Editing Bit rate (section)

=== Audio ===

==== CD-DA ====
[[Compact Disc Digital Audio]] (CD-DA) uses 44,100 samples per second, each with a bit depth of 16, a format sometimes abbreviated like "16bit&nbsp;/&nbsp;44.1kHz". CD-DA is also [[Stereophonic sound|stereo]], using a left and right [[Audio channel|channel]], so the amount of audio data per second is double that of mono, where only a single channel is used.

The bit rate of PCM audio data can be calculated with the following formula:
: <math>\text{bit rate} = \text{sample rate} \times \text{bit depth} \times \text{channels}</math>

For example, the bit rate of a CD-DA recording (44.1&nbsp;kHz sampling rate, 16 bits per sample and two channels) can be calculated as follows:
: <math>44,100 \times 16 \times 2 = 1,411,200\ \text{bit/s} = 1,411.2\ \text{kbit/s}</math>

The cumulative size of a length of PCM audio data (excluding a file [[Header (computing)|header]] or other [[metadata]]) can be calculated using the following formula:
: <math>\text{size in bits} = \text{sample rate} \times \text{bit depth} \times \text{channels} \times \text{time}.</math>

The cumulative size in bytes can be found by dividing the file size in bits by the number of bits in a byte, which is eight:
: <math>\text{size in bytes} = \frac{\text{size in bits}}{8}</math>

Therefore, 80 minutes (4,800 seconds) of CD-DA data requires 846,720,000 bytes of storage:
: <math>\frac{44,100 \times 16 \times 2 \times 4,800}{8} = 846,720,000\ \text{bytes} \approx 847\ \text{MB} \approx 807.5\ \text{MiB}</math>
where '''MiB''' is mebibytes with [[binary prefix]] Mi, meaning 2<sup>20</sup> = 1,048,576.

==== MP3 ====
The [[MP3]] audio format provides [[lossy data compression]]. Audio quality improves with increasing bitrate:
* 32&nbsp;kbit/s{{snd}} generally acceptable only for speech
* 96&nbsp;kbit/s{{snd}} generally used for speech or low-quality streaming
* 128 or 160&nbsp;kbit/s{{snd}} mid-range bitrate quality
* 192&nbsp;kbit/s{{snd}} medium quality bitrate
* 256&nbsp;kbit/s{{snd}} a commonly used high-quality bitrate
* 320&nbsp;kbit/s{{snd}} highest level supported by the [[MP3]] standard

==== Other audio ====
* 700&nbsp;bit/s{{snd}} lowest bitrate open-source speech codec [[Codec2]], but Codec2 sounds much better at 1.2&nbsp;kbit/s
* 800&nbsp;bit/s{{snd}} minimum necessary for recognizable speech, using the special-purpose [[FS-1015]] [[speech encoding|speech codecs]]
* 2.15&nbsp;kbit/s{{snd}} minimum bitrate available through the open-source [[Speex]] codec
* 6&nbsp;kbit/s{{snd}} minimum bitrate available through the open-source [[Opus (audio format)|Opus]] codec
* 8&nbsp;kbit/s{{snd}} [[telephone]] quality using speech codecs
* 32–500&nbsp;kbit/s{{snd}} [[Lossy compression|lossy audio]] as used in [[Ogg Vorbis]]
* 256&nbsp;kbit/s{{snd}} Digital Audio Broadcasting ([[Digital Audio Broadcasting|DAB]]) [[MPEG-1 Audio Layer II|MP2]] bit rate required to achieve a high quality signal<ref>Page 26 of BBC R&D White Paper WHP 061 June 2003, DAB: An introduction to the DAB Eureka system and how it works http://downloads.bbc.co.uk/rd/pubs/whp/whp-pdf-files/WHP061.pdf</ref>
* 292&nbsp;kbit/s{{snd}} Sony [[Adaptive Transform Acoustic Coding]] (ATRAC) for use on the [[MiniDisc|MiniDisc Format]]
* 400&nbsp;kbit/s–1,411&nbsp;kbit/s{{snd}} [[Lossless compression|lossless audio]] as used in formats such as [[Free Lossless Audio Codec]], [[WavPack]], or [[Monkey's Audio]] to compress CD audio
* 1,411.2&nbsp;kbit/s{{snd}} [[Linear PCM]] sound format of [[CD-DA]]
* 5,644.8&nbsp;kbit/s{{snd}} [[Direct Stream Digital|DSD]], which is a trademarked implementation of [[Pulse-density modulation|PDM]] sound format used on [[Super Audio CD]].<ref>Extremetech.com, Leslie Shapiro, 2 July 2001. ''Surround Sound:'' [http://www.extremetech.com/article2/0,2845,1180143,00.asp ''The High-End: SACD and DVD-Audio''.] {{webarchive|url=https://web.archive.org/web/20091230154914/http://www.extremetech.com/article2/0%2C2845%2C1180143%2C00.asp |date=30 December 2009 }} Retrieved 19 May 2010. 2 channels, 1-bit, 2822.4&nbsp;kHz DSD audio (2×1×2,822,400)= 5,644,800&nbsp;bits/s</ref>
* 6.144&nbsp;Mbit/s{{snd}} E-AC-3 (Dolby Digital Plus), an enhanced coding system based on the AC-3 codec
* 9.6&nbsp;Mbit/s{{snd}} [[DVD-Audio]], a digital format for delivering high-fidelity audio content on a DVD. DVD-Audio is not intended to be a video delivery format and is not the same as video DVDs containing concert films or music videos. These discs cannot be played on a standard DVD-player without DVD-Audio logo.<ref>{{cite web |archive-url=https://web.archive.org/web/20120304060434/http://patches.sonic.com/pdf/white-papers/wp_dvd_audio.pdf |url=http://patches.sonic.com/pdf/white-papers/wp_dvd_audio.pdf |title=Understanding DVD-Audio |publisher=Sonic Solutions |access-date=23 April 2014 |archive-date=4 March 2012 }}</ref>
* 18&nbsp;Mbit/s{{snd}} advanced lossless audio codec based on [[Meridian Lossless Packing]] (MLP)