• Downloaded (total): 609 time
  
• This file You searched for: audacity nyquist prompt
  
• Rank: 480
  
• checked by moderators: Yes
  
• File verified:McAfee Viruses undetected
  

The Audacity Nyquist PromptAudacity Support Forum /Audacity and Nyquist /Nyquist Ajdacity Manual /Nyquist Examples and TutorialsSteven Jones /Pedro Morales /David Sky /Nyquist and Emacs /Audacity WikiThe Audacity Nyquist PromptWith the Audacity Nyquist Prompt you can test small snippets of Nyquistcode or doing quick audio hacks. On this page the basic usage of the Nyquistprompt is explained.� Preparations� Load a Sound File� Create a Mono Track� Create a Stereo Track� The Nyquist Prompt� The Nyquist Interpreter� The Nyquist DebuggerNote: All [comments] and [explanations] are written in squarebrackets, so they cannot be confused with (Lisp code).1 PreparationsThe Audacity Nyquist prompt is placed in the Audacity 'Effect' menuwhich only can be activated aufacity an Audacity audio track exists and at least apart of it marked or selected [Audacity 1.3.4].Back to top1.1 Load a Sound FileIf you have a mono or stereo sound file available you can load itinto Audacity via:Audacity File menu > Import >Audio or Shift + Control +IIf you have no sound files available you can build yourown mono or stereo tracks via the Audacity 'Generate' menu.Back to top1.2 Create a Mono Track1.

Go to the Audacity 'Generate' menu and choose 'Tone'. Leaveeverything as-is, just click 'OK', a mono track will appear in the Audacitywindow.Back to top1.3 Create a Stereo Track1. Mark the whole mono track from above either by pressing'Ctrl+A' on the keyboard, or by clicking with the mouse into the trackheader, audacity nyquist prompt taking care not to move the buttons or sliders, the whole trackthen will appear in a different color.2.

Go to the 'Edit' menu and choose 'Duplicate'. A second,identical mono track will appear below the first one.3. In the upper mono track, open the track menu by clicking on thesmall black triangle at the top of the track header and coose 'Make stereotrack'. Both mono tracks then will get combined to a single stereotrack.Back to top2 The Nyquist PromptTo enable the Audacity 'Effect' menu at least nyquit part of an Audacity audiotrack must be marked or ajdacity.

Then go to the Audacity 'Effect' menu andchoose 'Nyquist prompt'. A window like the following will appear:Back to top2.1 The Nyquist InterpreterIn the 'Nyquist Prompt' window, type into the text field a string"hello" with quotes:If you click 'OK', you should get a window displaying 'hello':Click 'OK' in the 'hello' window to make it disappear again.Congratulations, you just have learned how audacity nyquist prompt send text messages to theuser.Back to top2.2 The Nyquist DebuggerAfter clicking 'OK' in the 'hello' window, go back to the Audacity'Effect' menu and choose 'Nyquist prompt' again, but this time typehello without the quotes:Important: Now click 'Debug' instead of 'OK'.You should first get a window displaying a 'Nyquist did not return audio'or similar message:After clicking 'OK' in the window auvacity, a second window appears,displaying the detailed Nyquist error messages:Important: The 'Nyquist output' window only appears if you click'Debug' in the 'Nyquist Prompt' window.

If you click 'OK', then, even with aNyquist error, only the first window will appear.Back to topSteven Jones /Pedro Morales /David Sky /Nyquist and Emacs /Audacity WikiAudacity Support Forum /Audacity and Nyquist /Nyquist Reference Manual /Nyquist Examples and Tutorials This page explains how to use the Audacity Nyquist Prompt to test-run Nyquist code snippets.The "Nyquist Basics" tutorials start with very simple examples at the top of each page with increasing complexity towards the end.

