After initializing the Universal Speech Access API, applications use USAI functions to request text-to-speech (TTS) synthesizer resources from a speech server. Each synthesizer resource is associated with a specific NaturalAccess context.
Applications invoke saiCreateSynthesizer to allocate synthesizer resources. When using saiCreateSynthesizer, the application must specify the following:
NaturalAccess context handle.
Incoming Fusion RTP endpoint information, including the IP address and the port number to listen on.
(Optional) Name of a speech server where synthesizer requests are directed. If no speech server is specified, USAI defaults to the first server defined in the saiconfig.xml file.
(Optional) Client object identifier that USAI associates with any events returned for the synthesizer resource.
Pointer to a synthesizer handle container to receive the created synthesizer handle.
saiCreateSynthesizer is an asynchronous function. When saiCreateSynthesizer executes successfully, indicating that all specified parameters are valid, USAI sends a setup command to the speech server requesting a new synthesizer resource according to the specified parameters. USAI returns a synthesizer handle (synthHd) that the application references in subsequent requests for that resource. However, the application must wait for USAI to return SAIEVN_ENGINE_READY for the specified synthesizer before making any requests with the returned synthHd.
Note: After an application invokes saiCreateSynthesizer, the only command that USAI can execute before receiving SAIEVN_ENGINE_READY is saiReleaseSynthesizer.
The following illustration shows NaturalAccess and USAI interaction when creating synthesizer resources:
The following example shows how an application creates a USAI synthesizer resource:
DWORD rc = SUCCESS;
CTAQUEUEHD queueHd;
CTAHD contextHd;
SAI_SYNTHESIZER_HANDLE synthHd;
CTA_SERVICE_NAME cta_srvc_name;
CTA_INIT_PARMS cta_init_parms;
CTA_SERVICE_DESC cta_srvc_desc;
SAI_URL g_server = "SpeechServer";
SAI_RTP_ENDPOINT rtpEndpoint;
CTA_EVENT *event;
DWORD serverPortTts = 0;
// Initializing Natural Access environment
ctaInitialize(cta_srvc_name, cta_init_parm);
ctaCreateQueue(NULL, 0, queueHd);
ctaCreateContext(queueHd, 0, NULL, contextHd);
ctaOpenServices(contextHd, cta_srvc_desc, 1);
rtpEndPoint.Port = 2000;
rtpEndPoint.ipAddress = "10.10.1.1";
rc = saiCreateSynthesizer(contextHd, rtpEndpoint, g_server, 0, synthHd );
if ( rc == SUCCESS )
{
// Wait for SAIEVN_ENGINE_READY or SAIEVN_ENGINE_FAIL
rc = ctaWaitEvent( queueHd, event, 0 );
if ( (rc == SUCCESS) && (event == SAIEVN_ENGINE_READY))
{
SAI_EVENT_ENGINE_READY* serverPort = (SAI_EVENT_ENGINE_READY*) (event->buffer );
printf("Engine created successfuly, Port # :%d\n", serverPortàenginePort);
}
else if((rc == SUCCESS) && (event == SAIEVN_ENGINE_FAIL))
{
printf("Engine creation failed, engine not ready.\n");
}
}
else
{
printf("saiCreateSynthesizer failed.\n");
}