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Lots of good answers, but there is another one that's important too: echo cancellation. Most telco equipment has very good echo cancellation hardware in it. I
by mikekchar 10y ago
Lots of good answers, but there is another one that's important too: echo cancellation. Most telco equipment has very good echo cancellation hardware in it. It's not impossible to do a decent job in VOIP, but not all of the software does it well. This can be very important when you have high latencies or if you are doing conference calls.
The other main overlooked problem is automatic gain control in software. This one drives me crazy. Most people are too lazy/clueless to set the gain properly on their microphone, so VOIP client makers tend to use automatic gain control to adjust the input. However, it works very differently that what you are used to in a telephone. If someone laughs loudly, or coughs you end up losing the beginning of the next sentence. It can work extremely badly in conjunction with echo cancellation depending on the software -- to the point where the audio can be very difficult to understand.
It's probably my biggest gripe with Google Hangouts because there is no consistent way to shut of AGC on all platforms.
I've written VOIP clients before and it is possible to have incredibly good audio (much better than normal PSTN -- mainly because the codecs are better). But it's very tricky to get it to work on random hardware, with random network conditions and with users who don't want to configure their client optimally.
- asymmetric 10y agoGot any link to good echo cancellation hardware? Not that I'd every buy it, I'm just interested in tech (and businesses) that's not for average consumers.
- 2almalki 10y agoI work at a big telco in the voice group and we still have tons of DMS 100/200/250s. Anyways some interconnections we have require Ditech echo canceller (no idea what model but apparently when we need them, we use spare ones or have to buy them on the used market). We have been migrating traffic to newer equipment and the new gateways have echo cancel built into them (e.g. Genband G9s)
- zbuf 10y agoI'm going to agree with you and take this opportunity to plug http://cleanfeed.net/ http://cleanfeed.net/ We run a free 'VOIP' system that does zero processing on your audio. It's actually for broadcasters who just want to get live audio from A to B, untouched. But as it's two way (and multi-way) we're finding users contacting us to say they're using it for regular 'conferencing'. I suppose we are also doing it ourselves; we used Cleanfeed to communicate when developing Cleanfeed. Elsewhere in the thread people mention jitter etc. issues. In my experience, 200-300ms of latency has much less negative impact on rapport than aggressive audio processing.
- j_s 10y agoThanks for the recommendation! FAQ #1 should be "how does this remain free/why is this not going to disappear"?
- zbuf 10y agoThanks, good suggestion. It's actually on the front page that our free offering is a spin-off of something commercial. But a FAQ to clarify this particular point would be sensible.
- snuxoll 10y agoNot all uses of VoIP are done with software clients, mind you. I manage SIP setups for myself at home as well as at my aunts shop, both of which have physical IP phones instead of softphones. While softphones are certainly useful, most people on a VOIP service of some kind are probably more likely to still use a physical handset, headset, or proper conference phone where echo cancellation is less of an issue since it's either handled by the hardware itself or non-existent in the case of users on a headset.