- Broadband: any internet connection above 150Kbit/s. Broadband connections are fixed connections to the home or office and do not include mobile phones, or WiFi hotspots. Technologies used include DSL,cable, FTTH and satellite.
- Market share: a company's share of sales or subscriptions in a specific territory.
- Digital Retail: a method of selling digital content that gives the customer ownership over the files they have downloaded, allowing the customer to use the content as many times as they like - the digitally distributed equivalent of conventional retail channels. Digital retail is also known as 'download-to-own', 'electronic sell-thru' and 'digital sell through'
- Digital Rental: pay per view distributed digitally. Commonly customers choose content on an a la carte basis and pay to watch it for a limited period. Content can be downloaded or streamed although at present download is the prevalent method of distribution.
- Penetration: penetration figures in broadband intelligence are always given on a per household basis, unless it is explicitly stated otherwise. e.g Online Households Penetration = (Households with an internet connection/national household total)*100
- "A la carte" downloads: see Transactional downloads
- Transactional downloads are pieces of content consumed and paid for on a per-item basis (e.g. digital retail and digital rental movies are both forms of a la carte download)
- Entertainment PCs are PCs running Windows Media Center or Apple's Front Row. Computers running Linux and dedicated to media use are excluded due to their low market share.
- Average access speed: a weighted average of the download speeds offered by ISPs. The actual speeds achieved by consumers are, in general, lower that the speed listed by their ISP because of a number of factors including contention (see 'Contention ratio' below) and, for DSL, distance from the exchange.
- Contention ratio: the majority of consumer broadband connections are shared between a number of different subscribers. The number of other users that one customer shares a line with is called the contention ratio. Sharing the connection with a large number of other users has can have a significant effect on data throughput especially at peak times when download speed can become significantly lower than the speeds advertised by the ISP. In the UK, the majority DSL lines from the incumbent telco BT are shared by up to 50 other customers giving a contention ratio of 50:1.
- Online TV includes long and short form videos ranging from traditional TV content (sport, drama, news etc) to made-for-the-web videos that feature similar content (e.g. an online cooking demonstration). Online TV excludes music videos, movie trailers, video game trailers, adult content and content distributed through user-generated websites.
UNITS AND NOTATION
Bits and bytes: both bits and bytes are measures of file size; 1 byte equals 8 bits. Following industry convention Screen Digest uses bits when discussing transfer rates and bytes when discussing file sizes.
The conventional notation is as follows:
A capital 'B' indicates 'bytes' while a lowercase 'b' indicates the smaller unit 'bits'. This can lead to some confusion between MB (bytes) and Mb (bits).
KB = Kilobyte
MB = Megabyte
GB = Gigabyte
TB = Terabyte
Mb = Megabit
Kb = Kilobit
Gb = Gigabit
There is no significance attached to the capitalisation of the leading letter e.g. kilobit may appear as either Kb or kb
When discussing data transfer we us the 'kilo' and 'mega' in accordance with industry convention i.e. units are not like scientific units (i.e. 1 kb is not 1,000 bits) but rather the basic unit is 1024 of the previous unit.
1 KB = 1024 bits
1 MB = 1024 kilobits
1 GB = 1024 megabits
When discussing file sizes and device capacity there is so such clear convention and 'kilo' and 'mega' can mean either 1000 or 1024 of the previous unit.
Transfer speeds: are generally written as either
Kbit/s or Kbps = Kilobit per second
Mbit/s or Mbps = Megabit per second
Gbit/s or Gbps = Gigabit per second
Broadband Intelligence tends to use the former as it avoids confusion between bits and bytes.
Relation between file sizes, transfer rates and downloading times
The chart below shows the time needed for a 90' DVD-quality movie to be downloaded, depending on the bitrate/speed of the connection.
A typical 120min movie in DVD-quality compressed using MPEG-4 is approx 2.4 GB
=8*2.4 Gbits
=19.2 Gbits
=1024*19.2 Mbits
= 19600 Mbits.
With a 'one meg' bandwidth connection (1 Mbit/s), it would take up to 19,600 seconds (approx. 5 hours) to download a film under ideal conditions. However, certain other factors have to be taken into account including 'contention ratio' and other data overheads. A realistic value for normal internet usage (average filesize less than 25KB) is 50% overhead, which lengthens the practical downloading time to nearly eight hours.
| File Size | 1Mbps Cable/ADSL | 2Mbps Cable/ADSL | 8Mbps max. Cable/ADSL | 12Mbps ADSL2 | 24Mps ADSL 2+ | 50Mbps VDSL | 100Mbps fibre |
|
| 192Kbps music track (6MB) | 00:00:46 | 00:00:23 | 00:00:06 | 00:00:04 | 00:00:02 | 00:00:01 | 00:00:01 |
| 192Kbps music album (80MB) | 00:10:25 | 00:05:12 | 00:01:18 | 00:00:52 | 00:00:26 | 00:00:13 | 00:00:06 |
| 1hr DVD-quality TV show (1.2GB) | 02:36:15 | 01:18:07 | 00:19:32 | 00:13:01 | 00:06:31 | 00:03:07 | 00:01:34 |
| 2hr below DVD-quality movie (1.4GB) | 03:02:17 | 01:31:08 | 00:22:47 | 00:15:11 | 00:07:36 | 00:03:39 | 00:01:49 |
| 2hr DVD-quality movie (2.4GB) | 05:12:30 | 02:36:15 | 00:39:04 | 00:26:02 | 00:13:01 | 00:06:15 | 00:03:07 |