You do not necessarily need to work through to the end of each page to be able to understand the other tutorials. If you feel confused, try any of the other Nyquist Basics tutorials, in any order. Every "Basics" page contains lots of notes and hints where you can find extra information.Related article(s):� Digital Audio Technology� Nyquist Audio Programming� Nyquist 3.02 Reference Manual - the latest Nyquist Manual (mostly using SAL syntax)� Nyquist 2.37 Reference Manual - the latest version entirely using LISP syntax Contents� 1 Setting up� 1.1 Load a Sound File� 1.2 Create a Mono Track� 1.3 Create a Stereo Track� 2 The Nyquist Prompt� 2.1 The Nyquist Interpreter� 2.2 The Nyquist Debugger� 2.3 Basic Nyquist Commands� 2.4 Simple Examples� 2.4.1 Applying a DC offset to a signal� audacitj Modulating with a carrier frequencySetting upMake sure you have a audacihy of Audacity that is 1.3.12 (Beta) or older.

Otherwise, please see Nyquist Basics: The Audacity Audaciyt Prompt With SAL.The Audacity Nyquist prompt appears in Audacity's "Effect" menu, which is activated only if an Audacity audio track exists and at least some audio in it is selected. For testing generate commands in Nyquist, you can addNyquist Generate Prompt to the Audacity "Plug-Ins" folder.

Load a Sound FileSound files are imported into Audacity via:File > Import > Audio or the shortcut CTRL + SHIFT + IIf you have no pre-existing sound files to work with, you can create your own mono or stereo tracks via the Audacity "Generate" menu.Create a Mono TrackClick Generate > Tone.

Leave everything as-is and just click "OK". A mono track will appear in the Audacity window:Create a Stereo Track1. Create an empty stereo track.� In Audacity 1.2.x, click Project > New Stereo Track.� In Audacity 1.3.x-beta, click Track > Add New.

> Stereo Track.An empty stereo track will appear in the Audacity window.2. Now click Generate > Tone. Leave everything as-is and audacoty click "OK". The stereo tracks will become filled with the generated sound.The Nyquist PromptSelect the track(s) and click Effect > Nyquist Prompt.

Effects are not activated until at least a portion of the track(s) have been selected. You can select all tracks by pressing CTRL + A on the keyboard.The Nyquist Prompt appears like this:The Nyquist InterpreterIn the Nyquist Prompt window, type (print "hello") into the text field with the parentheses and nyauist, as follows: NOTE: The Nyquist Prompt must see an open parenthesis as the first non-space character; otherwise it will assume this is written using SAL syntax.

Otherwise, we might have just typed "hello", which worked in earlier versions of Audacity.When you click OK, you should get a message box displaying the word hello:The message box disappears when you click OK.This, as you have learned, is how you can send messages to the user.The Nyquist DebuggerAfter clicking OK in the "hello" message box, go back to Effect > Nyquist Prompt, and this time, type (print hello) with the parentheses but without the quotes:Important: This time, click "Debug" instead of "OK".You should first get a window displaying a "Nyquist did not return audio" or a similar message:After clicking OK in the window above, a second window appears, displaying the error messages that Nyquist returned: NOTE: The "Nyquist output" window only appears if you click "Debug" in the "Nyquist Prompt" window.

If you click "OK", then, even with a Nyquist error, only the first window will appear.Basic Nyquist CommandsThe Nyquist manual entirely using LISP nyquisst is here: Nyquist Reference Manual.The current Nyquist manual introducing SAL syntax is here: Nyquist 3.02 Reference Manual.Audacity uses the 's' variable to reference the current audio file/selection. Thus, you can use basic commands such as 'mult' or 'sum' with 's' and the Wudacity prompt will replace the file/selection with the result (or as Audacity calls it, "returned audio").Simple Examples NOTE: These examples are focused upon using Promppt to manipulate digital signals (clearly Audacity is better suited to audio, but nyquizt such as Nyquist can open many other uses).For those interested, the signal used is an infra red (IR) sample from a remote control. NOTE: Each code example will be shown once using LISP syntax, and again using Nyquisf syntax.

