Hi Glen,
Thank you very much for your reply . I have few confusions. If I would use
8bit resolution per sample , then I would need to change line 3 in the
following piece of code , right ? If I would change line 3 to buf =
(char*)malloc(nsam*sizeof(char)) , will it work ? I mean do I need to
change anything inside of the codec ?
Line 1: codec2 = codec2_create(CODEC2_MODE_1300);
Line 2: nsam = codec2_samples_per_frame(codec2);
Line 3: buf = (short*)malloc(nsam*sizeof(short));
Line 4: nbit = codec2_bits_per_frame(codec2);
Line 5: bits = (unsigned char*)malloc(nbit*sizeof(char));
kind regards
Anomadarshi
On Sun, Jun 12, 2016 at 11:43 AM, glen english <[email protected]> wrote:
> 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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