CPAudioCodecConfiguration

Objective-C

@interface CPAudioCodecConfiguration : NSObject

Swift

class CPAudioCodecConfiguration : NSObject

OpusConfiguration class contains all configuration of Opus audio codec. Configurations can be set using this class instance.

Since

1.0.0

  • Maxaveragebitrate specifies the maximum average receive bitrate of a session in bits per second (bit/s). The actual value of the bitrate can vary, as it is dependent on the characteristics of the media in a packet. Note that the maximum average bitrate MAY be modified dynamically during a session. Any positive integer is allowed, but values outside the range 6000 to 510000 SHOULD be ignored. If no value is specified, the maximum value will equals to corresponding mode of Opus and corresponding maxplaybackrate is the default. Decreasing MaxAverageBitRate will cause less bandwidth usage (For further information check RFC-7587).

    Important

    MobileSDK default maxAverageBitRate=20000

    6000 <= MaxAverageBitRate <= 510000

    In case this value set as -1 WebRTC defaults will be use.

    Since

    1.0.0

    Declaration

    Objective-C

    @property (nonatomic) NSInteger opusMaxAverageBitRate;

    Swift

    var opusMaxAverageBitRate: Int { get set }

    Return Value

    NSInteger

  • Ptime is the preferred duration of media represented by a packet that a decoder wants to receive, in milliseconds rounded up to the next full integer value. For Opus, possible values are 3, 5, 10, 20, 40, 60, or an arbitrary multiple of frame size rounded up to the next full integer value, up to a maximum value of 120. If no value is specified, the default is 20. Changing ptime effects all audio codecs. Increasing Ptime will cause less bandwidth usage (For further information check RFC-7587).

    Important

    MobileSDK default ptime=60

    3 <= MaxAverageBitRate <= 120 and it should be multiple of an Opus frame size rounded up to the next full integer value

    In case this value set as -1 WebRTC defaults will be use.

    Since

    1.0.0

    Declaration

    Objective-C

    @property (nonatomic) NSInteger ptime;

    Swift

    var ptime: Int { get set }

    Return Value

    NSInteger

  • Sets DTX value which will enable or disable Discontinuous Transmission feature of Opus codec. When using continuous transmission, Variable Bitrate will reduce the bitrate when the characteristics of the input signal permit, but it will never interrupt the transmission to the receiver. Therefore, the received signal will maintain the same high level of audio quality over the full duration of a transmission while minimizing the average bitrate over time. In cases where the bitrate of Opus needs to be reduced even further or in cases where only constant bitrate is available, the Opus encoder can use Discontinuous Transmission (DTX), where parts of the encoded signal that correspond to periods of silence in the input speech or audio signal are not transmitted to the receiver. A receiver can distinguish between DTX and packet loss by looking for gaps in the sequence number. On default DTX is disabled and enabling DTX will cause less bandwidth usage (For further information check RFC-7587). If application set dtxEnable parameter as ‘YES’ DTX will be enable, if application set it as ‘NO’ DTX will be disable.

    Important

    MobileSDK default DTX is enabled

    Since

    1.0.0

    Declaration

    Objective-C

    @property (nonatomic) BOOL opusDtx;

    Swift

    var opusDtx: Bool { get set }

    Return Value

    Boolean

  • Sets FEC value which will enable or disable ForwardErrorCorrection feature of Opus codec. The voice mode of Opus allows for embedding in-band Forward Error Correction (FEC) data into the Opus bitstream. This FEC scheme adds redundant information about the previous packet (N-1) to the current output packet N. On the receiving side, the decoder can take advantage of this additional information when it loses a packet and the next packet is available. Disabling FEC cause cause less bandwidth usage (For further information check RFC-7587). If application set fecEnable parameter as ‘YES’ FEC will be enable, if application set it as ‘NO’ FEC will be disable.

    Important

    MobileSDK default FEC is enabled

    Since

    1.0.0

    Declaration

    Objective-C

    @property (nonatomic) BOOL opusFec;

    Swift

    var opusFec: Bool { get set }

    Return Value

    Boolean

  • Sets the MaxPlaybackRate. Maxplaybackrate is a hint about the maximum output sampling rate that the receiver is capable of rendering in Hz. The decoder MUST be capable of decoding any audio bandwidth, but, due to hardware limitations, only signals up to the specified sampling rate can be played back. Sending signals with higher audio bandwidth results in higher than necessary network usage and encoding complexity, so an encoder SHOULD NOT encode frequencies above the audio bandwidth specified by maxplaybackrate. This parameter can take any value between 8000 and 48000, although commonly the value will match one of the Opus bandwidths . By default, the receiver is assumed to have no limitations, i.e., 48000. Decreasing MaxPlaybackRate will cause less bandwidth usage. Decreasing MaxPlaybackRate will cause less bandwidth usage (For further information check RFC-7587).

    Important

    MobileSDK default MaxPlaybackRate=16000

    8000 <= maxPlaybackRate <= 48000

    In case this value set as -1 WebRTC defaults will be use.

    Since

    1.0.0

    Declaration

    Objective-C

    @property (nonatomic) NSInteger opusMaxPlaybackRate;

    Swift

    var opusMaxPlaybackRate: Int { get set }

    Return Value

    NSInteger

  • Init CPAudioCodecConfiguration with MobileSDK preferred sets. If an application use this configuration MobileSDK will modify the Audio Codec parameters automatically with it’s preferred set.

    Since

    1.0.0

    Declaration

    Objective-C

    + (nonnull CPAudioCodecConfiguration *)configurationWithMobileSDKPreferredSet;

    Swift

    class func withMobileSDKPreferredSet() -> CPAudioCodecConfiguration

    Return Value

    Instance

  • Init CPAudioCodecConfiguration with WebRTC default sets. If an application use this configuration MobileSDK will not modify the Audio Codec parameters automatically.

    Since

    1.0.0

    Declaration

    Objective-C

    + (nonnull CPAudioCodecConfiguration *)configurationWithWebRTCDefaultSet;

    Swift

    class func withWebRTCDefaultSet() -> CPAudioCodecConfiguration

    Return Value

    Instance

  • This method will return the opus fmtp line parameters which will be in the fmtp line of SDP. Only Utils in WebRTC should call this method. Using this method Utils will modify the SDP and bitrate will decrease.

    Since

    1.0.0

    Declaration

    Objective-C

    - (nonnull NSString *)getOpusFMtpLine;

    Swift

    func getOpusFMtpLine() -> String

    Return Value

    String fmtpLine