Propeller Internet Walkie Talkie

Franz Achatz

i think i have some kind of a "blackout"·now.
Maybe its just a stupid idea but is it possible building an Internet Walkie Talkie or an Internet-Speaker???
We have a propeller MIC and Audio Out and a running/working ENC28J60 Ethernet Chip.
Maybe just telefon quality will do it (up to 4khz).
I have received samples of the Dallas DS80C400 and they can do it !!!!!!!!
If Dallas can do it i think the Propeller can do it as well.

have fun
Franz


·

deSilva

I never tried it... The problem is the "Quality of Service", HTTP is extremely "asynchronious", so you have to develop buffer strategies to re-assemble the pieces of sound sent. The bandwidth will be o.k. Most people can upload with 256 kBit/s..@ DSL

Drone

To do this Internet "Walkie Talkie" thing properly you're basically talking about building a Voice over IP (VoIP) gateway. I believe state of the art would require a lot of software pieces... The Internet protocol would be IP/UDP/RTP and it would be best to add RTP header compression as well. Then the voice codec would be G.829, but that requires a license, so a next best option might be the GSM codec. To establish and supervise the connection you would employ the ubiquitous SIP or H.263 layer - or better yet IAX which was designed to traverse NAT/PAT from the start. There are ASICs out there that do a lot of this stand-alone; I seem to remember seeing a company in Taiwan that did a VoIP chip that supported IAX and a bevy of codecs, but the name (Reddfox or some-such) escapes me at the moment.

David

Harrison.

It all depends on the complexity you wish to achieve. If all you want is something like an audio stream player, then it shouldn't be too hard. If you want the Propeller to encode and decode an audio stream then it will take a lot of work. The issues you would encounter would be out of order packets, QoS, compression, etc. All of these issues are evident in the complexity of modern VoIP devices and QoS routing.

I would suggest starting out easy, such as using a dedicated mp3 decoder chip (STA013 or VS1011). The Propeller could connect to an online audio stream (usually mp3 streams) and feed that stream directly to the mp3 decoder chip. The Propeller would not be doing much, other than minor buffering and tcp connection handling.

Harrison

deSilva

I think this is still to complex. I suggest the most simple WAV compression, piggi-backing this on simple HTTP and try to re.assemble things at the target The last thing however my need more memory space than the Prop has

Drone

Have a look at this link:

www.atcom.cn

I have a few of their AG-168V boxes. I think they cost something like $30 USD each. You just plug a phone into each box and make program them to address each other over the Internet. The nice thing about these boxes is that they come with the 8 kbps G829 codec, compressed RTP, and they do IAX, which traverses NAT/PAT by design and is fully compatible with the Asterisk free and open soft-switch (www.asterisk.org/). (You do NOT need a softswitch to act as gateway for the two boxes to connect directly). I just wish I could remember the name of the ASIC manufacturer for the part inside. It just seems like overkill to throw an 80 MIPs multi-processor part at something that's already done in a single low-cost ASIC. But then again the fun may be in the effort! Enjoy...

David

Franz Achatz

David,

a lot of things are already done but ......

I was thinking about just using uncompressed audio, the same way they do it here:

http://www.maxim-ic.com/appnotes.cfm/an_pk/609

Maybe the MAX542 is not needed and the sample rate could be lower for telephone quality.

best regards

Franz

Graham Stabler

Sounds good, as it is a walkie talkie and only one person talks at a time it does not matter if there are delays, it will be a bit like waiting for someone to type on an instant messenger. I'm not sure why everyone thinks it has to be as good as a real voip product its just fun fun fun, an internet intercom.

Graham

Jamesx

Franz:

I think you should try it. Based on your success with the "New Propeller Board" you pulled together, I would expect you to pull it off nicely. Plus, my (selfish) reason for suggesting you do it is that you might post the method/code. This would enable others of us to learn and follow along.

Jim C

Graham Stabler

Eventually Parallax could add a push to talk button under peoples names on the forum and sell a little module (made by Franz)

[noparse]:D[/noparse]

Franz Achatz

guys,

i think i will give it a try and start my first testings with UDP, when there is some spare time left.
As far as i can see, there is no special hardware needed, besides the ENC28J60 Ethernetchip.

have fun
Franz

deSilva

I just try it a third and last time I think my suggestion is simple and feasible.
@Graham: In the worst case (or the normal case?) this is not like havin gaps between letters, buthaving gaps within single letters Such kind of sound stream is no longerunderstandable; it is much worse than a broken record played on a bumpy road...

Different

Franz Achatz said...
i think i have some kind of a "blackout" now.
Maybe its just a stupid idea but is it possible building an Internet Walkie Talkie or an Internet-Speaker???

We have a propeller MIC and Audio Out and a running/working ENC28J60 Ethernet Chip.

Maybe just telefon quality will do it (up to 4khz).

I have received samples of the Dallas DS80C400 and they can do it !!!!!!!!

If Dallas can do it i think the Propeller can do it as well.

have fun

Franz

IMHO, for Internet audio it is necessary much RAM memory. For example - HX512CARD.