282 lines
12 KiB
XML
282 lines
12 KiB
XML
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<?xml version="1.0" standalone="no"?>
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<!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
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]>
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<section id="sn-configuring-jack">
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<title>Getting Audio In, Out and Around Your Computer</title>
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<para>
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Before you can begin to use Ardour, you will need to get the audio
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input/output capabilities of your system working and properly configured.
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There are two aspects to this process: getting your audio interface
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(soundcard) working, and configuring it to work with the Jack Audio
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Connection Kit (<ulink url="http://jackaudio.org/">JACK</ulink>).
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</para>
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<section id="sn-jack">
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<title>JACK</title>
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<para>
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It is extremely important to understand that Ardour does not interact
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directly with your audio interface when it is running. Instead, all of the
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audio data signals that Ardour receives and generates are sent to and from
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JACK, a piece of software that routes audio data between an audio interface
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and audio applications, in real time.
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</para>
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<para>
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Traditionally, most of the audio sources that you would want to record, as
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well as a lot of the more significant effects processing, existed outside
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the computer. Consequently one of the biggest issues in integrating a
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computer into the operation of the studio is how to move audio data in and
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out of the computer.
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</para>
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<para>
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However, it is becoming increasingly common for studios to use audio
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sources and effects processing that are comprised completely of software,
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quite often running on the same machine as an audio sequencer or digital
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audio workstation (DAW). A new problem arises in such situations, because
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moving audio in and out of the DAW no longer involves your hardware audio
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interface. Instead, data has to be moved from one piece of software to
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another, preferably with the same kind of sample synchronisation you’d
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have in a properly configured digital hardware system. This is a problem
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that has been solved at least a couple of times (ReWire from PropellerHeads
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and DirectConnect from Digidesign are the two most common examples), but
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JACK is a new design developed as an open source software project, and is
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thusly available for anyone to use, learn from, extend, *fix or modify.
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</para>
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<para>
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New users may not initially realize that by using Jack, their computer
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becomes an extremely flexible and powerful audio tool - especially with
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Ardour acting as the ’heart’ of the system.
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</para>
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</section>
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<section id="getting-audio-working">
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<title>Getting Your Audio Interface Working</title>
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<note>
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<para>
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Although Ardour runs on OS X as well as Linux, this documentation
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describes only a Linux (ALSA) system. The issues faced on OS X tend to be
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entirely different, and are centered mostly on JACK. There are also
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alternative audio device driver families for Linux but they are also not
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discussed here.
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</para>
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</note>
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<para>
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Getting your audio interface working can be the hardest part of setting
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your computer up to run Ardour, or it could be one of the easiest. The
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level of difficulty you will face depends on the type of audio interface
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("soundcard") you are using, the operating system version you are using,
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and your own understanding of how it all works.
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</para>
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<para>
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In an ideal world, your computer already has a working audio interface, and
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all you need do is to start up qjackctl and run JACK. You can determine if
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you face this ideal situation by doing a few simple tests on your machine.
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The most obvious test is whether you’ve already heard audio coming out of
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your computer. If you are in this situation, you can skip ahead to
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<xref linkend="selecting-capture-source"/>.
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</para>
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</section>
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<section id="checking-for-an-audio-interface">
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<title>Checking For an Audio Interface</title>
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<para>
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If you’ve never tried to play audio on your computer before, you should
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use a basic playback program such as play, aplay or possibly xmms. Find an
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audio file on your machine (<command>locate .wav</command> may help here),
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and try to play it. There are several possibilities:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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You may get an error from the program
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</para>
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</listitem>
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<listitem>
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<para>
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You may hear nothing
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</para>
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</listitem>
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<listitem>
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<para>
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You may hear something, but its too quiet
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</para>
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</listitem>
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<listitem>
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<para>
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you may hear something from the wrong loudspeakers.
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</para>
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</listitem>
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</itemizedlist>
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</section>
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<section id="selecting-capture-source">
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<title>Selecting Capture Source</title>
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<para>
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Many audio interfaces, particularly the cheaper varieties that are often
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found built into computers, have ways to plug in both microphones and
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instruments or other audio equipment to be recorded. This immediately poses
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a question: how does Ardour (or any software) know which signal to record,
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the one coming into the microphone input, or the one arriving at the "line
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in" socket? The same question arises also for "high-end" audio interfaces,
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though in different ways.
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</para>
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<para>
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The short answer is: Ardour doesn’t. Instead, this is a choice you have
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to make using a program a program that understands how to control the
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mixing hardware on the audio interface. Linux/ALSA has a number of such
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programs: alsamixer, gamix, aumix, kmix are just a few of them. Each of
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them offers you a way to select which of the possible recordable signals
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will be used for as the "capture source". How you select the preferred
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signal varies from program to program, so you will have to consult the help
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documentation for whichever program you choose to use.