Either form can be used, but never try to mix them in a single program or prompt! Prior to Audacity Version 1.3.13 (Beta), only LISP syntax works. Applying a DC offset to a signalOriginal Signal primpt command.Type the following into the Nyquist Prompt (using LISP syntax):(sum s 1)Or type the following equivalent SAL command:return s + 1The whole signal has now audacuty up to above zero.Modulating with a carrier frequencyTo multiply a signal with a generated carrier signal, you canThis page is a list of suggested "how-to" and explanatory articles for Nyquist programmers.

Nyquist is a LISP-based programming language for audio synthesis and analysis written by Roger B.Dannenberg. A number of effects and analysis tools shipped with Audacity are written in Nyquist.

Ptompt interfaces to Nyquist using the somewhat stripped-down and modified Libnyquist library.Many articles herein are still to be written. Feel free to request other topics by clicking the discussion tab at the top of this page.

If you are looking for extra Nyquist plug-ins to use, see Nyquist Plugins.Related article(s):� Nyquist homepage at Carnegie Mellon University� Nyquist Plugins Reference - an overview of plug-in structure and syntax� Other pages in our Digital Audio Technology category Contents� 1 Basic Experiments� 2 Advanced topics� 3 Very advanced topicsBasic ExperimentsExperiments from the Audacity Nyquist prompt:� The Audacity Nyquist Prompt - how it works� Changing the Volume - in different ways� Changing the volume of an Audacity audio track� Changing the Volume of the left and right stereo channels independently� Changing the volume with envelopes - fade in, fade out, etc.� Changing the volume with a low frequency generator - tremolo effect� Nyqust treble and bass - simple equalizer� Simple delay effect� Audio loops with Nyquist - simple loop and echo effects.Advanced topics� Narrowing and widening stereo signals� Removing vocals from a stereo recording� Writing your own Audacity Nyquist plug-ins� Official Audacity Nyquist plug-in documentation� Updated plug-in information, 2007� Nyquist 3.02 Reference Manual - the latest Nyquist manual, most functions described in terms of SAL syntax� Nyquist 2.37 Reference Manual - the latest Nyquist manual using all LISP syntax� XLISP documents collection - XLISP is the programming language Nyquist is based on Please note: The notation in the current Nyquist 3.02 Reference Manual from the links above emphasizes SAL syntax, although the underlying functions are the same.

SAL only works in Audacity 1.3.8 or later.Use the Nyquist 2.37 Manual from the links above if you would like to see functions described using LISP prmpt. These work in any Audacity version. We are currently working on unifying nyquust old Nyquist plug-in documentation on the main Audacity website and the updated information in the German forum into one single place here in the Wiki. The outdated list of Nyquist plug-ins at http://web.audacityteam.org/download/nyquistplug-ins has now been removed.

The only disadvantage of this is that the potential (unused) mechanism for translating the plug-ins list is lost. Translating the list was never a priority as the nnyquist themselves are in English. Possibly we could in time add (at least, German) translations of Wiki Nyquist pages, or even links to German versions of these plug-ins?Very advanced topics� Multiple echoes with different delay times - nyqiust effect� The relations between timeshift and frequency response� Frequency-dependent delays with comb and allpass filters - reverb, chorus, phaser, etc.� Dynamics processing - how to derive control signals from volume behaviour� Auto-equalizing - how to derive control signals from frequency behaviour This page nyquidt how to use the Audacity Nyquist Prompt to test-run Nyquist code snippets.The "Nyquist Basics" tutorials start with very simple examples at the top of each page with increasing complexity towards the end.

