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How to Set and Get the AMR Stream Property

A user has to first create an instance of the AMR payload formatter. Then, the user can set and get the AMR stream property.

The following table contains the configurable AMR stream properties and their default values.

AMR stream properties	Default values
Bit rate	0
Frame Quality	AMR quality is good (1)
Header Type	IF2 (2)
No of Frames	1
Mode	Octet Aligned Mode (1)
Band	Wide Band (1)
Change Mode Request	0

The following code shows the valid set of all AMR stream properties so that a user can accordingly get or set the values.

// AMRPROPERTY.H

enum TAmrNBBitRate
    {
    EAmr_4_75_Kbps = 0,
    EAmr_5_15_Kbps = 1,
    EAmr_5_90_Kbps = 2,
    EAmr_6_70_Kbps = 3,
    EAmr_7_40_Kbps = 4,
    EAmr_7_95_Kbps = 5,
    EAmr_10_2_Kbps = 6,
    EAmr_12_2_Kbps = 7,
    EAmr_SID_Nb_Kbps = 8,
    // Future rates will be added here 
    EAmr_No_Data_Nb   = 15
    };
    
enum TAmrWBBitRate
    {
    EAmr_6_60_Kbps  = 0,
    EAmr_8_85_Kbps  = 1,
    EAmr_12_65_Kbps = 2,
    EAmr_14_25_Kbps = 3,
    EAmr_15_85_Kbps = 4,
    EAmr_18_25_Kbps = 5,
    EAmr_19_85_Kbps = 6,
    EAmr_23_05_Kbps = 7,
    EAmr_23_85_Kbps = 8,
    EAmr_SID_Wb_Kbps= 9,
    // future rates will be added here
    EAmr_No_Data_Wb =15    
    };
    
enum TAmrFrameQuality
    {
    EBadQuality = 0,
    EGoodQuality = 1
    };
    
enum TAmrHeaderType
    {
    ERawMode = 0,
    EIF1Mode = 1,
    EIF2Mode = 2
    };
    
enum TAmrMode
    {
    EOctetAlignedMode = 1,
    EBandWidthOptimizedMode = 2
    };
    
enum TAmrBand
    {
    EWideBand = 1,
    ENarrowBand = 2
    };
    
//The Change Mode Request value depends on whether the AMR is narrow or wide band.
enum TAmrChangeModeRequest
    {
    EAmrChangeModeRequest_0 = 0,
    EAmrChangeModeRequest_1 = 1,
    EAmrChangeModeRequest_2 = 2,
    EAmrChangeModeRequest_3 = 3,
    EAmrChangeModeRequest_4 = 4,
    EAmrChangeModeRequest_5 = 5,
    EAmrChangeModeRequest_6 = 6,
    EAmrChangeModeRequest_7 = 7,
    EAmrChangeModeRequest_8 = 8,
    EAmrChangeModeRequest_9 = 9,
    // future modes will be added here
    EAmrChangeModeRequest_15 = 15
    };

How to set the AMR stream property

If a user wants to set the AMR stream properties then the user has to individually set the specific AMR stream properties and then call the CStreamFormatter::SetStreamProperty() API. This is done by using the respective functions for each property.

The following code shows how to set the AMR stream properties.

// Create an instance of AMR Payload Formatter by passing KAmrFormatterUid
CStreamFormatter * aStreamFormatter =  CStreamFormatter::NewL(TUid::Uid(KAmrFormatterUid));

// First set the individual AMR stream properties if the user wants to, otherwise default values are used
CStreamProperty* aStreamProperty = aStreamFormatter->ConfigFactory(); //

//Get the CAmrStreamProperty property reference from CStreamProperty base class
CAmrStreamProperty* aAmrStreamProperty = (CAmrStreamProperty*)aStreamProperty;

// Set the bit rate to BitMode
TInt8 ret1 = aAmrStreamProperty->SetAmrBitRate(BitMode);  // Default bit rate is 0

// Set the AMR frame quality to the value passed as input
aAmrStreamProperty->SetAmrFrameQuality(TAmrFrameQuality); // Default AMR quality is good (1)

// Set the no of frames to be packed in a single RTP packet
TInt8 ret2 = aAmrStreamProperty->SetAmrNoofFrames(NoofFrames); // Default value is 1

// Set the header type to the value passed as input
aAmrStreamProperty->SetAmrHeaderType(TAmrHeaderType); // Default header type is IF2 (2)

// Set the AMR mode to the value passed
aAmrStreamProperty->SetAmrMode(TAmrMode);  // Default mode is Octet Aligned Mode (1)

// Set the AMR band to the value passed as input
aAmrStreamProperty->SetAmrBand(TAmrBand); // Default Band is Wide Band (1)

// Set the Change Mode Request to the value passed as input
aAmrStreamProperty->SetAmrChangeModeRequest(TAmrChangeModeRequest); //Default mode request is set to 0

After the user sets the AMR properties the CStreamFormatter::SetStreamProperty API is called.

// Call the SetStreamProperty() function of the interface        
aStreamFormatter->SetStreamProperty(aStreamProperty);

How to get the AMR stream property

If a user wants to get the AMR stream properties then the application has to call CStreamFormatter::GetStreamProperty() API and then individually get the specific AMR stream properties. This is done by using the respective functions for each property.

The following code shows how to get the AMR stream properties.

// Create an instance of AMR Payload Formatter by passing KAmrFormatterUid
CStreamFormatter * aStreamFormatter =  CStreamFormatter::NewL(TUid::Uid(KAmrFormatterUid));

// Get the AMR stream properties
CStreamProperty* aGetStreamProperty = aStreamFormatter->GetStreamProperty();

//Get the CAmrStreamProperty property reference from CStreamProperty base class
CAmrStreamProperty* aAmrGetStreamProperty = (CAmrStreamProperty*)aGetStreamProperty;

// Get the AMR bit rate
TInt BitMode = aAmrGetStreamProperty->AmrBitRate();

// Get the AMR header type
TAmrHeaderType amrHeaderType = aAmrGetStreamProperty->AmrHeaderType();
        
// Get the no of frames packed in the current AMR session
TInt NoofFrames = aAmrGetStreamProperty->AmrNoofFrames();

// Get the current AMR mode
TAmrMode amrMode = aAmrGetStreamProperty->AmrMode();

// Get the current AMR band
TAmrBand amrBand = aAmrGetStreamProperty->AmrBand();

// Get the quality of AMR frame
TAmrFrameQuality amrFrameQuality = aAmrGetStreamProperty->AmrFrameQuality();

// Get the Change Mode Request
TAmrChangeModeRequest amrChangeModeRequest = aAmrGetStreamProperty->AmrChangeModeRequest();

Parent topic: AMR Payload Formatter