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Digital audio playlist

01 Introduction - what is digital audio?

02 Binary and digital data

03 Data size, data capacity and data rate

04 The six physical forms of digital data

05 What is an analogue to digital audio converter?

06 Analogue to digital audio conversion - The 2 primary parameters

07 Analogue to digital audio conversion - Sample rate

08 Analogue to digital audio conversion - Nyquist theory

09 Analogue to digital audio conversion - Aliasing

10 Analogue to digital audio conversion - Word length and quantisation

11 Analogue to digital audio conversion - Common word lengths

12 Analogue to digital audio conversion - Setting record levels

13 Down sampling and dither

14 Uncompressed digital audio file formats

15 Compressed digital audio file formats

16 Digital audio interconnection signal types

17 Digital audio synchronisation

18 Connecting audio devices with Toslink leads

19 Connecting audio devices with AES3 or SPDIF coaxial leads

20 Latency

Digital audio 07
Analogue to digital audio conversion - Sample rate

Level of challenge Intermediate


Stills from the video will appear here.


Welcome to this video on audio sample rate.


We have already learnt that analogue to digital audio converters work by repeatedly measuring the amplitude of an incoming electrical pressure soundwave, and outputting these measurements as a long list of binary bytes.


Caption - What is a sample?

Although it is common during a recording session to use the word "sample" to refer to a complete sound such as single note of an instrument, or a drum break loop, in digital theory a "sample" refers to a single measurement of amplitude. Each measurement is recorded as a single binary byte.

In digital theory a sample may also be referred to as ...

a snapshot

.. or ..
a sample measurement

Caption - What is sample rate?

Sample rate is simply the number of samples, or measurements of amplitude, taken per second.


Sample rate is also known as Sample Frequency. For example, the sample rate of CD quality audio is often expressed as "44.1kHz", meaning simply that the audio data stream contains 44,100 measurements of amplitude per second.


Incidentally, sample rate is also sometimes referred to as Sample Bandwidth.


Caption - Don't confuse sample and audio frequency

It is important not to confuse "sample frequency" with the "audio frequency" of the sound wave being converted. Sample frequency is independent of the frequency of the sound wave being converted.


For example CD, quality audio has a sample rate, or frequency, of 44.1kHz, whatever the frequency of the sound wave being converted. So low bass at 40Hz and high frequency sounds such as triangles will both be converted at a sample rate of 44,100 measurements of amplitude per second.


Caption - Sample rate is constant

Once a sample rate setting has been chosen, sample rate does not vary during a recording. However, different audio files recorded at different sample rates may be used together in a multitrack system if the software permits it. Usually, as in the case of a DAW, audio files of differing sample rates will need to conform, or be converted too, a single common sample rate. This sample rate is usually set in the application preferences for the recording session.


Caption - Choosing sample rates

Choosing an approriate sample rate for a recording session is a critical, but one which is made easier due to 2 factors.


Firstly, at the time this video is being produced, there are four established and commonly used sample rates to choose from. They are ..




.. and ..


Higher sample rates produce better quality recordings but also bigger file sizes which demand greater space on storage devices, such as hard drives. Processing and editing also requires more powerful CPUs. In general, choosing a higher sample rate will reduce the number of simultaneous tracks and real-time processes that a digital recording system, such as a DAW, can handle.

Lower sample rates produce poorer quality but also smaller file sizes which demand less of storage systems and CPUs, and which will transfer more quickly across networks.


Because the audible improvement between medium and high sample rates is not always apparent, most recording is still done at 44.1kHz or 48kHz, but this may change as CPU power, network bandwidth and storage capacity increases and there is no longer any disadvantage in recording at higher rates.


The second factor which affects choice of sample rate is to do with a studio setup. Because it can be inconvenient and time consuming to reconfigure a digital studio to a different sample rate, it is often easier to adopt the existing studio sample rate, providing it isn't set at an inadequate rate such as 32kHz.


Caption - Thanks for watching

The script for this video, with accompanying images, can be found at 


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Thanks for watching.

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