Pd Documentation 3

From 8dbec761cf858ea65900c8a094599857208d8c3a Mon Sep 17 00:00:00 2001 From: "N.N." Date: Tue, 5 Jan 2010 22:49:36 +0000 Subject: svn path=/trunk/; revision=12907 --- desiredata/doc/1.manual/x3.htm | 790 ----------------------------------------- 1 file changed, 790 deletions(-) delete mode 100644 desiredata/doc/1.manual/x3.htm (limited to 'desiredata/doc/1.manual/x3.htm') diff --git a/desiredata/doc/1.manual/x3.htm b/desiredata/doc/1.manual/x3.htm deleted file mode 100644 index 9bc0f537..00000000 --- a/desiredata/doc/1.manual/x3.htm +++ /dev/null @@ -1,790 +0,0 @@ - - - - - Pd Documentation 3 - - - - - - - -

Pd Documentation chapter 3: Getting Pd to run

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- back to table of contents -

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Pd runs under Irix, Microsoft Windows, Linux, and MacOS 10.2 (Jaguar). -How to get Pd up and running depends on your operating system, -but the overall strategy is the same. -You must first get and install it, and -then untangle whatever problems arise in handling audio and MIDI input -and output, and finally get Pd to meet its real-time obligations reliably. - -

Installation instructions are platform-specfic; the following four -sections -will describe what to do for various operating systems you might have. -In case of trouble also consult the Pd mailing list archive on - - http://iem.kug.ac.at/mailinglists/pd-list/ -, which often has late-breaking news about configuration problems and solutions. -The rest of this section describes how to get audio and MIDI to work. - -

3.1. Audio and MIDI

- -

-To test audio and MIDI, start Pd and select "test Audio and MIDI" from the -"Media" menu. You should see a window like this: - -

- test tone patch -

- -

First, try to get Pd to play a sine wave over your speakers. The "TEST -TONE" control at top left turns this on and off. Normally, all the output -channels are turned on so that when you turn the tone on (to a soft -40 dB or a -louder -20 dB) you should get output on the first six of your output channels. -(If you have fewer than six output channnels open, the extra -channels aren't played; and if you have more, this particular patch won't -use them.) - -

If there's anything wrong, the most likely outcome is that you will hear -nothing at all. This could be for any of at least three reasons: Pd might -have failed to open the audio device; the audio card's output volume might -be set to zero; or your audio system might not be set to amplify the computer -output. - -

The number boxes labeled "AUDIO INPUT" show the levels of incoming -audio, in dB, with 100 being maximum. (Incoming signals may clip at -RMS levels below 100; for instance, a sinusoid clips at about 97 dB.) -Any DC present in the input (such as you get with cheap audio hardware) -will show up as level unless you turn on the "input hipass" toggle -at right; then the DC component is filtered out before metering. - -

To test the quality of audio input and output, turn on "monitor" -(also at right) which causes the inputs to be played to the outputs at -unit gain. You should hear a faithful, non-distored copy of whatever is -sent through the patch. - -

It is easy to get two copies of Pd running by accident; on most machines -only one at a time may be inputting and outputting sound. (Some copy of Pd -might have audio or MIDI devices open and prevent the copy you're trying to use -from getting access to them.) Having extra -copies of Pd around will also eat CPU cycles uselessly. - -

-You may be interested in getting only audio output or audio input, or -you may need both to run simultaneously. By default, Pd will try to run -both, but if you don't need either input or output, you may find that Pd -runs more reliably, or at least more efficiently, with the unused direction -turned off. This may be specified in Pd's command line flags or using the -"audio settings" dialog panel. - -

-Depending on your application you will have a more or less stringent latency -requirement. Ideally, when any input (audio, MIDI, keyboard, network) is -available, the outputs (in particular the audio output) should react instantly. -In real life, it is necessary to buffer the audio inputs and outputs, trying -always to keep some number of milliseconds ahead of real time to prepare for the -inevitable occasions where the CPU runs off to service some different task -from Pd. How small this latency can be chosen depends on your OS and your -audio driver. - -