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</para>
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<para>
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There are also a few programs that offer ways to control just one
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particular kind of audio interface. For example, the
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<application>hdspmixer</application> program offers control over the very
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powerful matrix mixer present on several RME audio interface.
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<application>envy24ctrl</application> does the same for a number of
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interfaces built around the common ice1712/envy24 chipset, found in devices
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from M-Audio, Terratec and others. Please note that this quite similar to
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the situation for Windows and MacOS users, where each audio interface often
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comes with its own control program that allows certain critical
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configuration choices to be made.
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</para>
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<section id="problems-with-input-signal">
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<title>"I don’t get any signal when I record …"</title>
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<para>
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The most common problem for first-time audio users on Linux is to try to
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record something and get no signal at all, or alternatively, a very low
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signal. The low signal problem typically arises from one or more of the
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following issues:
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</para>
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<itemizedlist>
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<listitem>
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<para>
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a microphone input plugged into the "line in" socket of the interface.
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The signal levels delivered by microphones are very small, and require
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amplification before they can be used by most audio circuitry. In
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professional recording studios, this is done using a dedicated box
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called a "pre-amplifier". If your audio interface has a "mic input"
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socket, then it has its own pre-amplifier built in, although its
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probably not a very good one. If you make the mistake of plugging a
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microphone into the "line in" socket, you will get either an inaudible
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or very quiet signal.
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</para>
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</listitem>
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<listitem>
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<para>
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the wrong capture source selected in the audio interface’s hardware
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mixer (see above)
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</para>
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</listitem>
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<listitem>
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<para>
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the "capture" gain level in the audio interface’s hardware mixer is
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turned down too low. You will need to use a hardware mixer application
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(as described above) to increase this.
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</para>
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</listitem>
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</itemizedlist>
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<note>
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<para>
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You will notice in the mixer strip for each track in ardour that you can
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change the selection of the monitoring source between input/pre/post.
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Adjusting the fader while watching the ’input’ levels will NOT have
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any affect on the levels. As mentioned above, ardour is dependent on
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external mixer settings for a source level.
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</para>
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</note>
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</section>
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</section>
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<section id="monitoring-choices">
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<title>Monitoring Choices</title>
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<para>
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Its unfortunate that we have to raise this issue at a point in the manual
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where you, the reader, may not even knoiw what "monitoring" means. However,
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it is such an absolutely critical aspect of using any digital audio
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workstation that we need to at least cover the basics here. The only people
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who don’t need to care about monitoring are those who will never use
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ardour to record a live performance (even on performed using a software
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synthesizer).
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</para>
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<para>
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Monitoring is the term we use to describe listening to what ardour is
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recording. If you are playing a guitar and recording it with ardour, you
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can probably hear the guitar’s own sound, but there are many situations
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where relying on the sound of the instrument is completely inadequate. For
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example, with an electronic instrument, there is no sound until the
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electrical signal that it generates has been processed by an amplifier and
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fed to a loudspeaker. But if Ardour is recording the instrument’s signal,
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what is responsible for sending it to the amp+loudspeakers? It can get a
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lot more complex than that: if you are recording multiple performers at the
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same time, each performer needs to hear their own playing/singing, but they
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also probably need to hear some of their colleagues’ sound as well. You
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might be overdubbing yourself - playing a new line on an instrument while
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listening to tracks you’ve already recorded - how do you hear the new
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material as well as the existing stuff?
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</para>
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<para>
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Well, hopefully, you’re convinced that there are some questions to be
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dealt with surrounding monitoring, see <xref linkend="sn-monitoring"/> for
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more in depth information.
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</para>
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</section>
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<section id="using-multiple-soundcards">
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<title>Can I use multiple soundcards</title>
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<para>
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There are really lots of great reasons why you should not even attempt to
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do this. But seriously, save your money for a while and buy yourself a
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properly designed multichannel soundcard.
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</para>
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</section>
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<section id="qjackctl">
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<title>Qjackctl</title>
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<para>
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JACK itself does not come with graphical user interface - to start JACK and
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control it you need to have access to a command line and a basic knowledge
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of Unix-like operating systems. However,
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<ulink url="http://qjackctl.sourceforge.net/">qjackctl</ulink> is a
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wonderful application that wraps JACK up with a graphical interface that is
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both nice to look at and useful at same time. qjackctl is the recommended
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way of using JACK.
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</para>
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<mediaobject>
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<imageobject>
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<imagedata fileref="images/qjackctl.png"/>
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</imageobject>
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</mediaobject>
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<para>
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You should be able to start qjackctl from the “application menu” of
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your system, typically found on the panel/appbar/dock or whatever its
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called that lives at the top/bottom/left/right of your screen.
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</para>
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<para>
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[ need screenshot of GNOME/KDE/OSX menus here ]
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</para>
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</section>
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<!--
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<xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
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href="Some_Subsection.xml" />
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-->
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</section>
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