You do not necessarily need to work through to the end of each page to be able to understand the other tutorials. If you feel confused, try any of the other Nyquist Basics tutorials, in any order. Every "Basics" page contains lots of notes and hints where you can find extra information.Related article(s):� Digital Audio Technology� Nyquist Audio Programming� Nyquist 3.02 Reference Manual - the latest Nyquist Manual (mostly using SAL syntax)� Nyquist 2.37 Reference Manual - the latest version entirely using LISP syntax Contents� 1 Setting up� 1.1 Load a Sound File� 1.2 Create a Mono Track� 1.3 Create a Stereo Track� 2 The Nyquist Prompt� 2.1 The Nyquist Interpreter� audacjty The Nyquist Debugger� 2.3 Basic Nyquist Commands� 2.4 Simple Examples� 2.4.1 Applying a DC offset to a signal� 2.4.2 Modulating with a carrier frequencySetting upMake sure you have a version of Audacity that is 1.3.12 (Beta) or older.

Otherwise, please see Nyquist Basics: The Audacity Nyquist Prompt With SAL.The Audacity Nyquist prompt appears in Audacity's "Effect" menu, which is activated only if an Audacity audio track exists and at least some audio in it is selected. For testing generate commands in Nyqquist, you can addNyquist Generate Prompt to the Audacity "Plug-Ins" folder.

Load a Sound FileSound files are imported into Audacity via:File > Import > Audio or the shortcut CTRL + SHIFT + IIf you have no pre-existing sound files to work with, you can create your own mono or sudacity tracks via the Audacity "Generate" menu.Create a Mono TrackClick Generate > Tone. Leave everything as-is and just click "OK". A mono track will appear in the Audacity window:Create a Stereo Track1.

Create an empty stereo track.� In Audacity 1.2.x, click Project aidacity New Stereo Track.� In Audacity 1.3.x-beta, click Track > Add New. > Stereo Track.An empty stereo track will appear in the Audacity window.2. Now click Generate > Tone. Leave everything as-is and just click "OK". The stereo tracks will become filled with the generated sound.The Nyquist PromptSelect the track(s) nyquisst click Effect > Nyquist Prompt. Effects are not activated until at least a portion of the track(s) have been selected.

You can select all tracks by pressing CTRL + A on the keyboard.The Nyquist Prompt appears like this:The Nyquist InterpreterIn the Nyquist Prompt window, type (print "hello") into the text field with the parentheses and quotes, as follows: NOTE: The Nyquist Prompt must see an open parenthesis as the first non-space character; otherwise it will assume this is written using SAL syntax.

Otherwise, we might have just typed "hello", which worked in earlier versions of Audacity.When you click OK, you should get a message box displaying the word hello:The message box disappears when you click OK.This, as you have learned, is how you can send messages to the user.The Nyquist DebuggerAfter clicking OK in the "hello" message box, go back to Effect > Nyquist Prompt, and this time, type (print hello) with the parentheses but without the quotes:Important: This time, click "Debug" instead of "OK".You should first get a window displaying a "Nyquist did not return audio" or a similar message:After clicking OK in the window above, a second window appears, displaying the error messages that Nyquist returned: NOTE: The "Nyquist output" window only appears if you click "Debug" in the "Nyquist Prompt" window.

If you click "OK", then, even with a Nyquist error, only the first window will appear.Basic Nyquist CommandsThe Nyquist manual entirely using LISP syntax is here: Nyquist Reference Manual.The current Nyquist manual introducing SAL syntax is here: Nyquist 3.02 Reference Manual.Audacity uses the 's' variable to reference the current audio file/selection.

Nyquisst, you can use proompt commands such as 'mult' or 'sum' with 's' and the Nyquist prompt will replace the file/selection with the result (or as Audacity calls it, "returned audio").Simple Examples NOTE: These examples are focused upon using Audacity to manipulate digital signals (clearly Audacity is better suited to audio, but features such as Nyquist can open many other uses).For those interested, the signal used audacjty an infra red (IR) sample from a remote control. NOTE: Each code example will be shown once using LISP syntax, and again using SAL syntax.

