I mentioned in yesterday's post the biggest negative of a NAS (Network Attached Storage) is the time it takes to load data to it and offload from it. This is a big problem for people who rely upon a NAS for that very purpose; getting data onto and off of a storage device quickly - and who do it often. But, when it comes to building a music library that's not really an issue since we only occasionally load a big library. So we've concluded that for purposes interesting to us, a NAS is a good device. We also learned the big value add of a NAS, vs. other external storage devices: its access from any device on the network and its built in computer. It's to this last bit we'll focus on today. The built in computer on a NAS is needed for several reasons, chief among them is the requirement that network access demands. Because computers are not directly connected to anything over a network, like they are with their internal components, everything on the network must be translated to a language capable of being transported over great distances and through many different machines. The traffic on your home network is identical to the traffic on the internet. That language consists of a group of packets, or containers, holding a chunk of data. Each container has an address and a set of instructions, and each is an independent entity. When I send you this email, the data containing the words I am writing are broken up into small packets and mailed to your address. The route it takes may differ from second to second, day to day. Like a clever mailman who takes different routes to deliver your letters, depending on the traffic and time of day. The job of the NAS internal computer is to receive this stream of packets, make sure they are the correct ones, containing the right data, and assemble them into the proper order. Once collected, they are turned back into their original form as if they lived inside of your computer. This process takes computer power, supplied by what's built into the NAS. So, that is the first job of this computer - and it's main function. Arranging and receiving data into packets, and distributing them where they need to go. Think of this process like the job the railroads do. A long freight train has many cars, each loaded with different cargo going to different locations. The train (your ethernet cable or WIFI signal) is a long stream containing lots of different cars filled with "stuff" and an address for each car to eventually go. The computers at each end of the line sort and distribute the goods on cars to where they should go. There is no direct connection to your computer. The same info you access on your NAS can, if you set it up right, travel around the world or from your office to your music room, with exactly the same results and sound quality. Read that statement again. Unlike USB, S/PDIF, or analog signals, the data over a network is agnostic as to how far it had to travel, how many switches it went through to get there, or what type of wire or WIFI signal was used to move it. When you download a track from a music service, like Blue Coast or HD Tracks, how it got to you does not matter. When Cookie sends you the San Francisco Symphony via download, it leaves a big server somewhere, travels by land line, satellite, microwave, fiber optic, hundreds of switches and machines. It's broken apart, then reassembled back at your computer–some of the packets going one way, others another–all without any degradation or action on your part. And that track sounds the same if it traveled over your home network or around the world twice. This is important to understand, because it's one of the strengths of network audio - the transmission of data does not affect sound quality. The same cannot be said for USB. Aha! you say. I have heard that the quality of the ethernet cable matters. Perhaps that's true, though I have not experienced it. But even if it were true, it would have more to do with electrical and noise issues rather than data accuracy - which is unaffected by the purity of the copper or the time it took to get there. Lastly, there are no jitter issues with network audio signals. We shall continue tomorrow.
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