From 4cfd54b21b67333eec1026e8d687e51b1788ffc3 Mon Sep 17 00:00:00 2001
From: Volker Fischer <corrados@users.noreply.github.com>
Date: Sun, 29 Mar 2020 18:03:24 +0200
Subject: [PATCH] audio fade-in at the server if new client connects

---
 ChangeLog       |  3 ++-
 src/channel.cpp | 10 ++++++++++
 src/channel.h   | 14 +++++++++++++-
 src/server.cpp  | 15 +++++++--------
 4 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index c046813f..6eebf3ed 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -4,10 +4,11 @@
 
 - changed the maximum number of clients from 20 to 40
 
+- audio fade-in at the server if new client connects
+
 
 TODO add a QScrollArea to the mixer board to get a scroll bar if we have too many mixer faders
 
-TODO slowly fade in the audio at the server for all inputs of client which new connects to the server and also if new other client enters the server
 
 
 
diff --git a/src/channel.cpp b/src/channel.cpp
index 8dcd597d..bebdf501 100755
--- a/src/channel.cpp
+++ b/src/channel.cpp
@@ -29,6 +29,7 @@
 CChannel::CChannel ( const bool bNIsServer ) :
     vecdGains          ( MAX_NUM_CHANNELS, 1.0 ),
     bDoAutoSockBufSize ( true ),
+    iFadeInCnt         ( 0 ),
     bIsEnabled         ( false ),
     bIsServer          ( bNIsServer )
 {
@@ -461,6 +462,12 @@ EPutDataStat CChannel::PutAudioData ( const CVector<uint8_t>& vecbyData,
                 {
                     eRet = PS_AUDIO_ERR;
                 }
+
+                // manage audio fade-in counter
+                if ( iFadeInCnt < FADE_IN_NUM_FRAMES )
+                {
+                    iFadeInCnt++;
+                }
             }
             else
             {
@@ -481,6 +488,9 @@ EPutDataStat CChannel::PutAudioData ( const CVector<uint8_t>& vecbyData,
             {
                 // overwrite status
                 eRet = PS_NEW_CONNECTION;
+
+                // init audio fade-in counter
+                iFadeInCnt = 0;
             }
 
             // reset time-out counter (note that this must be done after the
diff --git a/src/channel.h b/src/channel.h
index 618c02f0..1f855877 100755
--- a/src/channel.h
+++ b/src/channel.h
@@ -36,11 +36,21 @@
 
 
 /* Definitions ****************************************************************/
-// Set the time-out for the input buffer until the state changes from
+// set the time-out for the input buffer until the state changes from
 // connected to not connected (the actual time depends on the way the error
 // correction is implemented)
 #define CON_TIME_OUT_SEC_MAX                30 // seconds
 
+// number of frames for audio fade-in
+#if ( SYSTEM_FRAME_SIZE_SAMPLES == 64 )
+// 48 kHz, 64 samples: 2 seconds / ( 64 samples / 48 kHz ) = 2250
+# define FADE_IN_NUM_FRAMES                 1500
+#else
+// 48 kHz, 128 samples: 2 seconds / ( 128 samples / 48 kHz ) = 1125
+# define FADE_IN_NUM_FRAMES                 750
+#endif
+
+
 enum EPutDataStat
 {
     PS_GEN_ERROR,
@@ -103,6 +113,7 @@ public:
 
     void SetGain ( const int iChanID, const double dNewGain );
     double GetGain ( const int iChanID );
+    double GetFadeInGain() { return static_cast<double> ( iFadeInCnt ) / FADE_IN_NUM_FRAMES; }
 
     void SetRemoteChanGain ( const int iId, const double dGain )
         { Protocol.CreateChanGainMes ( iId, dGain ); }
@@ -190,6 +201,7 @@ protected:
 
     int               iConTimeOut;
     int               iConTimeOutStartVal;
+    int               iFadeInCnt;
 
     bool              bIsEnabled;
     bool              bIsServer;
diff --git a/src/server.cpp b/src/server.cpp
index 5ddc2df3..fd8af258 100755
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -833,10 +833,8 @@ JitterMeas.Measure();
             const int iCurChanID = vecChanIDsCurConChan[i];
 
             // get and store number of audio channels
-            const int iCurNumAudChan =
-                vecChannels[iCurChanID].GetNumAudioChannels();
-
-            vecNumAudioChannels[i] = iCurNumAudChan;
+            const int iCurNumAudChan = vecChannels[iCurChanID].GetNumAudioChannels();
+            vecNumAudioChannels[i]   = iCurNumAudChan;
 
             // get gains of all connected channels
             for ( j = 0; j < iNumClients; j++ )
@@ -845,13 +843,14 @@ JitterMeas.Measure();
                 // the channel ID! Therefore we have to use
                 // "vecChanIDsCurConChan" to query the IDs of the currently
                 // connected channels
-                vecvecdGains[i][j] =
-                    vecChannels[iCurChanID].GetGain( vecChanIDsCurConChan[j] );
+                vecvecdGains[i][j] = vecChannels[iCurChanID].GetGain ( vecChanIDsCurConChan[j] );
+
+                // consider audio fade-in
+                vecvecdGains[i][j] *= vecChannels[vecChanIDsCurConChan[j]].GetFadeInGain();
             }
 
             // get current number of CELT coded bytes
-            const int iCeltNumCodedBytes =
-                vecChannels[iCurChanID].GetNetwFrameSize();
+            const int iCeltNumCodedBytes = vecChannels[iCurChanID].GetNetwFrameSize();
 
             // get data
             const EGetDataStat eGetStat =