diff options
Diffstat (limited to 'manual/xml/jack.xml')
| -rw-r--r-- | manual/xml/jack.xml | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/manual/xml/jack.xml b/manual/xml/jack.xml new file mode 100644 index 0000000000..1e0a0bfd5e --- /dev/null +++ b/manual/xml/jack.xml @@ -0,0 +1,281 @@ +<?xml version="1.0" standalone="no"?> + +<!DOCTYPE section PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [ + +]> + +<section id="sn-configuring-jack"> + <title>Getting Audio In, Out and Around Your Computer</title> + <para> + Before you can begin to use Ardour, you will need to get the audio + input/output capabilities of your system working and properly configured. + There are two aspects to this process: getting your audio interface + (soundcard) working, and configuring it to work with the Jack Audio + Connection Kit (<ulink url="http://jackaudio.org/">JACK</ulink>). + </para> + + <section id="sn-jack"> + <title>JACK</title> + <para> + It is extremely important to understand that Ardour does not interact + directly with your audio interface when it is running. Instead, all of the + audio data signals that Ardour receives and generates are sent to and from + JACK, a piece of software that routes audio data between an audio interface + and audio applications, in real time. + </para> + + <para> + Traditionally, most of the audio sources that you would want to record, as + well as a lot of the more significant effects processing, existed outside + the computer. Consequently one of the biggest issues in integrating a + computer into the operation of the studio is how to move audio data in and + out of the computer. + </para> + + <para> + However, it is becoming increasingly common for studios to use audio + sources and effects processing that are comprised completely of software, + quite often running on the same machine as an audio sequencer or digital + audio workstation (DAW). A new problem arises in such situations, because + moving audio in and out of the DAW no longer involves your hardware audio + interface. Instead, data has to be moved from one piece of software to + another, preferably with the same kind of sample synchronisation you’d + have in a properly configured digital hardware system. This is a problem + that has been solved at least a couple of times (ReWire from PropellerHeads + and DirectConnect from Digidesign are the two most common examples), but + JACK is a new design developed as an open source software project, and is + thusly available for anyone to use, learn from, extend, *fix or modify. + </para> + + <para> + New users may not initially realize that by using Jack, their computer + becomes an extremely flexible and powerful audio tool - especially with + Ardour acting as the ’heart’ of the system. + </para> + </section> + + <section id="getting-audio-working"> + <title>Getting Your Audio Interface Working</title> + <note> + <para> + Although Ardour runs on OS X as well as Linux, this documentation + describes only a Linux (ALSA) system. The issues faced on OS X tend to be + entirely different, and are centered mostly on JACK. There are also + alternative audio device driver families for Linux but they are also not + discussed here. + </para> + </note> + + <para> + Getting your audio interface working can be the hardest part of setting + your computer up to run Ardour, or it could be one of the easiest. The + level of difficulty you will face depends on the type of audio interface + ("soundcard") you are using, the operating system version you are using, + and your own understanding of how it all works. + </para> + + <para> + In an ideal world, your computer already has a working audio interface, and + all you need do is to start up qjackctl and run JACK. You can determine if + you face this ideal situation by doing a few simple tests on your machine. + The most obvious test is whether you’ve already heard audio coming out of + your computer. If you are in this situation, you can skip ahead to + <xref linkend="selecting-capture-source"/>. + </para> + </section> + + <section id="checking-for-an-audio-interface"> + <title>Checking For an Audio Interface</title> + <para> + If you’ve never tried to play audio on your computer before, you should + use a basic playback program such as play, aplay or possibly xmms. Find an + audio file on your machine (<command>locate .wav</command> may help here), + and try to play it. There are several possibilities: + </para> + + <itemizedlist> + <listitem> + <para> + You may get an error from the program + </para> + </listitem> + <listitem> + <para> + You may hear nothing + </para> + </listitem> + <listitem> + <para> + You may hear something, but its too quiet + </para> + </listitem> + <listitem> + <para> + you may hear something from the wrong loudspeakers. + </para> + </listitem> + </itemizedlist> + </section> + + <section id="selecting-capture-source"> + <title>Selecting Capture Source</title> + <para> + Many audio interfaces, particularly the cheaper varieties that are often + found built into computers, have ways to plug in both microphones and + instruments or other audio equipment to be recorded. This immediately poses + a question: how does Ardour (or any software) know which signal to record, + the one coming into the microphone input, or the one arriving at the "line + in" socket? The same question arises also for "high-end" audio interfaces, + though in different ways. + </para> + + <para> + The short answer is: Ardour doesn’t. Instead, this is a choice you have + to make using a program a program that understands how to control the + mixing hardware on the audio interface. Linux/ALSA has a number of such + programs: alsamixer, gamix, aumix, kmix are just a few of them. Each of + them offers you a way to select which of the possible recordable signals + will be used for as the "capture source". How you select the preferred + signal varies from program to program, so you will have to consult the help + documentation for whichever program you choose to use. + </para> + + <para> + There are also a few programs that offer ways to control just one + particular kind of audio interface. For example, the + <application>hdspmixer</application> program offers control over the very + powerful matrix mixer present on several RME audio interface. + <application>envy24ctrl</application> does the same for a number of + interfaces built around the common ice1712/envy24 chipset, found in devices + from M-Audio, Terratec and others. Please note that this quite similar to + the situation for Windows and MacOS users, where each audio interface often + comes with its own control program that allows certain critical + configuration choices to be made. + </para> + + <section id="problems-with-input-signal"> + <title>"I don’t get any signal when I record …"</title> + <para> + The most common problem for first-time audio users on Linux is to try to + record something and get no signal at all, or alternatively, a very low + signal. The low signal problem typically arises from one or more of the + following issues: + </para> + + <itemizedlist> + <listitem> + <para> + a microphone input plugged into the "line in" socket of the interface. + The signal levels delivered by microphones are very small, and require + amplification before they can be used by most audio circuitry. In + professional recording studios, this is done using a dedicated box + called a "pre-amplifier". If your audio interface has a "mic input" + socket, then it has its own pre-amplifier built in, although its + probably not a very good one. If you make the mistake of plugging a + microphone into the "line in" socket, you will get either an inaudible + or very quiet signal. + </para> + </listitem> + <listitem> + <para> + the wrong capture source selected in the audio interface’s hardware + mixer (see above) + </para> + </listitem> + <listitem> + <para> + the "capture" gain level in the audio interface’s hardware mixer is + turned down too low. You will need to use a hardware mixer application + (as described above) to increase this. + </para> + </listitem> + </itemizedlist> + + <note> + <para> + You will notice in the mixer strip for each track in ardour that you can + change the selection of the monitoring source between input/pre/post. + Adjusting the fader while watching the ’input’ levels will NOT have + any affect on the levels. As mentioned above, ardour is dependent on + external mixer settings for a source level. + </para> + </note> + </section> + </section> + + <section id="monitoring-choices"> + <title>Monitoring Choices</title> + <para> + Its unfortunate that we have to raise this issue at a point in the manual + where you, the reader, may not even knoiw what "monitoring" means. However, + it is such an absolutely critical aspect of using any digital audio + workstation that we need to at least cover the basics here. The only people + who don’t need to care about monitoring are those who will never use + ardour to record a live performance (even on performed using a software + synthesizer). + </para> + + <para> + Monitoring is the term we use to describe listening to what ardour is + recording. If you are playing a guitar and recording it with ardour, you + can probably hear the guitar’s own sound, but there are many situations + where relying on the sound of the instrument is completely inadequate. For + example, with an electronic instrument, there is no sound until the + electrical signal that it generates has been processed by an amplifier and + fed to a loudspeaker. But if Ardour is recording the instrument’s signal, + what is responsible for sending it to the amp+loudspeakers? It can get a + lot more complex than that: if you are recording multiple performers at the + same time, each performer needs to hear their own playing/singing, but they + also probably need to hear some of their colleagues’ sound as well. You + might be overdubbing yourself - playing a new line on an instrument while + listening to tracks you’ve already recorded - how do you hear the new + material as well as the existing stuff? + </para> + + <para> + Well, hopefully, you’re convinced that there are some questions to be + dealt with surrounding monitoring, see <xref linkend="sn-monitoring"/> for + more in depth information. + </para> + </section> + + <section id="using-multiple-soundcards"> + <title>Can I use multiple soundcards</title> + <para> + There are really lots of great reasons why you should not even attempt to + do this. But seriously, save your money for a while and buy yourself a + properly designed multichannel soundcard. + </para> + </section> + + <section id="qjackctl"> + <title>Qjackctl</title> + <para> + JACK itself does not come with graphical user interface - to start JACK and + control it you need to have access to a command line and a basic knowledge + of Unix-like operating systems. However, + <ulink url="http://qjackctl.sourceforge.net/">qjackctl</ulink> is a + wonderful application that wraps JACK up with a graphical interface that is + both nice to look at and useful at same time. qjackctl is the recommended + way of using JACK. + </para> + <mediaobject> + <imageobject> + <imagedata fileref="images/qjackctl.png"/> + </imageobject> + </mediaobject> + <para> + You should be able to start qjackctl from the “application menu” of + your system, typically found on the panel/appbar/dock or whatever its + called that lives at the top/bottom/left/right of your screen. + </para> + + <para> + [ need screenshot of GNOME/KDE/OSX menus here ] + </para> + </section> +<!-- + <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" + href="Some_Subsection.xml" /> + --> +</section> |