[dasher] Add FrameRate.cpp which was missing from

[Patrick Welche <pwelche src gnome org>]

commit 22dea93557ba432d6cf9a8f65d60c04d430889b6
Author: Alan Lawrence <acl33 inf phy cam ac uk>
Date:   Wed Jun 17 16:17:50 2009 +0100

    Add FrameRate.cpp which was missing from
    2009-06-16  Alan Lawrence <acl33 inf phy cam ac uk>
    and add missing ChangeLog.

 Src/DasherCore/FrameRate.cpp |   78 ++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 78 insertions(+), 0 deletions(-)
---
diff --git a/Src/DasherCore/FrameRate.cpp b/Src/DasherCore/FrameRate.cpp
new file mode 100644
index 0000000..4c4fe6a
--- /dev/null
+++ b/Src/DasherCore/FrameRate.cpp
@@ -0,0 +1,78 @@
+#include "FrameRate.h"
+
+CFrameRate::CFrameRate(CEventHandler *pEventHandler, CSettingsStore *pSettingsStore) :
+  CDasherComponent(pEventHandler, pSettingsStore) {
+
+  //what follows was once the Initialise() method, but
+  // (ACL 21/05/09) is no longer called from elsewhere, hence inlining
+  m_dRXmax = 2;                 // only a transient effect
+  m_iFrames = 0;
+  m_iSamples = 1;
+
+  // start off very slow until we have sampled framerate adequately
+  m_iSteps = 2000;
+  m_iTime = 0;                  // Hmmm, User must reset framerate before starting.
+
+  //Set bitrate and framerate
+  m_dFr = GetLongParameter(LP_FRAMERATE) / 100.0;
+  m_dMaxbitrate = GetLongParameter(LP_MAX_BITRATE) * GetLongParameter(LP_BOOSTFACTOR) / 10000.0;
+}
+
+void CFrameRate::NewFrame(unsigned long Time)
+{
+  m_iFrames++;
+
+  // Update values once enough samples have been collected
+  if(m_iFrames == m_iSamples) {
+    m_iTime2 = Time;
+
+    // If samples are collected in < 50ms, collect more
+    if(m_iTime2 - m_iTime < 50)
+      m_iSamples++; 
+    // And if it's taking longer than > 80ms, collect fewer, down to a
+    // limit of 2
+    else if(m_iTime2 - m_iTime > 80) {
+      m_iSamples--;
+      if(m_iSamples < 2)
+        m_iSamples = 2;
+    }
+
+    // Calculate the framerate and reset framerate statistics for next
+    // sampling period
+    if(m_iTime2 - m_iTime > 0) {
+      SetLongParameter(LP_FRAMERATE, m_iFrames * 100000.0 / (m_iTime2 - m_iTime));
+      m_iTime = m_iTime2;
+      m_iFrames = 0;
+    }
+
+    // Update auxiliary variables - even if we didn't recalc the framerate
+    //   (means we reach sensible values more quickly after first loading)
+    m_dRXmax = exp(m_dMaxbitrate * LN2 / m_dFr);
+    
+    // Note that m_iSteps is smoothed here - 50:50 interpolation with
+    // previous value
+    m_iSteps = m_iSteps / 2 + (int)(-log(0.2) * m_dFr / LN2 / m_dMaxbitrate) / 2;
+
+    // If the framerate slows to < 4 then we end up with steps < 1 ! 
+    if(m_iSteps == 0)
+      m_iSteps = 1;
+
+    DASHER_TRACEOUTPUT("Fr %f Steps %d Samples %d Time2 %d rxmax %f\n", m_dFr, m_iSteps, m_iSamples, m_iTime2, m_dRXmax);
+  }
+}
+
+void CFrameRate::HandleEvent(Dasher::CEvent *pEvent) {
+
+  if(pEvent->m_iEventType == EV_PARAM_NOTIFY) {
+    Dasher::CParameterNotificationEvent * pEvt(static_cast < Dasher::CParameterNotificationEvent * >(pEvent));
+
+    switch (pEvt->m_iParameter) {
+    case LP_MAX_BITRATE: // Delibarate fallthrough
+    case LP_BOOSTFACTOR:
+      BitrateChanged(GetLongParameter(LP_MAX_BITRATE) * GetLongParameter(LP_BOOSTFACTOR) / 10000.0);
+      break;
+    case LP_FRAMERATE:
+      FramerateChanged(GetLongParameter(LP_FRAMERATE) / 100.0);
+    }
+  }
+}