From 9319eb49b78a34b4c9a7a5d5a6ba7d95c430424f Mon Sep 17 00:00:00 2001
From: Matthew Stratford <hi@mstratford.net>
Date: Sun, 24 Jan 2021 21:43:51 +0000
Subject: [PATCH] Fix fading to silent, and PFL metering.

---
 src/mixer/audio.ts |  9 ++++++---
 src/mixer/state.ts | 15 +++++++++------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/mixer/audio.ts b/src/mixer/audio.ts
index 14c25a4..900ef3a 100644
--- a/src/mixer/audio.ts
+++ b/src/mixer/audio.ts
@@ -8,6 +8,7 @@ import NewsEndCountdown from "../assets/audio/NewsEndCountdown.wav";
 import NewsIntro from "../assets/audio/NewsIntro.wav";
 
 import StereoAnalyserNode from "stereo-analyser-node";
+import { DEFAULT_TRIM_DB, OFF_LEVEL_DB } from "./state";
 
 interface PlayerEvents {
   loadComplete: (duration: number) => void;
@@ -164,8 +165,10 @@ class Player extends ((PlayerEmitter as unknown) as { new (): EventEmitter }) {
   }
 
   _applyVolume() {
-    const level = this.volume + this.trim;
-    const linear = Math.pow(10, level / 20);
+    const log = this.volume + this.trim;
+
+    // If we're down at the "off level", pure mute it, else, do the linear conversion.
+    let linear = this.volume === OFF_LEVEL_DB ? 0 : Math.pow(10, log / 20);
 
     // Actually adjust the wavesurfer gain node gain instead, so we can tap off analyser for PFL.
     this.wavesurfer.setVolume(1);
@@ -461,7 +464,7 @@ export class AudioEngine extends ((EngineEmitter as unknown) as {
     this.newsEndCountdownNode.connect(this.audioContext.destination);
 
     // Send the headphones feed to the headphones.
-    const db = -12; // DB gain on headphones (-6 to match default trim)
+    const db = DEFAULT_TRIM_DB; // DB gain on headphones (match default trim)
     this.headphonesNode.gain.value = Math.pow(10, db / 20);
     this.headphonesNode.connect(this.audioContext.destination);
     this.headphonesNode.connect(this.pflAnalyser);
diff --git a/src/mixer/state.ts b/src/mixer/state.ts
index 48c95b7..3081d89 100644
--- a/src/mixer/state.ts
+++ b/src/mixer/state.ts
@@ -28,8 +28,11 @@ type VolumePresetEnum = "off" | "bed" | "full";
 type MicVolumePresetEnum = "off" | "full";
 export type MicErrorEnum = "NO_PERMISSION" | "NOT_SECURE_CONTEXT" | "UNKNOWN";
 
-const defaultTrimDB = -6; // The default trim applied to channel players.
+export const DEFAULT_TRIM_DB = -6; // The default trim applied to channel players.
 
+export const OFF_LEVEL_DB = -40;
+export const BED_LEVEL_DB = -13;
+export const FULL_LEVEL_DB = 0;
 interface PlayerState {
   loadedItem: PlanItem | Track | AuxItem | null;
   loading: number;
@@ -72,7 +75,7 @@ const BasePlayerState: PlayerState = {
   volumeEnum: "full",
   gain: 0,
   micAutoDuck: false,
-  trim: defaultTrimDB,
+  trim: DEFAULT_TRIM_DB,
   pfl: false,
   timeCurrent: 0,
   timeRemaining: 0,
@@ -125,7 +128,7 @@ const mixerState = createSlice({
       if (action.payload.customOutput) {
         state.players[action.payload.player].trim = 0;
       } else if (action.payload.resetTrim) {
-        state.players[action.payload.player].trim = defaultTrimDB;
+        state.players[action.payload.player].trim = DEFAULT_TRIM_DB;
       }
     },
     itemLoadPercentage(
@@ -702,15 +705,15 @@ export const setVolume = (
   let uiLevel: number;
   switch (level) {
     case "off":
-      volume = -40;
+      volume = OFF_LEVEL_DB; // The sweet spot for getting below the silence rounding in audio.ts -> _applyVolume()
       uiLevel = 0;
       break;
     case "bed":
-      volume = -13;
+      volume = BED_LEVEL_DB;
       uiLevel = 0.5;
       break;
     case "full":
-      volume = 0;
+      volume = FULL_LEVEL_DB;
       uiLevel = 1;
       break;
   }