TIP: If Pd starts up but you get distortion or glitches in the audio -output, this could be either because the "audio I/O buffer" isn't big enough, -or else because the CPU load of the patch you're running is too great for the -machine you have, or else because the ADC and DAC are out of sync or even at -different sample rates. To test for the first possibility, try increasing the -audio latency in the command line or the "audio settings" dialog (but see also -under your OS below.) For the second, start up your favorite performance -monitor program; and for the third, try starting Pd up with ADCs disabled. - -

In addition to the "test audio and MIDI" patch, the "Media" menu -contains items for controlling audio and MIDI settings. The first two -items, "Audio on" and "Audio off", open or close the audio devices and -start or stop Pd's audio computation. - -

If there is a choice of -audio API to make, the Media menu will display them. (On Linux, they are -OSS, ALSA, and Portaudio; on Windows, you get MMIO and ASIO). More information -about the APIs appears in the sections below. - -

Next is the "Audio settings..." menu item, which opens a dialog like this: - -

- audio settings dialog -

- -The exact choices you get depend on the operating system and API. The sample -rate controls both audio output and input. The audio throughput delay is -the nominal amount of time, in milliseconds, that a sound coming into the -audio input will be delayed if it is copied through Pd straight to the -output. Naturally you would like this to be as small as possible, but, -depending on OS, API, and even the specific choice of audio hardware, there -will be a limit to how small you can make this. You can typically get -10 msec on linux (and lower still if you use special tricks), 30 msec on Mac -OSX, and 60 msec on Windows (but note that there might be ways that a -patient Windows user can reduce this). - -

Next you get a choice of input and output device. If you want to open -more than one, hit "use multiple devices" and you'll be allowed up to 4 -in and 4 out. Each audio device is 2 channels by default, but you may -specify more if your hardware supports it. - -Other parameters may be tweaked using the command line; see under - preferences and startup options . - -

MIDI

- - The "channel message" midi objects in Pd -such as notein or pgmout will take channels 1-16 to mean the first open MIDI -port, 17-32 the second one, and so on. The midiin, sysexin, midiout objects -give you a separate inlet to specify which of the open MIDI port numbers -you want. - -

System exclusive MIDI message input and output is theoretically supported -in version 0.37 but does not work correctly on windows, even in 0.38. - - -

3.2. Installing Pd in Microsoft Windows

- -

Pd should work under any version of Windows since 95. You can download as -a self-extracting archive (a ".exe" file). Run this and select a destination -directory when prompted, such as "\pd" or "Program Files\pd". - -

If for example you put Pd in "C:Program Files\pd", the executable program -will be "C:Program Files\pd\bin\pd". You can simply adjust your path to -include C:\pd\bin and then invoke "pd" in a command prompt window. You can also -make a shortcut to the executable program (left-click on it and drag to the -desktop, for example.) - -

Pd requires "TCP/IP networking" to be turned on. This doesn't mean you -have to be on a real network, but simply that Pd actually consists of two -programs that make a "network link" (locally) to intercommunicate. - -

Audio in Microsoft Windows

- -

-You can ask for a list of audio and MIDI devices by typing -"pd -listdev"; you can then specify which audio and MIDI device to use. -Type "pd -help" (or make any mistake) to get the syntax for specifying -which device to use. You can modify the Pd shortcut (or batch file) to -set these, or else use the "startup" dialog (file menu) to specify -startup arguments. - -

-Alternatively, (and especially when just starting out) you can experiment -with different audio configurations using the "audio settings" -item in the Media menu. - -

-You can list and -choose MIDI devices in the same way as audio; note that, by default, MIDI -input is disabled in Windows (because it's possible to hang up some MIDI -devices if Pd exits unexpectedly). - -

-MIDI timing is very poor if you are using simultaneous audio input and output; -if you suppress either audio input or output things will improve somewhat under -NT; you can apparently get the jitter down to ~40 msec. On W95 performance is -simply terrible. W98, with either audio input or output suppressed, offers -fairly good MIDI timing (~5 msec jitter). The "first edition" used to crash -occasionally; this might be fixed in the "second edition". - -

ASIO

- -

As of version 0.35 Pd supports ASIO. Invoke Pd as "pd -asio" and, if -needed, specify "-sounddev" (etc.) flags to specify which device (see -"the Pd command line" below.) You can also specify a "-blocksize" different -from the default (256 samples) and "-audiobuf" in milliseconds. Pd will -round this down to a power of two buffers, each of "-blocksize" in sample -frames. - -

