From 6f2cc9cfeba02cfeff453d0267d91e3ea93ace2c Mon Sep 17 00:00:00 2001
From: Ken Cooke <ken@highfidelity.io>
Date: Wed, 9 Aug 2017 14:01:17 -0700
Subject: [PATCH] When no input device, create dummy input to generate
 callbacks

---
 libraries/audio-client/src/AudioClient.cpp | 22 ++++++++++++++++++++++
 libraries/audio-client/src/AudioClient.h   |  1 +
 2 files changed, 23 insertions(+)

diff --git a/libraries/audio-client/src/AudioClient.cpp b/libraries/audio-client/src/AudioClient.cpp
index bc02da1cc4..4ec89b6fa3 100644
--- a/libraries/audio-client/src/AudioClient.cpp
+++ b/libraries/audio-client/src/AudioClient.cpp
@@ -160,6 +160,7 @@ AudioClient::AudioClient() :
     AbstractAudioInterface(),
     _gate(this),
     _audioInput(NULL),
+    _dummyAudioInput(NULL),
     _desiredInputFormat(),
     _inputFormat(),
     _numInputCallbackBytes(0),
@@ -1423,11 +1424,19 @@ bool AudioClient::switchInputToAudioDevice(const QAudioDeviceInfo& inputDeviceIn
         _inputDeviceInfo = QAudioDeviceInfo();
     }
 
+    if (_dummyAudioInput) {
+        _dummyAudioInput->stop();
+
+        _dummyAudioInput->deleteLater();
+        _dummyAudioInput = NULL;
+    }
+
     if (_inputToNetworkResampler) {
         // if we were using an input to network resampler, delete it here
         delete _inputToNetworkResampler;
         _inputToNetworkResampler = NULL;
     }
+
     if (_audioGate) {
         delete _audioGate;
         _audioGate = nullptr;
@@ -1485,6 +1494,19 @@ bool AudioClient::switchInputToAudioDevice(const QAudioDeviceInfo& inputDeviceIn
         }
     }
 
+    // If there is no input device, use the dummy input device.
+    // It generates audio callbacks on a timer to simulate a mic stream of silent packets.
+    // This enables clients without a mic to still receive an audio stream from the mixer.
+    if (!_audioInput) {
+        qCDebug(audioclient) << "No audio input device is available, using dummy input.";
+
+        QTimer* _dummyAudioInput = new QTimer(this);
+        //connect(_dummyAudioInput, &QTimer::timeout, this, SLOT(handleDummyAudioInput()));
+
+        // generate audio callbacks at the network sample rate
+        _dummyAudioInput->start((int)(AudioConstants::NETWORK_FRAME_MSECS + 0.5f));
+    }
+
     return supportedFormat;
 }
 
diff --git a/libraries/audio-client/src/AudioClient.h b/libraries/audio-client/src/AudioClient.h
index 1c26b1bb08..a93ee5e515 100644
--- a/libraries/audio-client/src/AudioClient.h
+++ b/libraries/audio-client/src/AudioClient.h
@@ -277,6 +277,7 @@ private:
 
     Mutex _injectorsMutex;
     QAudioInput* _audioInput;
+    QTimer* _dummyAudioInput;
     QAudioFormat _desiredInputFormat;
     QAudioFormat _inputFormat;
     QIODevice* _inputDevice;