Cable Forum - View Single Post

graf_von_anonym · 13-02-2010, 01:10

It might be worthwhile asking on the Virgin Media newsgroup to see if they can check the UBR/cable that you are connecting through. High levels of error correction might result in corruption of downloads*, as could high CPU-utilisation or something else that is causing random packets to corrupt, which would be enough to throw off files that don't in and of themselves have error correction or are tightly compressed.

There are two reasons that phone support will be looking at speeds, and while you can probably figure the first one out yourself the second is that most of the things that would cause errors in downloads would (or at least could) cause slow speeds on your connection: packet loss; utilisation; throughput delays.

* In that while the equipment does forward error correction extremely short bursts of extremely high errors could be enough to cause the packet to be "corrected" wrong. Sudden burst noise that is short lived, spikes in data like a DDOS attack, or even some underlying condition like Additive White Gaussian Noise could be enough to distort borderline bits of signal up and throw off some packets. Effectively the density of the data that you're downloading makes it more susceptible to these issues - on images because of the nature of the encoding a duff bit or two will give you a bleary pixel or some sort of quasi-steganographic distortion. With something that requires unpacking, a handful of duff bytes could throw the whole thing off.

13-02-2010, 01:10	#39
graf_von_anonym Inactive Join Date: Dec 2008 Location: Castell Anonym Services: BB:NTL XL, TV:L Posts: 141	Re: Download corruption and CRC errors. It might be worthwhile asking on the Virgin Media newsgroup to see if they can check the UBR/cable that you are connecting through. High levels of error correction might result in corruption of downloads, as could high CPU-utilisation or something else that is causing random packets to corrupt, which would be enough to throw off files that don't in and of themselves have error correction or are tightly compressed. There are two reasons that phone support will be looking at speeds, and while you can probably figure the first one out yourself the second is that most of the things that would cause errors in downloads would (or at least could) cause slow speeds on your connection: packet loss; utilisation; throughput delays. In that while the equipment does forward error correction extremely short bursts of extremely high errors could be enough to cause the packet to be "corrected" wrong. Sudden burst noise that is short lived, spikes in data like a DDOS attack, or even some underlying condition like Additive White Gaussian Noise could be enough to distort borderline bits of signal up and throw off some packets. Effectively the density of the data that you're downloading makes it more susceptible to these issues - on images because of the nature of the encoding a duff bit or two will give you a bleary pixel or some sort of quasi-steganographic distortion. With something that requires unpacking, a handful of duff bytes could throw the whole thing off.