Adding equalizer to the Symbian C++ audio player

Comments

Dear all!

Background: I have successfully built and installed the example application Image:PlayerExtrasExample.zip on my Nokia N95 device using the demo signing site from Symbian (symbiansigned.com)

Problem: However, when I try to extend the application, trying to create a new Preset for the equalizer I run into various truble:

The new equalizer preset itself is indeed created and I can see and choose it in the equalizer list from the N95 media player equalizer preset list. BUT the equalizer band settings I wished to store within this new presest is not stored at all. I.e only the default settings are contained within the new equalizer preset.

Can any hint me what I do wrong here?

The altered code is stated below:

TInt32 levelMin, levelMax;

// this exists ok on target if(iMdaAudioPlayerUtility) {

    if(iAudioEqualizerUtility == NULL)
    {
         iAudioEqualizerUtility = CAudioEqualizerUtility::NewL(*iMdaAudioPlayerUtility); // this exists ok on target
    }

    iBandNum = iAudioEqualizerUtility->Equalizer().NumberOfBands();           //this is printed in the device N95 and is correctly = 8
    iAudioEqualizerUtility->Equalizer().DbLevelLimits(levelMin, levelMax);    //these levels are retrieved and printed on device N95

    TInt nn = iAudioEqualizerUtility->NumberOfPreDefinedPresets();

    TBuf<50> buffer; 
    buffer = iAudioEqualizerUtility->GetPresetL(nn-1);
    iBuf = buffer;  // this preset is printed correctly on target N95 (= Rock)

    // used to create a dummy preset name to for testing purpose.      
    _LIT( KHello, "AABBCC" );
    TBuf<100> something;
    something.Copy(KHello);			

    // here I just try to set a value on the fourth equalizer band in order to try to verify if this value is really stored in the device
    // However, this new band value is NOT stored. Why not????

    iAudioEqualizerUtility->Equalizer().EnableL();
    iAudioEqualizerUtility->Equalizer().SetBandLevelL(4, 11);
    iAudioEqualizerUtility->Equalizer().ApplyL();

    //This new equalizer preset name shows upp after creation in the media 
    // player on the N95 device. But the band value I wanted to store did not show upp, why??		
    iAudioEqualizerUtility->CreatePresetL(something, iAudioEqualizerUtility->Equalizer());

}

Note: I apply all capabilities allowed using the demo signing at symbiansigning.com and have set the following capabilities in the .mmp file: ReadDeviceData ReadUserData SwEvent TrustedUI UserEnvironment WriteDeviceData WriteUserData

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Symbian has several audio enhancement APIs that can be used to modify the audio experience. One of them is the CAudioEqualizerUtility API. This snippet can be self-signed.

Article Metadata

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Code Example

Source file: Media:PlayerExtrasExample.zip

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Tested with

Devices(s): Nokia N95

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Compatibility

Platform(s): S60 3rd Edition

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Platform Security

Signing Required: Self-Signed

Capabilities: None

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Article

Keywords: CAudioEqualizerUtility, TEfAudioEqualizerUtilityPreset

Created: User:Technical writer 1 (09 Oct 2008)

Last edited: hamishwillee (03 Dec 2012)

Preconditions

The audio player must be fully constructed before constructing the instance of the API. This can be done with the following lines of code:

 iMdaAudioPlayerUtility = CMdaAudioPlayerUtility::NewFilePlayerL(aFileName,
                                          *this,
                                          EMdaPriorityNormal,
                                          EMdaPriorityPreferenceTimeAndQuality);

MMP file

The following capabilities and libraries are required:

CAPABILITY NONE
LIBRARY AudioEqualizerUtility.lib  
Header audioequalizerutility.h

Source file

First you need to construct the equalizer instance:

 iAudioEqualizerUtility = CAudioEqualizerUtility::NewL(*iMdaAudioPlayerUtility);

Use the following code to query equalizer presets:

 TArray<TEfAudioEqualizerUtilityPreset> allPresets = 
   iAudioEqualizerUtility->Presets();

Use the following code to apply an equalizer preset:

 iAudioEqualizerUtility->ApplyPresetL(preSetIndex);
 // where preSetIndex is 0 to (iAudioEqualizerUtility->Presets().Count() – 1)

Test application

File:PlayerExtrasExample.zip

See also

• Adding doppler effects to the audio player in Symbian C++
• Adding source location effects to the Symbian C++ audio player
• Adding listener's location effects to the Symbian C++ audio player
• Adding bass boost to the Symbian C++ audio player
• Adding stereo widening to the Symbian C++ audio player
• Adding reverb to the Symbian C++ audio player