parent"><ahref=/ardour-tutorial/en/introduction/><b>1. </b>Introduction</a><ul><lidata-nav-id=/ardour-tutorial/en/introduction/conventions/title=Conventionsclass=dd-item><ahref=/ardour-tutorial/en/introduction/conventions/>Conventions</a></li><lidata-nav-id=/ardour-tutorial/en/introduction/what-is-digital-audio/title="What is digital audio?"class="dd-item active"><ahref=/ardour-tutorial/en/introduction/what-is-digital-audio/>What is digital audio?</a></li></ul></li><lidata-nav-id=/ardour-tutorial/en/getting-started/title="Getting started"class=dd-item><ahref=/ardour-tutorial/en/getting-started/><b>2. </b>Getting started</a><ul><lidata-nav-id=/ardour-tutorial/en/getting-started/starting-ardour-on-ubuntu/title="Starting Ardour"class=dd-item><ahref=/ardour-tutorial/en/getting-started/starting-ardour-on-ubuntu/>Starting Ardour</a></li><lidata-nav-id=/ardour-tutorial/en/getting-started/overview-of-the-interface/title="Overview of the Interface"class=dd-item><ahref=/ardour-tutorial/en/getting-started/overview-of-the-interface/>Overview of the Interface</a><ul><lidata-nav-id=/ardour-tutorial/en/getting-started/overview-of-the-interface/editor-window/title="Editor window"class=dd-item><ahref=/ardour-tutorial/en/getting-started/overview-of-the-interface/editor-window/>Editor window</a></li><lidata-nav-id=/ardour-tutorial/en/getting-started/overview-of-the-interface/mixer-window/title="Mixer window"class=dd-item><ahref=/ardour-tutorial/en/getting-started/overview-of-the-interface/mixer-window/>Mixer window</a></li><lidata-nav-id=/ardour-tutorial/en/getting-started/overview-of-the-interface/recorder-window/title="Recorder window"class=dd-item><ahref=/ardour-tutorial/en/getting-started/overview-of-the-interface/recorder-window/>Recorder window</a></li><lidata-nav-id=/ardour-tutorial/en/getting-started/overview-of-the-interface/cue-window/title="Cue window"class=dd-item><ahref=/ardour-tutorial/en/getting-started/overview-of-the-interface/cue-window/>Cue window</a></li></ul></li><lidata-nav-id=/ardour-tutorial/en/getting-started/creating-tracks-and-busses/title="Creating tracks and busses"class=dd-item><ahref=/ardour-tutorial/en/getting-started/creating-tracks-and-busses/>Creating tracks and busses</a></li><lidata-nav-id=/ardour-tutorial/en/getting-started/importing-audio/title="Importing audio"class=dd-item><ahref=/ardour-tutorial/en/getting-started/importing-audio/>Importing audio</a></li><lidata-nav-id=/ardour-tutorial/en/getting-started/setting-up-the-timeline/title="Setting up the timeline"class=dd-item><ahref=/ardour-tutorial/en/getting-started/setting-up-the-timeline/>Setting up the timeline</a></li></ul></li><lidata-nav-id=/ardour-tutorial/en/recording-audio/title=Recordingclass=dd-item><ahref=/ardour-tutorial/en/recording-audio/><b>3. </b>Recording</a><ul><lidata-nav-id=/ardour-tutorial/en/recording-audio/recording-audio/title="Recording audio"class=dd-item><ahref=/ardour-tutorial/en/recording-audio/recording-audio/>Recording audio</a></li><lidata-nav-id=/ardour-tutorial/en/recording-audio/understanding-routing/title="Understanding routing"class=dd-item><ahref=/ardour-tutorial/en/recording-audio/understanding-routing/>Understanding routing</a></li><lidata-nav-id=/ardour-tutorial/en/recording-audio/routing-between-applications/title="Routing between applications"class=dd-item><ahref=/ardour-tutorial/en/recording-audio/routing-between-applications/>Routing between applications</a></li></ul></li><lidata-nav-id=/ardour-tutorial/en/editing-sessions/title="Editing sessions"class=dd-item><ahref=/ardour-tutorial/en/editing-sessions/><b>4. </b>Editing sessions</a><ul><lidata-nav-id=/ardour-tutorial/en/editing-sessions/non-destructive-editing/title="Non-destructive editing"class=dd-item><ahref=/ardour-tutorial/en/editing-sessions/non-destructive-editing/>Non-destructive editing</a></li><lidata-nav-id=/ardour-tutorial/en/editing-sessions/arranging-tracks/title="Arranging tracks"class=dd-item><ahref=/ardour-tutorial/en/editing-sessions/arranging-tracks/>Arrangi
<spanclass=links><ahref=/ardour-tutorial/en/>Home</a> > <ahref=/ardour-tutorial/en/introduction/>Introduction</a> > What is digital audio?</span></div><divclass=progress><divclass=wrapper><navid=TableOfContents><ul><li><ahref=#frequency-and-gain>Frequency and Gain</a></li><li><ahref=#peaks-and-clipping>Peaks and Clipping</a></li><li><ahref=#sample-rate-and-bit-depth>Sample Rate and Bit Depth</a></li></ul></nav></div></div></div></div><divid=head-tags></div><divid=body-inner><h1>What is digital audio?</h1><p><strong>Ardour</strong> is a digital audio workstation (DAW). Beforing using it to record and
edit sound, it might be useful to review how digital audio works.</p><p><imgsrc=en/adc-dac.svgalt=analogue-digital></p><p>The diagram above shows how sound travels to and from your computer. The
Conversion” (DAC) are done by the sound card or audio interface. The digital
system in this case is your computer running Ardour.</p><h2id=frequency-and-gain>Frequency and Gain</h2><p>Imagine a loudspeaker. To move the air in front of it and make sound,
amplitude in <em>decibels</em> (dB).</p><p><imgsrc=en/membrane-vibration.svgalt="speaker membrane vibration"></p><p>Check out the great animation on this page illustrating this process:</p><divstyle=position:relative;padding-bottom:56.25%;height:0;overflow:hidden><iframesrc=https://www.youtube.com/embed/RxdFP31QYAgstyle=position:absolute;top:0;left:0;width:100%;height:100%;border:0allowfullscreentitle="YouTube Video"></iframe></div><p>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
<em>samples</em> (i.e. measurements) made per second is called the <em>sample rate</em>, and
the number of possible values each sample can have is called the <em>bit depth</em>.
