Media Mathematics...

WHAT IS BANDWIDTH?

In computer networking and computer science, bandwidth, network bandwidth, data bandwidth[3] or digital bandwidth is a bit rate measure of available or consumed data communication resources expressed in bits/second or multiples of it (kilobits/s, megabits/s etc.).

Network bandwidth capacity

In computer networking, bandwidth in bit/s sometimes means the net bit rate (also known as peak bit rate, information rate or physical layer useful bit rate), channel capacity, or the maximum throughput of a logical or physical communication path in a digital communication system. For example, bandwidth tests measure the maximum throughput of a computer network. The reason for this usage is that according to Hartley's law, the maximum data rate of a physical communication link is proportional to its bandwidth in hertz, which is sometimes called frequency bandwidth, spectral bandwidth, RF bandwidth, signal bandwidth or analog bandwidth.

Multimedia bandwidth

Digital bandwidth may also refer to: multimedia bit rate or average bitrate after multimedia data compression (source coding), defined as the total amount of data divided by the playback time

list of bitrates in multimedia.

56 kbit/s Modem / Dialup
1.5 Mbit/s ADSL Lite
1.544 Mbit/s T1/DS1
10 Mbit/s Ethernet
11 Mbit/s Wireless 802.11b
44.736 Mbit/s T3/DS3
54 Mbit/s Wireless 802.11g
100 Mbit/s Fast Ethernet
155 Mbit/s OC3
300 Mbit/s Wireless 802.11n
622 Mbit/s OC12
1 Gbit/s Gigabit Ethernet
2.5 Gbit/s OC48
9.6 Gbit/s OC192
10 Gbit/s 10 Gigabit Ethernet
100 Gbit/s 100 Gigabit Ethernet



WHAT IS BITRATE?

In telecommunications and computing, bitrate (sometimes written bit rate, data rate or as a variable R or fb) is the number of bits that are conveyed or processed per unit of time.

The bit rate is quantified using the bits per second (bit/s or bps) unit, often in conjunction with an SI prefix such as kilo- (kbit/s or kbps), mega- (Mbit/s or Mbps), giga- (Gbit/s or Gbps) or tera- (Tbit/s or Tbps). Note that, unlike many other computer-related units, 1 kbit/s is traditionally defined as 1,000 bit/s, not 1,024 bit/s, etc, also before 1999 when SI prefixes were introduced for units of information in the standard IEC 60027-2.

The formal abbreviation for "bits per second" is "bit/s" (not "bits/s", see writing style for SI units). In less formal contexts the abbreviations "b/s" or "bps" are often used, though this risks confusion with "bytes per second" ("B/s", "Bps"). 1 Byte/s (Bps or B/s) corresponds to 8 bit/s (bps or b/s).

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Multimedia bit rate
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In digital multimedia, bit rate often refers to the number of bits used per unit of playback time to represent a continuous medium such as audio or video after source coding (data compression). The size of a multimedia file in bytes is the product of the bit rate (in bit/s) and the length of the recording (in seconds), divided by eight.

In case of realtime streaming multimedia, this bit rate measure is the goodput that is required to avoid interrupts. For streaming multimedia without interrupts, we have the following relationship:

Multimedia bit rate = Required goodput

The term average bitrate is used in case of variable bitrate multimedia source coding schemes.

A theoretical lower bound for the multimedia bit rate for lossless data compression is the source information rate, also known as the entropy rate.

Entropy rate ≤ Multimedia bit rate

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Prefixes
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When quantifying large bit rates, SI prefixes (also known as Metric prefixes or Decimal prefixes) are used, thus:
1,000 bit/s rate = 1 kbit/s (one kilobit or one thousand bits per second)
1,000,000 bit/s rate = 1 Mbit/s (one megabit or one million bits per second)
1,000,000,000 bit/s rate = 1 Gbit/s (one gigabit or one billion bits per second)

Binary prefixes have almost never been used for bitrates, although they may occasionally be seen when data rates are expressed in bytes per second (e.g. 1 kByte/s or kBps is sometimes interpreted as 1000 Byte/s, sometimes as 1024 Byte/s). A 1999 IEC standard (IEC 60027-2) specifies different abbreviations for Binary and Decimal (SI) prefixes (e.g. 1 kiB/s = 1024 Byte/s = 8192 bit/s, and 1 MiB/s = 1024 kiB/s), but these are still not very common in the literature, and therefore sometimes it is necessary to seek clarification of the units used in a particular context.

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Audio Bitrate(MP3)
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* 32 kbit/s – MW (AM) quality
* 96 kbit/s – FM quality - This is questionable since FM broadcast is transmitted in analog 30hz-15khz. Similarly one cannot compare directly an LP record to CD using kbit/s.
* 128–160 kbit/s – Standard Bitrate quality; difference can sometimes be obvious (e.g. lack of low frequency quality and high frequency "swashy" effects)[citation needed]
* 224–320 kbit/s – VBR to highest MP3 quality. 320 kbit/s comparable, virtually indistinguishable to CD quality.

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Video Bitrate
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* 16 kbit/s – videophone quality (minimum necessary for a consumer-acceptable "talking head" picture using various video compression schemes)
* 128 – 384 kbit/s – business-oriented videoconferencing quality using video compression
* 1.15 Mbit/s max – VCD quality (using MPEG1 compression)[6]
* 3.5 Mbit/s typ - Standard-definition television quality (with bit-rate reduction from MPEG-2 compression)
* 9.8 Mbit/s max – DVD (using MPEG2 compression)[7]
* 8 to 15 Mbit/s typ – HDTV quality (with bit-rate reduction from MPEG-4 AVC compression)
* 19 Mbit/s approximate - HDV 720p (using MPEG2 compression)[8]
* 24 Mbit/s max - AVCHD (using MPEG4 AVC compression)[9]
* 25 Mbit/s approximate - HDV 1080i (using MPEG2 compression)[10]
* 29.4 Mbit/s max – HD DVD
* 40 Mbit/s max – Blu-ray Disc (using MPEG2, AVC or VC-1 compression)[11]


Therefore, i hope the informations given above about Media Mathematics are useful for you. This is not all about Media Mathematics, but i will again try to cover the rest in my next post.