[Speex-dev] Obtaining loudness information in 1.2beta2

Mihai Balea mihai at hates.ms
Thu Oct 25 17:09:04 PDT 2007

What would be a good parameter to return that would better represent  
the loudness of the signal?
As for the your other comments, I'll make the necessary changes and  


On Oct 25, 2007, at 7:45 PM, Jean-Marc Valin wrote:

> I'm in favor of the idea, but not of the current implementation. There
> are two problems:
> 1) The st->loudness parameter doesn't represent the amplitude of the
> signal, but the amplitude^5 (fifth power). That makes it hard to use
> 2) The call returns a float, but it should really be an int
> (spx_int32_t) so that it can work easily with fixed-point code
> There's a last minor thing: instead of  
> should be called SPEEX_PREPROCESS_GET_AGC_LOUDNESS. If you can send  
> me a
> patch that addresses these issues, I'll gladly apply it.
> 	Jean-Marc
> Mihai Balea wrote:
>> Hi all,
>> I'm working on a project called iaxclient
>> (http://sourceforge.net/projects/iaxclient).
>> We use speex for the majority of our audio processing, including  
>> voice
>> compression and processing.
>> One of the features of iaxclient is Analog AGC, which drives the
>> hardware mixer levels based on signal loudness.  Up until  
>> 1.2beta1, we
>> were able to access the internals of the SpeexPreprocessState  
>> structure
>> to get loudness information, but, of course, that is no longer  
>> possible
>> with 1.2beta2.  I would like to propose an addition to the  
>> preprocessor
>> control interface that exposes that parameter.  I'm attaching a patch
>> that contains the proposed change.
>> I'm looking forward to any comments and suggestions.
>> Cheers,
>> Mihai
>> --------------------------------------------------------------------- 
>> ---
>> _______________________________________________
>> Speex-dev mailing list
>> Speex-dev at xiph.org
>> http://lists.xiph.org/mailman/listinfo/speex-dev

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