Speex dev - Dec 2006 - Integrating speex with VideoNet application: Constantbackground noise

Hi Jean-Marc,

Thanks. I've got the code for sampleenc and sampledec. But I didn't know
how to verify whether the decoded file is correct.
So I tried to analyse the decoded output and compile with my input.

Test case: PCM samples, 8 bit, 8000 samples per sec. 
When I pulled all my input to 0s, after encode and decode, the output fluctuates
around -0.12 to 0.2 (in float), so when finally cast to character, they are
still 0. Hence I've hear no background sound at all. =>

When I set all my input values to 127 (max +ve value) and -128 (max -ve value),
I heard a soft background noise. But still acceptable.

When I use my actual input, the pounding background noise came back.
1. My input fluctuates around -128 and 127. 
2. The decoded output is highly random. Initially it has values close to 0, then
slowly the value danced around in a wide range of -163 to 201.

When I commented out the encode and decode, I am able to hear the recorded sound
without no background noise.

Is my decoded output expected? Since I'm dealing with a 8 bit sample, am I
right to say that I will not have the "big/little endian" issue?

What has gone wrong???


Regards,
Carine


----- Original Message ----
From: Jean-Marc Valin <jean-marc.valin@usherbrooke.ca>
To: Carine Liang <carineliang@yahoo.com.sg>
Cc: John Miles <jmiles@pop.net>; speex-dev@xiph.org
Sent: Monday, 25 December 2006 10:22:44 AM
Subject: Re: [Speex-dev] Integrating speex with VideoNet application:
Constantbackground noise

Have you tried starting with sampleenc/sampledec instead of doing
everything from scratch. That and the manual should contain everything
that's needed.

    Jean-Marc

Carine Liang a ?crit :
> Hi,
> 
> 
> 
> I'm still unable to get rid of the background noise though I've
> changed the PCM samples to 16 bit. I'm began to wonder if I can just
> take the PCM samples and encode them.
> 
> What my application tries to do is to record the voice from a
> microphone, encode it, send it via the socket to a peer, decode at
> the peer's side and play the voice. My application works fine without
> the codec but I need to achieve a lower data rate. Anyone has done
> that before?
> 
> Is there anyone who's deal with encoding and decoding PCM samples in
> windows?
> 
> Please help.
> 
> Carine
> 
> ----- Original Message ---- From: John Miles <jmiles@pop.net> To:
> Carine Liang <carineliang@yahoo.com.sg>; speex-dev@xiph.org Sent:
> Friday, 3 November 2006 12:32:43 AM Subject: RE: [Speex-dev]
> Integrating speex with VideoNet application: Constantbackground noise
> 
> 
> 
> 
> 
> DIV { MARGIN:0px;}
> 
> 
> 
> Yes, it's necessary; Speex will encode signed 16-bit PCM data and
> decode to the same format.  See the examples that come with it.
> 
> 
> 
> 8-bit audio is not something you would ever want to use.
> 
> 
> 
> 
> 
> ------------------------------------------------------------------------
> 
> 
> _______________________________________________ Speex-dev mailing
> list Speex-dev@xiph.org 
> http://lists.xiph.org/mailman/listinfo/speex-dev





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> Thanks. I've got the code for sampleenc and sampledec. But I didn't
> know how to verify whether the decoded file is correct. So I tried to
> analyse the decoded output and compile with my input.
How about actually listening to the output first?
> Test case: PCM samples, 8 bit, 8000 samples per sec. When I pulled
Where in the manual does it say that 8-bit PCM is a valid input?

[...]
> Is my decoded output expected? 
Yes. Based on the "garbage in, garbage out" principle.
> Since I'm dealing with a 8 bit sample,
> am I right to say that I will not have the "big/little endian"
issue?
No, just the "not the right type in the first place" issue.
> What has gone wrong???
Euh, maybe not paying enough attention to the manual and the sample code?

	Jean-Marc
> 
> Regards, Carine
> 
> 
> ----- Original Message ---- From: Jean-Marc Valin
> <jean-marc.valin@usherbrooke.ca> To: Carine Liang
> <carineliang@yahoo.com.sg> Cc: John Miles <jmiles@pop.net>;
> speex-dev@xiph.org Sent: Monday, 25 December 2006 10:22:44 AM 
> Subject: Re: [Speex-dev] Integrating speex with VideoNet application:
> Constantbackground noise
> 
> Have you tried starting with sampleenc/sampledec instead of doing 
> everything from scratch. That and the manual should contain
> everything that's needed.
> 
> Jean-Marc
> 
> Carine Liang a ?crit :
>> Hi,
>> 
>> 
>> 
>> I'm still unable to get rid of the background noise though I've
>> changed the PCM samples to 16 bit. I'm began to wonder if I can
>> just take the PCM samples and encode them.
>> 
>> What my application tries to do is to record the voice from a 
>> microphone, encode it, send it via the socket to a peer, decode at 
>> the peer's side and play the voice. My application works fine
>> without the codec but I need to achieve a lower data rate. Anyone
>> has done that before?
>> 
>> Is there anyone who's deal with encoding and decoding PCM samples
>> in windows?
>> 
>> Please help.
>> 
>> Carine
>> 
>> ----- Original Message ---- From: John Miles <jmiles@pop.net> To:
>> Carine Liang <carineliang@yahoo.com.sg>; speex-dev@xiph.org Sent:
>> Friday, 3 November 2006 12:32:43 AM Subject: RE: [Speex-dev] 
>> Integrating speex with VideoNet application: Constantbackground
>> noise
>> 
>> 
>> 
>> 
>> 
>> DIV { MARGIN:0px;}
>> 
>> 
>> 
>> Yes, it's necessary; Speex will encode signed 16-bit PCM data and 
>> decode to the same format.  See the examples that come with it.
>> 
>> 
>> 
>> 8-bit audio is not something you would ever want to use.
>> 
>> 
>> 
>> 
>> 
>>
------------------------------------------------------------------------
>> 
>> 
>> 
>> _______________________________________________ Speex-dev mailing 
>> list Speex-dev@xiph.org 
>> http://lists.xiph.org/mailman/listinfo/speex-dev
> 
> 
> 
> 
> 
> 
> Send instant messages to your online friends
> http://asia.messenger.yahoo.com