3.3. Installing Pd in Linux

- -

What to do depends on which flavor of Linux you are running (e.g., Debian -or Red Hat). The instructions here should work for Pd 0.33 and up regardless of -your situation. (If not, you can read the Pd mailing list archives for -recent problems; if you have found a new problem you're welcome to post it -to the list.) - -

If you're running RedHat or Mandrake you might want to use RPM to install -Pd. For other linux distributions, download the "tar.gz" version and compile -Pd. - -

Getting Pd as an RPM

- -

Download Pd, perhaps from - - http://www.crca.ucsd.edu/~msp/software.html , -to a file such as "pd-0.33-0.i386.rpm". -Open a "shell" window, cd to -the directory containing the file, and type the command, -

-    rpm -i pd-0.33-0.i386.rpm
-

- -

(substituting the real file name.) Then you should be able to type "pd" -to a shell and watch the Pd main window appear. - -

Getting Pd as a .tar.gz

- -

Before you start, you might want to check that you have the resources Pd -needs. The main things you need are the C compiler, X windows (including -the X development package for Pd to link against) and TK. If you're running -Redhat or Mandrake 7.x or up, I think these are all present by default. -The RedHat X client developer "RPM" package is called XFree86-devel. - -

-Download Pd, perhaps from - - http://www.crca.ucsd.edu/~msp/software.html , -to file such as "pd-linux-033.tar.gz". Open a "shell" -window, cd to -the directory containing the file, and type the command, -

-    tar xzf pd-linux-033.tar.gz
-

which creates a directory named "pd". I do this from my home directory. -Next, compile it. "CD" to pd and read the INSTALL.txt, or else just cd -to "pd/src" and type - -

-
./configure -
make depend -
make -

- -

You can pass flags to "configure" to customize your compilation: - -

-    To enable debugging (and losing code optimization) add "--enable-debug".
-    To use Portaudio version 19 (experimental), add "--enable-portaudio".
-    To put Pd in /usr/bin instead of /usr/local/bin, add "--prefix=/bin".
-

- -Alsa and Jack support should auto-configure, but "--enable-alsa" od -"--enable-jack" will force their inclusion. - -

After "make", just type "~/pd/bin/pd" to run pd. - -

Alternatively, as superuser, you can run "make install" after "make depend" -and then anyone on your system can just type "pd" to run it. - -

Testing audio and MIDI.

- -

-Next try audio. We want to know whether audio output works, whether audio -input works, and whether they work simultaneously. First run "aumix" (or -any newer audio mixer app) to -check audio input and output gains and learn which input (mic; line; -etc.) is "recording". -Then test audio output by running -

-    pd -noadc
-

and selecting "test audio and MIDI" from the "Media" menu. You should see -a patch. Turn on the test tone and listen. Do the usual where's-the-signal -business. - -

-Then quit Pd and test audio input via -

-    pd -nodac
-

Re-open the test patch and hit "meter"; look at the levels. 100 dB is a -hard clip; arrange gains so that the input signal tops out around 80 or 90, -but no higher. - -

Now see if your audio driver can do full duplex by typing "pd" with no -flags. If you see error messages involving /dev/dsp or /dev/dsp2, you're -probably not able to run audio in and out at the same time. If on the other -hand there's no complaint, and if the audio test patch does what you want, you -might wish to experiment with the "-audiobuffer" flag to see what values of -audio latency your audio system can handle. - -

Audio hardware in Linux

- -

-Be forewarned: installing and testing audio and MIDI drivers in Linux can take -days or weeks. There apears to be no single place where you can get detailed -information on Linux audio. One good source of information lives at: - -http://www.djcj.org/LAU/guide/index.php . - -

-There are two widely-used driver sets, called "OSS" and "ALSA". OSS is -included in the standard Linux kernels since version 2.2. However, for some -audio cards you can find newer versions than are included in the kernel -releases. You can get ALSA from - - - http://www.alsa-project.org/ . - -

ALSA is able to emulate OSS, so that you can usually run Pd using the -default "OSS" settings even if it's actually ALSA that's running. -ALSA is newer, hence less stable and harder to use, than OSS. -Installing ALSA can be tricky and/or confusing. - -

