diff --git a/content/introduction/what-is-digital-audio/index.en.md b/content/introduction/what-is-digital-audio/index.en.md index b3a8e99..f9a2086 100644 --- a/content/introduction/what-is-digital-audio/index.en.md +++ b/content/introduction/what-is-digital-audio/index.en.md @@ -3,26 +3,11 @@ title = "What is digital audio?" description = "What is digital audio?" chapter = false weight = 3 -#pre = "1. " +++ -**Ardour** is a digital audio workstation (DAW). Beforing using it to record and -edit sound, it might be useful to review how digital audio works. - -![analogue-digital](en/adc-dac.svg) - - B(Analog to digital conversion) - B --> | digital numeric data, samples | C(Digital system) - C --> D(Digital to analog conversion) - D --> E(fa:fa-headphones Analog output) -{{< /mermaid >}} --> - -The diagram above shows how sound travels to and from your computer. The -"Analogue to Digital Conversion" (ADC) and the "Digital to Analogue -Conversion" (DAC) are done by the sound card or audio interface. The digital -system in this case is your computer running Ardour. +**Ardour** is a digital audio workstation (DAW). Beforing using it to +record and edit sound, it might be useful to review how digital audio +works. ## Frequency and Gain @@ -32,57 +17,61 @@ rest) backwards and forwards. The number of times the membrane vibrates each second determines the _frequency_ (the note, or _pitch_) of the sound you hear. The distance the -membrane travels from its resting point determines the _amplitude_ (the volume, -or _loudness_) of the sound. Normally, we measure frequency in _Hertz_ (Hz) and -amplitude in _decibels_ (dB). - -![speaker membrane vibration](en/membrane-vibration.svg) +membrane travels from its resting point determines the _amplitude_ (the +volume, or _loudness_) of the sound. Normally, we measure frequency in +_Hertz_ (Hz) and amplitude in _decibels_ (dB). Check out the great animation on this page illustrating this process: {{< youtube RxdFP31QYAg >}} -A microphone works like a loudspeaker in reverse: vibrations in the air cause -its membrane to vibrate. The microphone turns these acoustic vibrations into -an electrical current. If you plug this microphone into a computer's sound -card and start recording, the sound card makes thousands of measurements of -this electric current per second and records them as numbers. The number of -_samples_ (i.e. measurements) made per second is called the _sample rate_, and -the number of possible values each sample can have is called the _bit depth_. -The combination of sample rate and bit depth indicates how closely the digital -signal can reproduce the sound it has recorded. +A microphone works like a loudspeaker in reverse: vibrations in the air +cause its membrane to vibrate. The microphone turns these acoustic +vibrations into an electrical current. If you plug this microphone into a +computer's sound card and start recording, the sound card makes thousands +of measurements of this electric current per second and records them as +numbers. The number of _samples_ (i.e. measurements) made per second is +called the _sample rate_, and the number of possible values each sample can +have is called the _bit depth_. The combination of sample rate and bit +depth indicates how closely the digital signal can reproduce the sound it +has recorded. ## Peaks and Clipping -When Ardour displays the samples which have been recorded, they appear as the -_waveform_ we see below. The center horizontal line indicates the membrane of -the speaker at rest, and the _peaks_ of the waveform indicate the maximum -_amplitude_. +When Ardour displays the samples which have been recorded, they appear as +the _waveform_ we see below. The center horizontal line indicates the +membrane of the speaker at rest, and the _peaks_ of the waveform indicate +the maximum _amplitude_. -![waveform](en/Ardour4_Digital_Audio_Waveform.png) +{{< figure src="en/Ardour4_Digital_Audio_Waveform.png" alt="Waveform" >}} -If we take a waveform and increase its amplitude a lot, some of the peaks may now fall outside the range that the computer can represent digitally. The computer's inability to represent peaks outside the range of amplitude is called _clipping_, which results in a permanent loss of digital information, -as well as a change in the sound quality which is recognizable as -_distortion_. Ardour marks clipped peaks with the color red, as can be seen in -the image below. +If we take a waveform and increase its amplitude a lot, some of the peaks +may now fall outside the range that the computer can represent digitally. +The computer's inability to represent peaks outside the range of amplitude +is called _clipping_, which results in a permanent loss of digital +information, as well as a change in the sound quality which is recognizable +as _distortion_. Ardour marks clipped peaks with the color red, as can be +seen in the image below. -![clipping](en/Ardour4_Digital_Audio_Clipping2.png) +{{< figure src="en/Ardour4_Digital_Audio_Clipping2.png" alt="Clipping" >}} In the image above, one can also see the _mixer strip_ on the far left, which gives a running measurement of the peaks, as well as an indication -at the top of the _peak meters_ showing the maximum peak so far. The red number indicates clipping has occurred. +at the top of the _peak meters_ showing the maximum peak so far. The red +number indicates clipping has occurred. {{% notice tip %}} -Clipping often can happen at the time of recording if you set your microphone levels too high. +Clipping often can happen at the time of recording if you set your +microphone levels too high. {{% /notice %}} -The range of decibels between the region's maximum peak and the clipping point -is commonly referred to as _headroom_, and common recording practice is to -keep approximately 3 to 6 decibels of headroom between the maximum of your -signal and the clipping point, with the clipping point itself being +The range of decibels between the region's maximum peak and the clipping +point is commonly referred to as _headroom_, and common recording practice +is to keep approximately 3 to 6 decibels of headroom between the maximum of +your signal and the clipping point, with the clipping point itself being represented as 0 dB (zero decibels). In other words, an audio region with a -comfortable amount of Headroom would have its maximum peaks between −6 dB and -−3 dB. +comfortable amount of Headroom would have its maximum peaks between −6 dB +and −3 dB. Also, because the peaks of audio signals add together, care must be taken when _mixing_ several sources together to keep the combined signals from clipping. @@ -115,3 +104,4 @@ Here is a great video tutorial explaining sampling rate and bit depth in a lot more detail: {{< youtube zC5KFnSUPNo >}} +