[arm-allstar] Audio processing, was Re: cdm1250 transmit audio

[Patrick Perdue]

I'm definitely looking forward to any future audio processing support, 
especially if SoX is involved, since we could then use ladspa. I would 
especially like to process analog input to clean things up for digital 
bridges. I'm thinking downward expander plus gate, so the digital 
vocoders have less noise to process, especially with strong to moderate 
analog signals, EQ and limiter. This could also help with the ever 
present echo link 8-bit dithering. This is something I've wanted to do 
for a while. Having a moderate downward expander and EQ or light 
multi-band compression on my transmitted audio to Allstar would be nice 
as well. Just something subtle to keep levels and equalization in line 
between radios, but not to be obvious that there is processing.


On 3/1/2020 10:23 PM, "Doug Crompton via ARM-allstar" wrote:
> Jed,
>
>   Pre and de-emphasis are not meant to be used when they are applied to the
> audio to/from the transceiver. Using them to make things sound more or less
> bright when they have already been applied is not a good idea especially on
> audio going out to the network. Pre-emphasis increases the high end at a
> prescribed rate for audio FROM your node, what you hear. De-emphasis
> decreases high end on audio TO your node, what others hear.  Most of us are
> using radios that do this internally and leave these settings OFF. If you
> were using a radio that did not apply one or the other or both you would
> turn the appropriate one on. The bottom line is that they are not meant for
> casual audio equalization but rather for a defined method every FM signal
> uses.
>
> It is in our plans and sometime in the future you will be able to apply
> software equalization using an external program such as sox but for ow if
> you must change equalization your best bet is feeding the analog audio out
> of the FOB through a hardware equalizer.
>
>
> *73 Doug*
>
> *WA3DSP*
>
> *http://www.crompton.com/hamradio <http://www.crompton.com/hamradio>*
>
>
> On Sun, Mar 1, 2020 at 5:00 PM "Jed Barton via ARM-allstar" <
> arm-allstar at hamvoip.org> wrote:
>
>> Hey guys,
>>
>> So i'm trying to do some audio adjustment on my cdm1250 to make it
>> sound better.  I'm trying to figure out the pre-emphasis and
>> deemphasis on the radio.  I wanna add a little more high end to the
>> transmit audio.  Can i try this in simple USB, or where should i go?
>>
>> Cheers,
>>
>> Jed
>> _______________________________________________
>>
>> ARM-allstar mailing list
>> ARM-allstar at hamvoip.org
>> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>>
>> Visit the BBB and RPi2/3/4 web page - http://hamvoip.org
>>
> _______________________________________________
>
> ARM-allstar mailing list
> ARM-allstar at hamvoip.org
> http://lists.hamvoip.org/cgi-bin/mailman/listinfo/arm-allstar
>
> Visit the BBB and RPi2/3/4 web page - http://hamvoip.org