[Asterisk-Users] Adpcm, 6KHz codec

[Steve Underwood]

Alex Zarubin wrote:

> I am positive, 4 bits per sample, 6000 Hz.
>
> This is a default play/record setting for the older Dialogic R4 API 
> and we need
> to play zillions (sic!) of files (messages) recorded this way.
>
> Conversion issues:
>         - expensive
>
C versions of the OKI/Dialogic ADPCM codec are freely available.

>         - resampling quality
>
It does need resampling, as the codec will give you linear PCM at 
6000/s. The Dialogic cards have to do that anyway, to make an 8000/s 
stream for an A-law or u-law PCM channel. You won't loose more quality 
than they do (unless you do something dumb).

>         - storage
>         - application changes
>         - etc.
>
> Would be real nice and useful to have this codec.
>
> Thank you.
>
> Alex Zarubin
> Webley Systems, Inc.
>

Regards,
Steve