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Telephone Grade Speech Compression?

picguy
Associate II
Posted on July 29, 2008 at 22:39

Telephone Grade Speech Compression?

2 REPLIES 2
picguy
Associate II
Posted on May 17, 2011 at 12:40

We have this:

8-bit ADC at 8KHz. 64-byte voice packets every 8 mSec. No compression. This comes to 64K bits per second.

We are looking for something better but it still has to sound like a telephone. Which unless I am mistaken means bandwidth limitation of 300 to 3,300 Hz.

So in our case better means data transmission bandwidth reduction.

We are flexible in that we can collect and play voice data faster than 8KHz if that would help. We can also collect and play using 12 bits of voice data if that would help. We are also flexible in the number of milliseconds in each packet. 10 to 15 mSec is quite okay. Each packet should standalone. I.e. a lost or mangled packet must have no effect on subsequent voice output.

We are using Performance Line parts at 72MHz. Although we are willing to use an external codec we likely have processing power enough to perform two simultaneous encodes along with two simultaneous decodes.

Does anyone know of such a codec? Ditto a URL or three with info.

16-32micros
Associate III
Posted on May 17, 2011 at 12:40

Hi Picguy,

Nice to see you consider our STM32 :-), This sounds like Speex codec,

isn't it ? You can visit

http://www.speex.org/

. Let me know if it the case or give me more details that I can discuss with my teammates software team within ST what we can provide you.

Cheers,

STOne-32. 😉