The VoipMediaEngine class is the primary class for accessing all the
capabilities of the LanScape VOIP Media Engine.
The VoipMediaEngine..::.DtmfDecoder type exposes the following members.
Constructors
| Name | Description | |
|---|---|---|
 | VoipMediaEngine..::.DtmfDecoder | Initializes a new instance of the VoipMediaEngine..::.DtmfDecoder class |
Methods
| Name | Description | |||
|---|---|---|---|---|
| CreateDtmfDecoder |
The CreateDtmfDecoder API procedure is used to create a real time DTMF decoder. Using the created DTMF
decoder, your VOIP applications will be able to detect in-band DTMF tones from any audio media
stream. Application software generally uses this functionality to monitor specific audio media streams
of interest. When the application receives audio data blocks, it writes the audio data block to the
DTMF decoder. If there is DTMF content in the media stream sent to the decoder, the application will
be notified of the detected DTMF tone via a user supplied callback. Both DTMF "ON" and "OFF" transitions
are detected and sent to the application.
Before your application terminates, you must call the DestroyDtmfDecoder()()() API procedure to destroy the decoder and to regain its resources. | ||
| DestroyDtmfDecoder |
The DestroyDtmfDecoder API procedure is used to destroy a previously created DTMF decoder and reclaim all
resources associated with the decoder.
| ||
| DtmfDecoderGetMinimumDigitOnTime |
The DtmfDecoderGetMinimumDigitOnTime API procedure allows an application to retrieve the current
minimum digit ON time for the DTMF decoder.
| ||
| DtmfDecoderGetSignalThreshold |
The DtmfDecoderGetSignalThreshold API procedure allows the application to retrieve the current DTMF
detection threshold.
| ||
| DtmfDecoderGetTwist |
The DtmfDecoderGetTwist API procedure allows the application to retrieve the current allowed forward
and reverse twist of the DTMF input signal.
| ||
| DtmfDecoderSetMinimumDigitOnTime |
The DtmfDecoderSetMinimumDigitOnTime API procedure can be called by application software to specify
the minimum digit ON time for a detected DTMF digit.
Minimum digit ON time is generally set to 40Ms in order to comply with standard in-band DTMF requirements. However, for noisy DTMF signals, specifying a larger DTMF ON time improves noise immunity, improves "talk off" performance and reduces false DTMF digit detections (false positives). | ||
| DtmfDecoderSetSignalThreshold |
The DtmfDecoderSetSignalThreshold API procedure can be called to specify the DTMF signal detection
threshold. DTMF will only be detected by the DTMF decoder if the incoming DTMF signal power is greater
than the power threshold as set by this API procedure. For most application deployments, the default
signal threshold for the DTMF decoder should be adequate and you should not have to call this API procedure.
| ||
| DtmfDecoderSetTwist |
The DtmfDecoderSetTwist API procedure allows the application to specify the range of acceptable forward and
reverse twist of the DTMF input signal.
| ||
| DtmfDecoderWrite |
The DtmfDecoderWrite API procedure is used to pass audio sample blocks to a DTMF decoder. The audio
sample block must be PCM or uLaw data and consist of 20Ms worth of data (160 samples) at 8000Hz. To see
how to create a DTMF decoder that will be used for PCM or uLaw data blocks, see the UsePcm parameter
of the CreateDtmfDecoder(VoipMediaEngine, Boolean, Int32, Int32, Int32, Boolean, VoipMediaEngine..::.DTMF_DECODER_CALLBACK_PROC, Object) API procedure.
| ||
 | Finalize |
The Object's finalizer.
(Overrides Object..::.Finalize()()().) | ||
| SetDtmfTuningTables |
The SetDtmfTuningTables API procedure is used to change tuning parameters of DTMF decoders. Application software should
not call this API procedure unless otherwise instructed by LanScape support personnel.
|
Note:Fields
| Name | Description | |
|---|---|---|
 | FilterBlockN |
An internal filter tuning parameter.
Do not modify this value directly.
|
| hDtmfDecoderHandle |
The actual media enigne DTMF decoder native handle.
Do not modify this value directly.
|
| ImmediateEvaluation |
true if the DTMF decoder has been created to oerform immediate evaluation
Do not modify this value directly.
|
| MediaEngine |
The media enigne instance.
Do not modify this value directly.
|
| pManagedDtmfDecoderInstance |
A pseudo pointer to this managed wrapper.
Do not modify this value directly.
|
| pUserDtmfDecoderProc_Mananged |
An internal callback procedure.
Do not modify this value directly.
|
| SampleRate |
The sample rate.
Do not modify this value directly.
|
| UsePcm |
true if the DTMF decoder has been created to accept PCM samples.
false if the DTMF decoder has been created to accept uLaw samples.
Do not modify this value directly.
|
| UserDefinedData_Mananged |
Instance data passed to an internal callback procedure.
Do not modify this value directly.
|
| UserSamplesPerInputBlock |
The number of samples per input sample block.
Do not modify this value directly.
|
See Also
