo:** `WorldspacePlayback = false` puts the sound in screen space for team-left/right audio. - **Occlusion:** enabled by default in worldspace playback. Only avoidable via a subclass override if terrain-muffled voice is wrong for your game. - **Mixer routing:** `VoiceMixer` targets any descendant of the `Voice` mixer — the hook for a user voice-volume slider (don't repurpose `Volume` for that). ## 7. The two-peer verification checklist Run once per project after wiring. Each row should be proven live: | # | Check | |---|---| | 1 | Host + joiner in session, both possessed, name tags visible both ways | | 2 | Hold PTT → other peer hears audio; speaking indicator lights; release → audio stops, indicator clears within the hold window. Both directions. | | 3 | No self-hearing while transmitting | | 4 | Falloff: walk away — clearly audible inside the near core, fading, silent by max range | | 5 | Directionality: circle the speaker → voice pans; walk behind terrain → occlusion muffling | | 6 | Lip-sync: speaker's citizen mouth visibly moves while talking | | 7 | Solo sanity: single-player session has zero mic activity, zero errors | Check #2 is the keystone — it proves the create-before-NetworkSpawn premise (that a proxy's `Msg_Voice` RPC arrives and plays). Everything upstream of #2 is compile-proven only. ## 8. Pitfalls | ID | Pitfall | |---|---| | P1 | Component default `Mode` is **AlwaysOn** — a bare `Voice` relies entirely on the user's `voip_mode` preference. Always set `PushToTalk` explicitly. | | P2 | Default `Distance` (381 m) and the default `Falloff` are wrong for proximity chat. Set both, with a tangent-0 plateau curve. | | P3 | Playback config on a proxy comes from that peer's own `OnStart`, not replication — configure on every peer. | | P4 | The `"Voice"` input action is usually but **not always** present in `Input.config`. Always verify; if missing, add it (editor restart required). | | P5 | Dedicated server: `Application.IsHeadless` mutes playback — no server-side audio work needed. | | P6 | Solo sessions: attach Voice only in the networked spawn path. This guarantees zero mic activity in single-player and makes `Get() == null` the solo gate. | | P7 | A sibling-component pattern works when the character class is frozen: create a new component alongside Voice on the same GameObject and configure the sibling in `OnStart`. No character edits needed. | | P8 | If the `SkinnedModelRenderer` lives on a child GameObject, use `Components.Get(FindMode.EnabledInSelfAndDescendants)` with a one-tick lazy retry (component start ordering isn't guaranteed). |

#session-lifecycle