[Speex-dev] ADC 12bit

[Seifeddine Jlassi]

Hello evereybody;
 
I am very confused and i hope that someone could help me.
In fact i'm using an ADC 12bit to sample voice and then i encode the data using Speex.
The problem is when i try to decode and replay the voice samples i got much noise. I think that the pb is iabout the conversion from 12bit unsigned to 16bit signed format which is required by speex codec.
 
i have used the following code:
signed_vakue16 = (unsigned_value12<<4)^0x8000;
 
also i have tryed to convert the 12bit into 8bit and then transformat it into 16bit signed format:
signed_vakue16 = ((unsigned_value12>>4)<<8)^0x8000;
 
could anyone please give me more clarifiations, thanks
 
best regards to all
Seif
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