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Comment Re:Huh? (Score 5, Informative) 116

Nothing limits you to one bit-per-second per baud. 9600 bps modems were, IIRC, 2400 baud with 4 bits per Hz. (Higher than that it got a bit shady because they started optimizing for being encoded in a digital phone line).

VDSL2 goes up to 32768-QAM, which is 15 bits per symbol. I do not know whether any actual phone lines exist with a sufficient signal-to-noise-ratio to make that coding useful.

Comment Re:Compact Disc error correction (Score 1) 126

The point you miss is that humans also won't notice the loss of a 20 or 40 milliseconds of data as long as the receiving end does something reasonable (e.g. replicating last received packet).

This is not true. Packet loss of less than 1% is detectable by actual customers with typical VoIP phones and the Alaw (or ulaw) codecs. It would be very handy to handle links with 0.3% packet loss, but that requires switching to codecs with built-in PLC, and transcoding is expensive.

Comment Re:Real-world conditions (Score 1) 238

In several markets you can buy petrol which is supposed to reduce losses in the engine. It has the same octane rating as regular petrol.

Whether it actually works I do not know. I like that fuel is a commodity, I resent the recent attempts at changing that. I wonder if I will be able to go to charging stations with special long-running electrons in ten years...

Comment Re:Which is why sometimes small engines ... (Score 1) 238

It really isn't that hard to get very close to the ideal fuel consumption figures, you just have to relearn how to drive instead of going full-throttle/full-brake all the time.

You are driving a car with non-faked figures. Of course you can get close to the official figures.

Relearning does not help you with most modern cars. They cannot physically achieve the numbers listed.

Comment Re:ISDN flashback (Score 1) 126

Modern wide-band codecs use on the order of 50kbps for really high quality voice. If you use 50kbps continuously, you have added 16GB to your data cap each month (or 32GB is you transfer full duplex). Useful perhaps, but your phone would be constantly busy and battery life would suck. What are you going to transfer at 6kBps per second anyway?

Comment Re:Compact Disc error correction (Score 1) 126

100 ms latency is perfectly fine for voice. VoIP from Europe to China with 400ms is surprisingly usable, most users do not notice the walkie-talkie effect. Anyway, it is trivial to do error correction for VoIP with far less than 100ms latency. The easiest solution is to include a digest of the previous packet in the following packet -- if the previous packet arrives later than the following packet or not at all, use the lower-quality data in the following packet. Spread the information across multiple packets and you will be able to handle multiple packet drops of course.

I wish Asterisk would come with a simple-stupid PLC codec mode where it simply appended the previous packet contents in their entirety to the following packet. It would double bandwidth, but packets-per-second would be unchanged, and 128kbps is nothing on most modern lines. The added 20ms latency would be unnoticeable.

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