Encode driver reconfiguration

As an evolution of the audio transcoder server, it would be nice to be able to change the encoding parameters from the configuration file, dynamically, without restarting the server. So the encode section of the configuration must evolve to contain the following information:

"encode": {
  "samplerate": 16000,
  "bitdepth": 16
},

The two samplerate and bitdepth parameters for now are hardcoded in the encoder driver. Two steps are necessary to take these settings into account dynamically:

1. Add these settings in the configuration file and use them in the encode driver
2. Monitor the configuration file, reparse it, and use the new settings

With these changes, the reactivity diagram of the application becomes as follows:

Figure 8.7: Reactivity diagram of the transcode server with dynamic configuration

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