The combination of sample rate and bit depth indicates how closely the digital
signal can reproduce the sound it has recorded.</p><h2id=peaks-and-clipping>Peaks and Clipping</h2><p>When Ardour displays the samples which have been recorded, they appear as the
<em>waveform</em> we see below. The center horizontal line indicates the membrane of
the speaker at rest, and the <em>peaks</em> of the waveform indicate the maximum
<em>amplitude</em>.</p><p><imgsrc=en/Ardour4_Digital_Audio_Waveform.pngalt=waveform></p><p>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 <em>clipping</em>, which results in a permanent loss of digital information,
as well as a change in the sound quality which is recognizable as
<em>distortion</em>. Ardour marks clipped peaks with the color red, as can be seen in
the image below.</p><p><imgsrc=en/Ardour4_Digital_Audio_Clipping2.pngalt=clipping></p><p>In the image above, one can also see the <em>mixer strip</em> on the far left,
which gives a running measurement of the peaks, as well as an indication
at the top of the <em>peak meters</em> showing the maximum peak so far. The red number indicates clipping has occurred.</p><divclass="notices tip"><p>Clipping often can happen at the time of recording if you set your microphone levels too high.</p></div><p>The range of decibels between the region’s maximum peak and the clipping point
is commonly referred to as <em>headroom</em>, 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.</p><p>Also, because the peaks of audio signals add together, care must be taken when
<em>mixing</em> several sources together to keep the combined signals from clipping.</p><h2id=sample-rate-and-bit-depth>Sample Rate and Bit Depth</h2><p>To make audio playable on a compact disc, for example, the computer must
generate 44,100 samples per second. The sample rate determines the highest
frequency which can be recorded or played back by the computer. A sampling
rate of 44.1 kHz means that the highest frequency which can be represented is
just under 22.05 kHz. Since normal human hearing lies within the range of
approximately 20 Hz to 20 kHz, this is commonly accepted as a reasonable
sample rate. Other commonly used sample rates include 48 kHz (e.g.
multi-effects pedals) or 96 kHz (DVD audio).</p><p>Each sample is recorded as a 16-bit number. One <em>bit</em> is a piece of
information which is either 0 or 1. If there are 16 bits together to make one
sample, then there are 2^16 (65,536) possible values for each sample.</p><p>Thus, we can say that CD-quality audio has a sample rate of 44.1 kHz and
a <em>bit depth</em> of 16 bits. Professional music recordings are usually mixed
using 24 bits to preserve the highest amount of detail before being mixed down
to 16 bits for CD. Older computer games have a distinctively rough sound,
using only 8 bits. By increasing the sample rate, we are able to record higher
sonic frequencies, and by increasing the bit depth, we are able to use a
greater <em>dynamic range</em> (the difference between the quietest and the loudest
sounds possible to record and play).</p><p>Here is a great video tutorial explaining sampling rate and bit depth in a lot
more detail:</p><divstyle=position:relative;padding-bottom:56.25%;height:0;overflow:hidden><iframesrc=https://www.youtube.com/embed/zC5KFnSUPNostyle=position:absolute;top:0;left:0;width:100%;height:100%;border:0allowfullscreentitle="YouTube Video"></iframe></div><footerclass=footline></footer></div></div><divid=navigation></div></section><divstyle=left:-1000px;overflow:scroll;position:absolute;top:-1000px;border:none;box-sizing:content-box;height:200px;margin:0;padding:0;width:200px><divstyle=border:none;box-sizing:content-box;height:200px;margin:0;padding:0;width:200px></div></div><scriptsrc=/ardour-tutorial/js/clipboard.min.js?1649318705></script>
