Hi, I have "used" skype and other voip things for a while now. If you are receving echo from the other end, it suggests something is wrong at the other end. Basically, it means that audio you are sending is getting into the mic circuit of the remote endpoint.
It can happen if the remote end is using a loudspeaker and microphone. Your words are coming out the loudspeaker, and being detected by the microphone, and then sent back to you. It can happen when the remote person uses the internal mic and speaker of a laptop. The best way to eleminate echo is to get both ends to have headphones and mics. This makes it hard for the audio to go from the "speaker" to the mic. However, alsa can cause some problems. With the appropriate adjustment inside alsamixer, you can get alsa to send audio from the output side of things to the microphone side of things. If you are calling to a regular telphone with skype, all bets are off. If the remote phone system is badly configured, you will get echo. There is plenty of dtmf decoder software available for linux that works just fine. However, if the dtmf decoder software is asked to detect dtmf in an audio stream that has been compressed/decompressed with a telephony codec, all bets are off. This has been recognized as "not reliable". skype is heavy on the network - it tends to cause the conversation to delay a bit when used over a dialup connection to the internet. Derek. =============================================================== On Sat, 7 Jan 2006, Andrew Errington wrote: > On Sat, 07 Jan 2006 08:16, you wrote: > > Sounds fantastic! > > > > Have you had it up and running with Linux? > > > > I assume you can dial as well? As in, does the linux stuff have a dtmf > > decoder software for the sound card (as I can see there's no dtmf > > receiver built in to the hardware). > > > > What about incoming calls? Is there any ring generation at this point? > > > > Cheers Don > > "Sounds fantastic" might be an inappropriate comment. It seem to suffer > from echo at the other end, which may be inherent in the design. > > I have not had it running with Linux, but all it is is an equivalent of a > microphone and speakers, so is OS neutral. > > I don't know if there is DTMF detection in software for Linux, I downloaded > and installed the Windows chat-cord code. This does detect and decode > DTMF, so you can drive Skype with the telephone keypad. Bit flaky though. > > There is no ring generation (that's a bit tricky...). In all, worth the $5 > and 30mins I spent building it, but not quite there yet. > > In other news, I just discovered Gizmo. This is a similar thing to Skype, > but uses SIPphone and standard VOIP. It may be preferable to Skype for two > reasons. > > 1) Uses open, standard protocols > 2) Does not use excessive resources on your PC (apparently Skype uses your > PC as part of its own network for processing and call routing.) > > Andy > -- Derek Smithies Ph.D. Any fool can write code that IndraNet Technologies Ltd. a computer can understand. Email: [EMAIL PROTECTED] Good programmers write code ph +64 3 365 6485 that humans can understand. Web: http://www.indranet-technologies.com/ Martin Fowler
