70 LXF249May 2019 http://www.linuxformat.com
TuTorials Audio editing
if it starts clipping. Depending on your underlying audio
system, you may be able to turn the recording levels
back down with the slider in the top-right of the window.Running tracks
Recording a piece of audio is great, but you can do
that on just about anything. What makes Audacity so
popular is that it does multi-track layered recording,
and probably makes it easier than any other program
out there. If you’re new to the concept of multi-track
recording, it allows you to record sounds one at a time
in layers, slowly building up a soundscape.
For instance, the most common usage is in music
where you may record each musician in isolation, rather
than recording the band as a whole. You may lay down a
drum track first, and with that first drum track in their
headphones, the bassist can record their track in a new
second layer. Then the guitarist could hear the drums
and bass playing through their headphones and record
their guitar in a third layer. With the instrumentals
finished, the singer can record their vocals.
If you’re a seasoned Audacity user, you need to
know that things have changed. When you hit the
Record button, Audacity used to create a new track
automatically and start recording in that. Now when
you click Record, Audacity will start recording on the
end of the current track, and just keep on adding to it.
If you would rather record into a new track, use the
keyboard instead of the mouse. Pressing R records
onto the end of the current track, but Shift+R records
into a new track. If you’re determined to have things the
way they used to be, you can change it by choosing Edit
> Preferences from the main menu. Open the
Recording section and in the Options field, click
‘Always record on a new track’.
Note that Audacity now has latency correction built-
in, but some audio device settings may result in an error
regarding latency timing. If this is the case, you can also
tweak your latency correction settings in the
Preferences window. In the Devices section, you can
tweak the buffer length and ‘Track shift after record’
settings in the Latency field.Track-on-track action
Not only can Audacity do multi-track recording, but you
can also edit each recorded layer individually, making
tweaks to any layer without upsetting the others. Going
back to the band example, if you simply recorded them
in one live image, you would have to mix them together
as a whole and you wouldn’t be able to make many
adjustments. But with separate tracks you can correct
mistakes and tweak each recording individually.
For instance, if the guitarist plays a bum note or the
drummer coughs during silence, you can simply mute
their second of bad audio and the rest of the song will
be unaffected. Or, if one instrument is too loud, you can
turn the volume down on just that track without
affecting the volume levels of any other musician.
If you want to turn a track up or down, just move that
track’s Gain slider. If you wish to mute a second of
audio, simply highlight the portion of audio you don’t
want and press Ctrl+L, or click Edit > Remove Special >
Silence Audio. For more advanced users who want to
do volume automation, there is the Envelope Tool in the
main toolbar. This lets you make smooth volumeDefault or Pulse. Default will probably use ALSA, which
will run much faster, but if you’re using Pulse audio,
open the properties for your sound card. In KDE we had
to open the Advanced tab in the Audio Volume section,
and from the Profile drop-down box, we used Analogue
Stereo Duplex. If you’re using digital speakers, just try
anything that enables an analogue input. Once you have
something that works, write down what you did and
don’t mess with it – record everything you can while it’s
working! After this, Audacity should be smooth sailing.
Now to tweak the recording levels.
The smaller the wave in height, the worse the
signal-to-noise ratio will be, making the track hissy and
probably muffled. The louder the recorded input, the
more likely it will ‘clip’ the edge of the waveform and
sound horrible and distorted. You want to strike a
balance where a good amount of space in the wave
form is used, but leave room in the dynamic range for
sudden loud notes, such as a big cymbal crash. Keep
turning up your instrument, input or mixer desk until
your waveform is getting near the edge, and back it offrecordingWithJAcK
Running Audacity with JACK rather defeats the purpose of its simple
interface, but maybe there’s some kind of effect chain you want to
create, or some kind of MIDI program you need to use, and the only
way to do it is JACK. First, you need to make sure JACK runs
properly. We recommend installing QjackCtl, which provides
a straightforward GUI for starting and configuring JACK.
If you try to start JACK and get an error, first try specifying your
soundcard by clicking Setup, and in the Settings tab will be the
Interface drop-down menu. Change the setting from ‘(default)’ to
your soundcard’s actual device name. If this doesn’t work, make
sure Driver is set to ‘alsa’ instead of ‘dummy’, and if it still doesn’t
work, try disabling ‘Realtime’.
To change Audacity from using ALSA to using JACK, open your
system settings by choosing Edit > Preferences and in the Devices
tab will be the Interface section. For Host, open the drop-down menu
and change the entry from ALSA to ‘JACK Audio Connection Kit’.
It’s best to leave everything at default settings and see if you can
record as-is. If you need more JACK connectivity, you change
Audacity’s Playback and Recording devices to JACK, though you may
need to manually connect ports in QjackCtl’s Connect window. JACK
is messy and temperamental at the best of times. Don’t use it with
Audacity unless you really need to!The Envelope
tool lets you
make smooth
and continual
transitions to
volume over time,
such as a long
fade-out.A coolfeature
veteransmay
notknowabout
istheWave
colorentry
inthedrop-
downmenu,
whichhas
fourdifferent
colours,andis
meantforeasily
differentiating
between
instruments.