By default, Pd uses OSS. If you are running ALSA, Pd will use ALSA's OSS -emulation. To make Pd use ALSA "natively", i.e., the way ALSA is designed -to be used, include the "-alsa" flag in the command line or bang on the "media" -menu items. - -

You can add ALSA devices by name on the Pd command line: -

-    pd -alsaadd loupgarou
-

-instructs Pd to offer the 'loupgarou' audio device in the Audio Settings panel. - -

Experiences with particular soudcards

- -

-Here are some of my own experiences with sound cards so far. See -also the Pd mailing list archives. - -

RME 9652 (Hammerfall)

- -

This is the best sound card out there; it costs around $500 and has 3 ADAT -I/O ports and one SPDIF. There is a "baby hammerfall" also, which I think is -the "9632." DO NOT CONFUSE THE 9652/9632 WITH OTHER RME BOARDS WHICH MIGHT -NOT WORK WITH PD. - -

The easiest way to use -Hammerfall boards in Pd is via ALSA and jack; but you can use ALSA alone: -

-    pd -alsa -channels 26
-

-works for me. If you don't specify the number of channels correctly Pd crashes. - -

MIDIMAN

- -

Midiman sells PCI devices (delta 44, 66, 1010, and 1010LT) -with between 4 and 10 channels in and out, for -which there are ALSA drivers. These are also very good, and they are a -bit cheaper than Hammerfalls. The driver name is "ice1712". - -

Alsa provides an "envy24control" program (in "utils". You should run -this and check that your ice1712's sync source is internal if you have no -SPDIF input, or "SPDIF" if you do. I think the default is now "internal" -but don't take it for granted... - -

warning about i810/i815 drivers...

- -

As of RedHat 7.0, motherboards with native i810 audio systems didn't work in -full duplex (they crashed linux). Either run Pd -noadc or else (better) -install ALSA. This ought to be fixed by now... - -

3.4. Installing Pd in Macintosh OSX

- -

Pd version 0.35 and up support Macintosh OSX. You need the OSX Jaguar -distribution (10.2) or later. - -

To install Pd you can always just download the sources and compile them -yourself, or (easier) just download the Mac binary from the download page: - - -http://crca.ucsd.edu/~msp/software.html. - -This is in the form of a compressed Tar archive; just click on it and the Max -will extract the Pd application. Open this and you should be running. - -

The package by Hans-Christoph Steiner, on - - -http://at.or.at/hans/pd/installers.html, - -has many updates and extensions -which are not included in the original Pd distribution. Download this and -follow the (simple) instructions found there. -

- -

To install on OSX from source:

- -

-Whether you've downloaded the source or the "package" you can -always compile Pd for yourself, whether to make your own improvements, or -possibly so that you can get the newest version before it shows up compiled for -Mac OS X. - -

To be able to compile Pd, you must have installed Tcl/Tk -specifically in -/Applications/Wish Shell.app -and /Library/Frameworks/Tk.framework and /Library/Frameworks/Tcl.framework. - -

First download and install TK for OSX. I get it from: - -http://tcltkaqua.sourceforge.net/. - - -

Then, just as for linux, just unload pd-whatever.tar.gz into a directory -such as ~/pd-0.36-0, cd to pd-0.36-0/src, type "./configure" -and "make". Then type ~/pd-0.36-0/bin/pd to a shell and enjoy! - -

If you wish you can put a line such as, - -

-    alias pd ~/pd/bin/pd
-

- -

in the file, ~/.tcshrc, so that you can later just type "pd" to a shell. -(The -shell only reads the ~/.tcshrc file on startup, so this won't take effect in -any existing shells unless you specially type -

-    source ~/.tcshrc
-

to them.) - -

Follow the general directions above for testing audio and/or MIDI -as needed. - -

To get MIDI working, you have to do the Mac OSX magic to get a USB -MIDI interface installed. I've seen this done with Midisport devices and -I think you just download the OSX driver and follow directions. - -

3.5. Installing Pd in IRIX (SGI machines)

- -

(NOTE: as of release 0.35 I haven't had an IRIX machine to compile -Pd on. Soeren Bovbjerg has kindly compiled 0.35 and 0.36 for IRIX; -you can find these at - http://www.cvmt.dk/~sb/ .) - -