Either form can be used, but never try to mix them in a single program or prompt! Prior to Audacity Version 1.3.13 (Beta), only LISP syntax works. Applying a DC offset to a signalOriginal Signal before command.Type the following into the Nyquist Prompt (using LISP syntax):(sum s 1)Or type the following equivalent SAL command:return s + 1The whole signal has now moved up to above zero.Modulating with a carrier frequencyTo multiply a signal with a generated carrier signal, you can�TourStart here for a quick overview of the site�Help CenterDetailed answers to any questions you might have�MetaDiscuss the workings and policies of this site�About UsLearn more about Stack Overflow the company�BusinessLearn more about hiring developers or posting ads with us Announcing Stack Overflow DocumentationWe started with Q&A.

Technical documentation is next, and we need your help.Whether you're a beginner or an experienced developer, you can contribute.Sign up and start helping >Learn more about Documentation > I wish to use the Nyquist Prompt plugin in Audacity to construct a piece-wise linear waveform of 2048 samples in length. For example, I can generate a square pulse wave by starting with 2048 silent (zero) samples, selecting all, and then invoking the Nyquist Prompt with: (sum s (pwl0 10.5 10.5))This uses the piece-wise linear (pwl) function to create a waveform that starts at time 0, level 1.0, then linearly interpolates to time 0.5 (half-way across the selection), level 1.0, then immediately jump down to level 0.0, and continue at 0.0 until time 1.0.This works, however the resulting waveform does not have a sharp one-sample transition (step) at time 0.5, instead it has a linear ramp between 1.0 and 0.0 over ~40 samples.

This is not acceptable in this situation.The conversion here suggests that within Audacity the Nyquist plugin actually runs at a control rate much less than the audio rate, hence the resulting ramp.I actually wish to create a much more complicated waveform than a square wave, so once this issue is resolved I can continue to construct the full waveform.My questions are:� is it possible to adjust the control rate to match the audio sampling rate, so that I can have ngquist control of the pwl function, and� how would this be incorporated into a Nyquist Lisp expression that also calls 'pwl' - I'm not very familiar with Lisp at all and don't understand how to execute two statements sequentially.

My guess is there's a function to do it.I would be happy to use Nyquist outside of Audacity if that makes more sense. The thread I linked to contained the answer I needed.

I'll post this ;rompt in case it helps someone in the future: (progv '(*control-srate*) (list *sound-srate*)(sum s (pwl0 10.5 10.5)))This sets the control rate equal to the sound sample rate, thereby allowing the pwl function to draw directly to the target level in a single sample.Also, it appears that statements in Lisp are made sequential by simply putting the next statement as the last parameter to the previous statement. For example, here the statement to call 'sum' is within a block that is the third parameter to progv.

Is that correct and general? No, only within some forms. These are (typically) pprompt ones that start with prog (like progv, prog1, prog2, progn and prog) and the ones that are said to have "an implicit progn" ( let, when, unless and friends).� Vatine Apr 17 '13 at 13:40 Oure sequence, relying on side-effects: (progn (do-thing-1) (do-thing-2) (do-thing-3) . (do-thing-n)) Sequencing, using returning values: (use-value-n (.

(use-value-3 (use-value-2 (produce-value))) .)� Vatine Apr 23 '13 at 10:46 discardBy posting your answer, you agree to the privacy policy and terms of service.Not the answer you're looking for? Browse other questions tagged lisp waveform piecewise audacity nyquist or ask your own question. TechnologyLife / ArtsCulture / RecreationScienceOther� Stack Overflow� Server Fault� Super User� Web Applications� Ask Ubuntu� Webmasters� Game Development� TeX - LaTeX� Programmers� Unix & Linux� Ask Different (Apple)� WordPress Development� Geographic Information Systems� Electrical Engineering� Android Enthusiasts� Information Security� Database Administrators� Drupal Answers� SharePoint� User Experience� Mathematica� Salesforce� ExpressionEngine� Answers� Cryptography� Code Review� Magento� Signal Processing� Raspberry Pi� Programming Puzzles & Code Golf�more (7)� Photography� Science Fiction & Fantasy� Graphic Design� Movies & TV� Music: Practice & Theory� Wudacity Advice (cooking)� Home Improvement� Personal Finance & Money� Academia�more (8)� English Language & Usage� Skeptics� Mi Yodeya (Judaism)� Travel� Christianity� English Language Learners� Japanese Language� Arqade (gaming)� Bicycles� Role-playing Games� Anime & Manga�more (18)� Mathematics� Cross Validated (stats)� Theoretical Computer Science� Physics� MathOverflow� Chemistry� Biology� Computer Science� Philosophy�more (3)� Stack Apps� Meta Propmt Exchange� Area 51� Stack Overflow Careers Nyquist Prompt lets you run and debug code snippets for your own plug-ins created using the Nyquist programming language.

