I am trying to understand what a codec actually is
In hardware, audio codec refers to a single device that encodes analog audio as digital signals and decodes digital back into analog. In other words, it contains both an analog-to-digital converter (ADC) and digital-to-analog converter (DAC) running off the same clock. This is used in sound cards that support both audio in and out, for instance.
So this implies codec is something that comes with both ADC and DAC converters (so a codec should have an analog input with a corresponding digital output and a digital input with a corresponding analog output)
From my limited understanding, codec should have some kind of coder and a decoder, that is, for whatever digital representation I get from a particular analog input, the codec should should give me a different, encoded version of this digital representation, and it should also be able to reverse this encoding (since it's a codec, unless I got it wrong and the digital equivalent itself is considered a type of encoding?)
However, this doesn't seem to make sense to me in terms of the DSP that I am working with
The following figure is from the datasheet of the CSR8670 Bluetooth Audio chip
In a lot of a places, the datasheet, other documents and comments in the sample programs mention the audio input ADC as a codec, so I assumed codec here meant the wikipedia definition
Looking at this picture, we can see that it shows ADC and digital codec to be two separate entities. Moreover, both the inputs from the analog mics as well digital mics go through the digital codec
What exactly does this mean? I can use the debugger to check the DSP memory for the numerical representation of whatever audio that comes in through the microphone. Does this imply that the numerical representation that I see in the DSP memory is not the same as what was generated by the ADC?
What is codec here, in very simple terms?