Download Pd, which will be a "tar.Z" file. You can unpack this by -typing "zcat [name].tar.Z | tar xf -" to a shell. This creates a directory -named "pd". - -

-Starting with release 0.25, Pd should come in "n32" and "o32" versions. -"o32" is the default and will run on IRIX 5.x and up. "n32" runs faster, -but only on 6.x and up. Also, "externs" have to be updated for n32. The -"pd" executable (bin/pd in the distribution) is a symbolic link to either -"pd-o32" or "pd-n32." - -

NOTE: "externs" appear to be broken in the N32 version... I'm not sure -how long this has been true. If you want to use external objects, you have -to use the O32 version. - -

-If for example you put Pd in ~, the executable program -will be ~/pd/bin/pd. The program looks at its command line to -figure out where it is, so it's best to invoke Pd by its full pathname. -You should always invoke Pd from a Unix shell because many important -messages appear on the standard error. - -

-The simplest way to invoke Pd is to -make an alias in your ".cshrc" file (assuming you use the "c" shell) such as: -

-
-    alias pd ~/pd/bin/pd
-
-

(assuming your Pd distribution landed in ~, for example). - -

-Pd will open the "default" audio input and output devices, without regard -for whether they are in sync or not. This will be bad if they aren't; use -the "-noadc" or "-nodac" flag to disable either the input or output. Pd is -supposed to handle up to 8 channels of audio in and/or out. (But at least -one user had to recompile Pd on his Onyx to get 8 channels working.) - -

-As to MIDI, Pd simply attempts to open all available MIDI devices for input and -output, which is probably very bad on anything more recent than my Indy. If -any MIDI ports fail to open either for input or output, all MIDI is disabled. - -

Pd has not been fixed to request real-time priority from Irix; it will -compete with all other processes on your machine for CPU time. - -

Audio and MIDI in IRIX

- -

-Pd takes command line arguments to set the number of input and output channels -and the sample rate. These don't affect the SGI's audio settings, which you -have to set separately using the "audio panel." Pd does detect the audio -sample rate if you don't specify one on the command line. - -

-On SGI machines, you have to work to get MIDI running. Before you start Pd, verify -that least one MIDI port is configured open. Pd opens the FIRST MIDI port -that's open. You might want to get rid of the "software" MIDI port if you're -running 6.x. On Indys, the usual practice is to open serial port number 2 -because some systems configure port 1 as "console" by default. You can use the -GUI if you want, or else just type -

-
-    startmidi -d /dev/ttyd2
-
-

- -

to get port 2 speaking MIDI, and - -

-
-    stopmidi
-
-

- -

to stop it. You can test whether MIDI is configured by typing, - -

-
-    ps -dafe | grep midi
-
-

- -

and looking for "startmidi" processes. - -

-It's a good idea to connect your serial port to your MIDI interface before -typing the "startmidi" command, not afterward, at least in 5.x. We use the -Opcode Studio 3 interface but in principle any Mac-compatible one should work. - -

-The O2 apparently has RS232 ports, not RS422. I think SGI's web site says -something about how to deal with this. - -

3.6. Preferences and startup options

- -

Pd's behavior may be customized to instruct it where to find files, which -audio devices to open, what font size to use, and so on. Most of -these may also be changed using the various dialogs you can open from Pd's -menus. Others take effect only when Pd starts up; some of these appear -on the ``startup" dialog and some of them, too cranky to put in a GUI, must -be typed as command line arguments . - -

In addition to the Audio and MIDI settings (see - Audio and MIDI ), you can customize font size (from the -``edit" menu), directories to search for files (see - How Pd searches for files ), and additional startup -parameters described below. - -

All of these settings may be saved automatically between Pd sessions. -It is also possible to specify settings directly via the command -line . (A third mechanism, using configuration files, is deprecated and -isn't described here.) The Pd command line is described in the next -section. Command line settings, if given, each override the corresponding -setting that was saved from Pd. - -

The startup settings (i.e., those that take effect only when Pd is started) -are controlled using the ``startup..." dialog from the File menu. The -dialog appears as follows: - -

