As mentioned previously, high-quality digital audio data is among the most substantially sized data available (second only to digital video) and as such consumes vast amounts of hard disk space, and causes even more problems when transferring between computers across a network such as the World Wide Web .
If digital audio consumes roughly 1,400,000 bits of data for every second of CD -quality audio, consider one minute of CD quality digital audio sampled at 44.1 kHz, in stereo, with 16 bits per sample. 44.100 Hz means that 44.100 values per second come in from the soundcard (or input file). Multiply that by two because there are two channels. Multiply by another factor of two because there are two bytes per value (twice as much data is used if the sample is 16 bit rather than 8-bit, resulting in a clearer sound quality). The sample will take up
44.100 samples/s x 2 bytes /sample x 2 channels x 60 s/min = around 10 Megabytes
of storage space on a computer's hard disk. Downloading a file of that size over the Internet, given an average 28.8 modem, would take
10 000 bytes x 8 bits /byte / (28.800 bits/s x 60 s/min) = around 49 minutes. [23]
Bandwidth is a measurement of how much information can be transmitted between two points in a given period of time, and as shown above, is a major concern when transmitting data over the Internet . Bandwidth is the maximum speed at which a modem operates - therefore various speeds of modem transmit and receive data at different bandwidths. A 2400 bps modem transmits and receives 2400 bits per second of information, which is approximately 240 characters (a single letter, number or punctuation mark).
A 28.8kbps (thousand bits per second) modem transmits or receives 2880 characters per second, twelve times faster than a 2400 bps modem. Most domestic modems run at 14.4, 28.8 or 56 kbps, and though there are ways of transferring data at higher bandwidths, these are used primarily by corporate LANs (Local Area Networks) or entertainment-based web-sites . A T-1 is a special data line that transfers data at around 15440 kbps, while a T-3 line runs 28 times faster than a T-1. An alternative that is fast becoming economically viable and increasing in popularity is the ISDN system, which at its most basic transmits data at around 128kbps. The more powerful the modem, the less time it takes to transmit the data from one terminal to another.
The problems facing musicians or companies wishing to use music on their web-sites are obvious, especially considering the short attention span of the average casual Internet user. The very thought of downloading music from the Internet complicates matters even more. While companies claim to be able to sell music cheaper than in the shops, or even give it away for free, from their web-sites, the telephone costs involved in waiting for a three-minute pop song to download over several hours was certainly a hindrance in establishing the Internet as a viable investment for the music industry.
As technology improves, faster modems are introduced which increases the available bandwidth and allows for greater use of multimedia on company web-sites . In 1991, it would have taken 14 hours to download a three-minute pop song with a standard 2.4 kbps modem . By the year 2000 Jupiter Communications predict that the same clip will take less than 38 seconds to download with a 400 kbps modem (see table below).
Year |
Modem Speed |
Time |
|---|---|---|
1991 |
2.4 kbps |
14 hrs |
1996 |
28.8 kbps |
13 mins |
1998 |
56.6 kbps |
7 mins |
2003 |
400 kbps |
38 secs |
Increasing bandwidth by using a faster modem is known as using a bigger pipe (allowing more data to flow through the system at a greater rate) and is only one of the ways technological advancements have learned to deal with the problems of transferring large files over computer networks.
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