[Speex-dev] Porting Speex on C5509A and CELP Algorithm Documentation

Jean Quirion jquirion at orion.ns.ca
Fri Jul 20 10:57:55 PDT 2007



Thank you very much for your suggestions. I managed to get the C55x code
working on the simulator. I would like to port Speex both on a C5502 EVM and
a C5509A EVM. As such, if you can provide me with the details of your port
on the C5509A, it would be greatly appreciated. 


Furthermore, I am looking for some technical documentation on the CELP
algorithms. I would like to better understand the math being implemented. Do
you know where such documentation can be found?




Jean Quirion


From: Jim Crichton [mailto:jim.crichton at comcast.net] 
Sent: Thursday, July 19, 2007 10:54 AM
To: Quirion, Jean; speex-dev at xiph.org
Subject: Re: [Speex-dev] How Can I Get involved in Speex

There is a port for the TI C55X, in the TI directory of the source tree.
This builds and runs directly on the TI C55x simulator (Code Composer).  I
have run this on the Spectrum Digital C5509A EVMPLUS board, by modifying
some of the sample audio drivers (I could provide some details if you chose
that board).  You can certainly get started in the simulator.
The Speex port does not include any assembly optimization for TI, so that is
an area that you might be interested in.  If you are considering the Speex
echo canceller, that could greatly benefit from a TI-optimized FFT.  I have
not used the preprocessor myself.
You should plan on providing external memory for your DSP if you are doing
more than the basic codec.  Speex runs fairly efficiently in C on TI DSPs,
but it has a big footprint.
I hope this in helpful in getting started with the DSP target.  I will defer
to Jean-Marc on how to contribute to the project.
Jim Crichton

----- Original Message ----- 
From: Quirion,  <mailto:jquirion at orion.ns.ca> Jean 
To: speex-dev at xiph.org 
Sent: Thursday, July 19, 2007 8:04 AM
Subject: [Speex-dev] How Can I Get involved in Speex Fixed-PointDevelopment?


My name is Jean Quirion and I am a DSP engineer. Currently I am
working on a project where it is desired to implement a VoIP solution
over a GSM GPRS link. I would like to use Speex as the vocoder for
this application. This application would require the Speex
encoder/decoder and possibly the pre-processor to run on a low power
fixed-point DSP such as a TI C55x.

Thus, I am interested in getting involved in the fixed-point
implementation of Speex. I feel I can contribute significantly to the
Speex project while effectively developing a vocoder solution for my

Can you tell me how I can get started? I looked at the list of tasks
on the Seepx wiki and I find that the following would be best suited
for my interests:

Complete fixed-point (DSP development)
.       Rest of the narrowband modes
.       Preprocessor (noise suppression, AGC)
.       Jitter buffer

Please let me know how to move forward. Where does the Speex vocoder
fixed-point implementation stands? Has if been successfully ported and
tested onto a TI DSP evaluation board (i.e. an EVM)? If not, and if it
can be helpful, I would be interested in tackling that task.


Jean Quirion


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