- startup dialog -

- -The slots at top each specify a binary ``library" for Pd to load on startup. -These may be for Gem, pdp, zexy, iemlib, cyclone, and so on. Typically, a -single binary object (an ``extern") is left for Pd to load automatically; -startup library loading is appropriate for collections of many objects -specified by a single binary library. - -

The ``defeat real-time scheduling" contol, if enabled, makes Pd run without -its usual effort to become a real-time process (whatever this means in the -operating system you are using.) In Unix, Pd must usually be setuid to allow -real-time scheduling at all. - -

The ``startup flags" allow you to add to Pd's command line on startup. This -is specified as described below, except that the initial word, ``pd", is -understood. For example, putting ``-rt" in this field sets real-time -scheduling; ``-sleepgrain 1" sets the sleep grain to 1 (see under MIDI below), -and typing "-rt -sleepgrain 1" does both. - -

You may save the current settings for future Pd sessions with the -``save all settings" button; this saves not only the path but all other -settings as well. - -

Command line arguments

- -

Pd may be run as a "command line" program from your "terminal emulator," -"shell," or "MSDOS prompt." In Windows, if Pd is started using a "shortcut" -it is also run from a command line which you can edit using the ``properties" -dialog for the shortcut. In any operating system, Pd can be called from a -script (called a batch file on Windows or a shell script -on OSX or unix). The command line is just a line of text, which should be -of the form: - -

-
-    pd [options] [patches to open]
-
-

- -

although you may have to specify a path (such as "~/pd/bin/pd" or -"C:\program files\pd\bin\pd") so your command interpreter can find -Pd. Possible options include: - -

-
-audio configuration flags:
--r <n>           -- specify sample rate
--audioindev ...  -- sound in device list; e.g., "2,1" for second and first
--audiooutdev ... -- sound out device list, same as above 
--audiodev ...    -- specify both -audioindev and -audiooutdev together
--inchannels ...  -- number of audio in channels (by device, like "2" or "16,8")
--outchannels ... -- number of audio out channels (by device)
--channels ...    -- specify both input and output channels
--audiobuf <n>    -- specify size of audio I/O buffer in msec
--blocksize <n>   -- specify audio I/O block size in sample frames
--sleepgrain <n>  -- specify number of milliseconds to sleep when idle
--nodac           -- suppress audio output
--noadc           -- suppress audio input
--noaudio         -- suppress audio input and output (-nosound is synonym) 
--listdev         -- list audio and MIDI devices
-
-(linux specific audio:)
--frags <n>       -- specify number of audio fragments (defeats audiobuf)
--fragsize <n>    -- specify log of fragment size ('blocksize' is better...)
--oss            -- use ALSA audio drivers
--alsa           -- use ALSA audio drivers
--pa             -- use portaudio (experimental version 19)
--alsadev <n>     ----- obsolete: use -audiodev
--32bit             ---- (probably obsolete) -- use 32 bit OSS extension
-
-(Windows specific audio:)
--mmio           -- use MMIO drivers and API
--asio           -- use ASIO drivers and API
-
-MIDI configuration flags:
--midiindev ...   -- midi in device list; e.g., "1,3" for first and third
--midioutdev ...  -- midi out device list, same format
--mididev ...     -- specify -midioutdev and -midiindev together
--nomidiin        -- suppress MIDI input
--nomidiout       -- suppress MIDI output
--nomidi          -- suppress MIDI input and output
-
-general flags:
--path <path>     -- add to file search path
--nostdpath       -- don't search standard ("extra") directory
--stdpath         -- search standard directory (true by default)
--helppath <path> -- add to help search path
--open <file>     -- open file(s) on startup
--lib <file>      -- load object library(s)
--font <n>        -- specify default font size in points
--verbose         -- extra printout on startup and when searching for files
--version         -- don't run Pd; just print out which version it is
--d <n>           -- specify debug level
--noloadbang      -- suppress all loadbangs
--stderr          -- send printout to standard error instead of GUI
--nogui           -- suppress starting the GUI
--guiport <n>     -- connect to pre-existing GUI over port 'n'
--guicmd "cmd..." -- substitute another GUI program (e.g., rsh)
--send "msg..."   -- send a message at startup (after patches are loaded)
--rt or -realtime -- use real-time priority (needs root privilege)
--nrt             -- don't use real-time priority
-
-

- -

Here are some details on some of the audio, MIDI, and scheduler options (but -see also the next section on file management.) - -

multiple devices.

