amr recording in windows phone 7

Question

How can I record and AMR audio clip on windows phone?

Microphone gives only PCM samples and it need to be converted to AMR before writing to the file.

How this conversion can be done? If anybody having any sample code , pls share.

Answer 1

I don't think there are any libraries available for WP7 that do this. The .Net libraries that exist either use native code or a third-party library to perform the conversion.

So then your options are either to implement your own conversion library (sounds like a nice open-source project!), or to setup a web service that performs the conversion using existsing libraries.

To do the first option you would probably start with a library like OpenCode-arm and convert the code to C#. Sometimes such conversions are quite simple while other times they can be very complex. But most of the time it is possible to to the conversion if you have the time for it.

A quicker alternative would be to setup a web service where you upload the PCM data that returns AMR data. In this service you could use one of the existing libraries that are available for .Net and other platforms.

You don't say what you need the AMR file for. If you plan to send it somewhere then maybe you could send the PCM data and do the conversion server-side?

Edit:

If you opt to setup a web service, a simple shell of how it could work would be to setup a class that host the conversion method and implement a public method that does the conversion:

[ServiceContract]
public class ConvertService
{
  [OperationContract]
  public byte[] ConvertPcmToAmr(byte[] pcmData)
  {
     // Do the conversion here and return the data
  }
}