concerns regarding voice calls

[constantijn]

Good day! I am planning to create a lie detector application for a symbian phone using Carbide c++. I don't know much about this programming language, and I am hoping someone could help me with the following:

1. Is there a way for me to record voice calls?
2. Is there a way for me to compute the sampling rate of the recorded
voice calls?

Any help with these two matters would be greatly appreciated.

Thank you very much.

[Nitin SuperByte]

Good day! I am planning to create a lie detector application for a symbian phone using Carbide c++. I don't know much about this programming language, and I am hoping someone could help me with the following:

1. Is there a way for me to record voice calls?
2. Is there a way for me to compute the sampling rate of the recorded
voice calls?

Any help with these two matters would be greatly appreciated.

Thank you very much.

see CMdaAudioRecorderUtility in SDK documentation for recording... and for caller's voice reffer
RMobilePhone RMobileLine RMobileCall RTelServer RLine RPhone RCall

[skumar_rao]

Good day! I am planning to create a lie detector application for a symbian phone using Carbide c++. I don't know much about this programming language, and I am hoping someone could help me with the following:

1. Is there a way for me to record voice calls?
2. Is there a way for me to compute the sampling rate of the recorded
voice calls?

Any help with these two matters would be greatly appreciated.

Thank you very much.

If you are using s60 v3.x then it is suggested that you look in to the APS {Audio Proxy server} APIs.

[nigel.brown]

I think the sampling rate is standard for GSM 8000 /s. I also think it may be variable in VOIP connections, so you may need more than one set of filters, however 8000 /s will be the norm for some time (basically because peoples voices aren't changing that much)

[constantijn]

Thank you very much. I have one more question. How do I determine the (1) number of samples and (2) segment length from the recorded voice calls?

[nigel.brown]

The number of samples is the time in seconds of the recorded data * 8000. Not sure what you mean by the segment length. I expect you will have to supply a buffer of a know size and process it when it is full.

If you are trying to pick up stress levels in the voice then you will have to compare the instantaneous frequency profile with a long term average. Exactly what instantaneous and long term mean is up to you and your app. Long term could be one call or over a number of calls if you store which user made the call. (but I suppose then you are assuming that the same user is always using the same phone)