- -

You can specify multiple MIDI input and output devices. For example, -"pd -midiindev 3 -midioutdev 4,2" asks for the third MIDI input device and the -fourth and second MIDI output device. - -

Audio device selection is similar, except that you can also specify -channels by device: "-audioindev 1,3 -inchannels 2,8" will try to open device 1 -(2 channels) and device 3 (8 channels.) - -

sample rate.

- -

The sample rate controls Pd's logical sample rate which need not be that of -the audio input and output devices. If Pd's sample rate is wrong, time will -flow at the wrong rate and synthetic sounds will be transposed. If the output -and input devices are running at different rates, Pd will constantly drop frames -to re-sync them, which will sound bad. You can disable input or output if this -is a problem. - -

audio buffer size and block size

- -

You can specify an audio buffer size in milliseconds, typically between 10 and -300, depending on how responsive your OS and drivers are. If this is set too -low there will be audio I/O errors ("data late"). The higher the value is, -on the other hand, the more throughput delay you will hear from the audio -and/or control inputs (MIDI, GUI) and the audio coming out. - -

You can also specify the audio block size in sample frames. This is 64 by -default (except for MMIO for which it's 256), and may be 64, 128, or 256. - -

MIDI and sleepgrain

- -

In Linux, if you -ask for "pd -midioutdev 1" for instance, you get /dev/midi0 or /dev/midi00 -(or even /dev/midi). "-midioutdev 45" would be /dev/midi44. In NT, device -number 0 is the "MIDI mapper", which is the default MIDI device you selected -from the control panel; counting from one, the device numbers are card -numbers as listed by "pd -listdev." - -

The "sleepgrain" controls how long (in milliseconds) Pd sleeps between -periods of computation. This is normally the audio buffer divided by 4, but -no less than 0.1 and no more than 5. On most OSes, ingoing and outgoing MIDI -is quantized to this value, so if you care about MIDI timing, reduce this to 1 -or less. - -

3.7. How Pd searches for files

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Pd has a search path feature; you specify the path on the command line -using the "-path" option. Paths may contain any number of files. If you -specify several files in a single "-path" option they're separated by colons -in unix or semicolons in NT. - -

You can see and edit the path while Pd is running using the "path..." -item in the "File" menu: - -

- startup dialog -

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The path must be correctly set before you load -a patch or it may fail to find abstractions, etc., that are needed to -construct the patch. When Pd searches for an abstraction or an -"extern" it uses the path to try to find the necessary file. The "read" -messages to qlists and arrays (aka tables) do this too. - -

If ``use standard extensions" is enabled, the usual ``extras" directory -is also searched. This contains standard external objects like ``expr" and -``fiddle", and perhaps much more depending on the distribution of Pd -you're using. - -

You may save the current settings for future Pd sessions with the -``save all settings" button; this saves not only the path but all other -settings as well. - -

Path entries may be relative to the patch directory; for instance, -if your path has an item, "../sound", and your patch is in "my stuff/all mine", -then Pd will look in "my stuff/sound". Spaces should be OK in the path to -the patch, but not in the path entry (../sound) itself. This is useful if -you have a patch and supporting files (even a supporting snapshot of pd) -that you want to distribute or carry around together. - -

Regardless of path, Pd should look first in the directory containing -the patch before searching down the path. Pd does not automatically look -in the current directory however; to enable that, include ``." in -the path. The ``extra" directory, if enabled, is searched last. - -

Filenames in Pd are always separated by (unix-style) forward slashes, even -if you're on Windows (which uses backslashes). This is so that patches can be -ported more easily between operating systems. On the other hand, if you -specify a filename on the command line (as in "pd -path c:\pdlib") the file -separator should agree with the operating system.
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If a filename specified in a patch has any "/" characters in it, the "path" -is not used; thus, "../sounds/sample1.wav" causes Pd only to look relative to -the directory containing the patch. You may also invoke externs that way. - -

As of version 0.35, there may be spaces in the path to Pd itself; also, -the "openpanel" and "savepanel" objects can handle spaces. Spaces in the -path should work as of version 0.38. - - - - - -- cgit v1.2.1