[LAU] USB device gives wrong data?

[william estrada]

Fons,

   Thanks for the response.

   What you suggested is what I did but I only use one 'silence byte'. That
is definable to match the 'silence byte' for different devices.  It seems
to work OK.

   Do you think that a range of 'silence bytes' would work better?


William Estrada
MrUmunhum at popdial.com
Mt-Umunhum-Wireless.net ( http://Mt-Umunhum-Wireless.net )
Ymessenger: MrUmunhum



Fons Adriaensen wrote:
> On Mon, Oct 22, 2007 at 10:17:50AM -0700, william estrada wrote:
> 
>>   Yes, the format is U8, it is a simple recording program to make '.wav'
>> files. The filtering does work when adjusting the 'silence byte'. It
>> appears that the device drivers are not consistent with this value?
>> So I will be adding an option to change the value of the 'silence byte'.
>>
>>   How do I use the RMS value to remove noise?  A URL that I could read?
> 
> It's probably not worth the effort for 8 bits. What you see is a simple
> DC offset. Probably the easy approach is to consider a range of values
> e.g. 0x7E...0x82 as silence. Any value outside the range starts the
> recording, until you find a long series of samples within the silence
> range.
> 
> So the algo would be:
> 
>   If you find a value in the silence range, increment a counter.
>   If the counter reaches a certain value, stop.
>   If you find a value outside the range, start and reset the
>   counter.
> 
> You could also use a counter to avoid too many false starts. 
> 
> Ciao
>