Anomadarshi,

simply implement a 1:2 upsampler and 2:1 downsampler

this will provide your required functionality.

Sampling a speech signal at only 4kHz, that is a nyquist freq of 2kHz, likely leading to  a audio input bandwidth of perhaps 1.7kHz will provide very very poor quality speech. A minimum of 2.4kHz audio bandwidth is suggestion.

The use of 16 bits would seem to be a waste of time.

I would suggest changing your hardware to 8kHz sample rate and 8 bits. Or even 6 bits.
Use of an AGC ahead of codec2 might improve results.

regards

glen english
vk1xx




On 12/06/2016 7:08 PM, Anomadarshi Barua Shuvro wrote:
Hi,
I have been using this codec for transmission of voice over wireless network. Because of my hardware constraint , I am sampling the voice with 4KHz with 16 bit resolution . After compression at the transmitter side and decompression at the receiver side the voice quality is very poor. I saw that the codec is written for 8KHz sampling rate .
 Will it be possible to use it for 4kHz sampling rate with good voice quality and if yes how ?

kind regards
Anomadarshi


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consuming the most bandwidth. Provides multi-vendor support for NetFlow, 
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