}
//---------------------------------------------------------------------------
-// wxAMMediaBackend::GetVolume
+// wxAMMediaBackend::GetVolume and SetVolume()
//
-// Gets the volume through the IActiveMovie interface -
-// value ranges from 0 (MAX volume) to -10000 (minimum volume).
-// -100 per decibel (Logorithmic in 0.01db per step).
+// Notice that for the IActiveMovie interface value ranges from 0 (MAX volume)
+// to -10000 (minimum volume) and the scale is logarithmic in 0.01db per step.
//---------------------------------------------------------------------------
+
double wxAMMediaBackend::GetVolume()
{
long lVolume;
return 0.0;
}
- // Volume conversion from Greg Hazel
- double dVolume = (double)lVolume / 125;
+ double dVolume = lVolume / 2000.; // volume is now in [-5..0] range
+ dVolume = pow(10.0, dVolume); // [10^-5, 1]
+ dVolume -= 0.00001; // [0, 1-10^-5]
+ dVolume /= 1 - 0.00001; // [0, 1]
- // convert to 0 to 1
- dVolume = pow(10.0, dVolume/20.0);
- // handle -INF
- dVolume *= 1 + pow(10.0, -5.0);
- dVolume -= pow(10.0, -5.0);
return dVolume;
}
-//---------------------------------------------------------------------------
-// wxAMMediaBackend::SetVolume
-//
-// Sets the volume through the IActiveMovie interface -
-// value ranges from 0 (MAX volume) to -10000 (minimum volume).
-// -100 per decibel (Logorithmic in 0.01db per step).
-//---------------------------------------------------------------------------
bool wxAMMediaBackend::SetVolume(double dVolume)
{
- // Volume conversion from Greg Hazel
- long lVolume;
- // handle -INF
- dVolume *= 1 - pow(10.0, -5.0);
- dVolume += pow(10.0, -5.0);
- // convert to -100db to 0db
- dVolume = 20 * log10(dVolume);
- // scale to -10000 to 0
- lVolume = (long)(125 * dVolume);
-
- HRESULT hr = GetAM()->put_Volume( lVolume );
+ // inverse the transformation above
+ long lVolume = static_cast<long>(2000*log10(dVolume + (1 - dVolume)*0.00001));
+
+ HRESULT hr = GetAM()->put_Volume(lVolume);
if(FAILED(hr))
{
wxAMLOG(hr);