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Onestone's bit codec

Started by Micah November 10, 2004
Most of my very best ideas come in sleep or idle modes, especially when 
idling in the 'library'.

Al

Micah wrote:

> But it takes me so long to accomplish anything in
LPM3! 
> 
> -Micah
> 
> On Thursday 11 November 2004 03:38 pm, onestone wrote:
> 
>> Micah wrote:
>> > I was playing with a C version of adpcm modified from the Sun
>> > Microsystems 32kbit codec by Marc Randolph. It sounds like a
similar
>> > thing. It didn't immediately work though although I got it to
compile.
>> > Would you mind sharing? I'd love to take look. This sound
compression
>> > stuff is consuming me currently. :)
>>
>> Then use LPM3, for less current ;?}
>>
>> Al
>>
>> > -Micah
>> >
>> > On Wednesday 10 November 2004 11:14 pm, Jaromir Subcik wrote:
>> >> Hi,
>> >> some times ago I implemented 2bit ADPCM according to G.726
>> >> Recommendation into MSP running on 8MHz and it works wery
well. As a
>> >> source I used TI's BPRA053 where is implementation for TMS,
but encoder
>> >> is very well described and it fits into MSP - I programmed it
in
>> >> assembler. It is not bit codec, it works with 8k samples/sec
(I used
>> >> internal ADC for input and PWM for output, now you can use
MSP430F16x
>> >> with DAC) and final coded bitstream is 16kbit/s. It may better
suits
>> >> you.
>> >>
>> >> Jarda
>> >>   ----- Micah wrote: -----
>> >>   Hi,
>> >>
>> >>   after spending a couple hours playing with things, I think I
have a
>> >>pretty good understanding of the concept of the roman black
style
>> >>bit-codec. My question is, as I'm outputting via the DAC to an
audio
>> >>amplifier, (via a filter) the RC effect will not be available.
>> >>
>> >>   The obvious solution to me is to decode the bitstream into a
series
>> >> of DAC levels, and play them back at the same rate  as
encoding. As I'm
>> >> not a huge expert on analog circuits, I was wondering if
there's an
>> >> obvious error with this mode of thought? More processing,
that's for
>> >> sure, but is it workable?
>> >>
>> >>   I'll work on a decoding routine and post it here to see what
you
>> >> think.
>> >>
>> >>   Thanks,
>> >>   -Micah
>> >>
>> >>
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Beginning Microcontrollers with the MSP430