Audio capture and streaming app for webOS 5/6

Captures the TV's audio and sends it out over several transports. The
primary one is HyperHDR: RTP/L16 to a host-side loopback device, since
HyperHDR has no network audio input of its own. A second route renders
the spectrum on the TV and sends FlatBuffers images to port 19400
instead, for setups where touching the host's sound config is not an
option.

  native/       the service: capture backends (PulseAudio, ALSA, exec,
                test tone, all dlopen-based), DSP, and one file per sink
  frontend/     D-pad driven UI at a fixed 1920x1080
  servicefiles/ native service manifest plus the boot script
  host/         RTP receiver and the loopback installer for the HyperHDR
                machine
  tools/        build/package, asset generation, Homebrew Channel
                manifest, on-TV probe
  test/         host-side suites: FlatBuffers and RTP verified against
                real decoders, the engine end to end, the page in jsdom

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

frontend/js/luna.js

@@ -0,0 +1,132 @@
+// Luna bus access.
+//
+// Talks to PalmServiceBridge directly rather than pulling in webOSTV.js: it is
+// the same object webOSTV.js wraps, it is injected into every webOS app, and
+// it means there is no third-party file to keep in sync.
+//
+// Opened in a desktop browser the bridge is absent, so everything falls back
+// to a small mock. That is what makes the UI developable without a TV.
+
+(function (global) {
+  'use strict';
+
+  var SERVICE = 'luna://org.webosbrew.audiocap.service/';
+  var HBCHANNEL = 'luna://org.webosbrew.hbchannel.service/';
+
+  var haveBridge = typeof global.PalmServiceBridge !== 'undefined';
+
+  // A call in flight. `cancel()` tears down a subscription.
+  function Request(bridge) {
+    this.bridge = bridge;
+    this.cancelled = false;
+  }
+
+  Request.prototype.cancel = function () {
+    this.cancelled = true;
+    if (this.bridge && this.bridge.cancel) {
+      this.bridge.cancel();
+    }
+  };
+
+  // Low-level call. `onReply` fires once per reply, so subscriptions keep
+  // calling it until cancelled.
+  function call(uri, params, onReply, onError) {
+    if (!haveBridge) {
+      return global.LunaMock.call(uri, params, onReply, onError);
+    }
+
+    var bridge = new global.PalmServiceBridge();
+    var request = new Request(bridge);
+
+    bridge.onservicecallback = function (raw) {
+      if (request.cancelled) {
+        return;
+      }
+      var reply;
+      try {
+        reply = JSON.parse(raw);
+      } catch (e) {
+        if (onError) {
+          onError('Malformed reply from ' + uri);
+        }
+        return;
+      }
+      // Luna reports both its own failures and ours through returnValue.
+      if (reply.returnValue === false) {
+        if (onError) {
+          onError(reply.errorText || reply.errorMessage || 'Call to ' + uri + ' failed');
+        }
+        return;
+      }
+      if (onReply) {
+        onReply(reply);
+      }
+    };
+
+    try {
+      bridge.call(uri, JSON.stringify(params || {}));
+    } catch (e) {
+      if (onError) {
+        onError(String(e));
+      }
+    }
+    return request;
+  }
+
+  var Luna = {
+    available: haveBridge,
+
+    // --- our service -------------------------------------------------------
+    start: function (patch, ok, fail) {
+      return call(SERVICE + 'start', patch || {}, ok, fail);
+    },
+    stop: function (ok, fail) {
+      return call(SERVICE + 'stop', {}, ok, fail);
+    },
+    subscribeStatus: function (ok, fail) {
+      return call(SERVICE + 'getStatus', { subscribe: true }, ok, fail);
+    },
+    getConfig: function (ok, fail) {
+      return call(SERVICE + 'getConfig', {}, ok, fail);
+    },
+    setConfig: function (patch, ok, fail) {
+      return call(SERVICE + 'setConfig', { settings: patch }, ok, fail);
+    },
+    resetConfig: function (ok, fail) {
+      return call(SERVICE + 'resetConfig', {}, ok, fail);
+    },
+    listBackends: function (ok, fail) {
+      return call(SERVICE + 'listBackends', {}, ok, fail);
+    },
+    listSinks: function (ok, fail) {
+      return call(SERVICE + 'listSinks', {}, ok, fail);
+    },
+    getDiagnostics: function (ok, fail) {
+      return call(SERVICE + 'getDiagnostics', {}, ok, fail);
+    },
+    // Ends the service process. Any later call starts a fresh one, which is
+    // how the service picks up new bus permissions after being elevated.
+    quit: function (ok, fail) {
+      return call(SERVICE + 'quit', {}, ok, fail);
+    },
+    // `clear` empties the ring buffer after reading it, so the reply is the
+    // last thing anyone sees of those lines.
+    getLogs: function (clear, ok, fail) {
+      return call(SERVICE + 'getLogs', { clear: !!clear }, ok, fail);
+    },
+
+    // --- Homebrew Channel --------------------------------------------------
+    // Used for the boot symlink. Needs the Homebrew Channel installed, which
+    // it will be on any TV that can run this app.
+    exec: function (command, ok, fail) {
+      return call(HBCHANNEL + 'exec', { command: command }, ok, fail);
+    },
+
+    // --- system ------------------------------------------------------------
+    getNetworkStatus: function (ok, fail) {
+      return call('luna://com.palm.connectionmanager/getStatus', {}, ok, fail);
+    },
+  };
+
+  global.Luna = Luna;
+})(window);