See Nyquist Plug-ins Reference - Auadcity Wiki for more information about writing Nyquist code. To use Nyquist Prompt, first select some audio.

If the code you want to test generates audio, you can avoid the initial steps of preparing an audio selection by installing the Nyquist Generate Prompt plug-in instead.Accessed by: Effect > Nyquist Prompt.

Enter Nyquist CommandType the command as required. Enter on the keyboard moves the cursor to a new line. The code is lost after quitting Audacity, so you may want to copy any valuable code before quit.Use legacy (version 3) syntaxWhen selected, commands entered in the main text window will be interpreted as the "version 3" code.When not selected (default), commands entered in the main text window will be interpreted as "version 4" code.Version 4 code includes a number of variables that are not available in version 3.

In particular, the S variable is no longer used to pass sound from Audacity to Nyquist. In version 4 the S variable has been replaced by *TRACK*. Full details about the difference between version 3 and version 4 code can be found in the Audacity wiki Buttons� Preview: Pprompt what the code would sound like if applied.

As with preview in all effects, playback lasts for the length of preview specified in Playback Preferences. Plugin authors should use this button to test if a Preview button in their plug-in would accurately preview the effect as applied to the waveform.

Preview should not be used in effects that change over time (such as a fade effect) because Audacity's preview as currently implemented only applies the effect to the length of the previewed selection.� Debug: The Debug button works as it does in all Nyquist effects.

Clicking this button shows a progress dialog for processing the code, followed by an uneditable "Nyquist Output" window listing any errors or other output. Click OK to prmpt the output window and process the command, or use Enter on the keyboard. Hold Ctrl on Windows or Command on Mac before pressing Enter.� OK: Applies the code to the waveform selection without debug output.

Your entered code will be retained next time you open Nyquist Prompt in the Audacity session. Using the keyboard, hold Ctrl on Windows (or Command on Mac) then press Enter.� Cancel: No code is processed or debugged. Any code you entered after opening the window this time will be discarded. The Nyquist prompt supports both LISP syntax and SAL syntax. If the code you enter cannot be recognized as valid Nyquist code in either LISP or SAL syntax, an error message will appear with a hint about making a correction. Advanced users: An experimental "Nyquist Workbench" graphical editor module is available if you compile the module and Audacity from source code, then enable the module in Modules Preferences.Links|< Index of Effects, Generators and Analyzers|< Effect Menu This page explains how to use the Audacity Nyquist Prompt to test-run Nyquist code snippets using the SAL syntax.

For Audacity versions below 1.3.13 (Beta), SAL syntax is not peompt in the Nyquist Prompt. command, so you should use LISP syntax as described in Nyquist Basics: The Audacity Nyquist Prompt.The "Nyquist Basics" tutorials start with very simple examples at the top of each page with increasing complexity towards the end.

You do not necessarily need to work through to the end of each page to be promph to understand the other tutorials. If you feel confused, try any of the other Nyquist Basics tutorials, in any order. Every "Basics" page contains lots of notes and hints where you can find extra information.Related article(s):� Digital Audio Technology� Nyquist Audio Programming� Nyquist 3.02 Reference Manual - the latest Nyquist Manual (mostly using SAL syntax)� Nyquist 2.37 Reference Manual - the latest version entirely using LISP syntax Contents� 1 Setting up� 1.1 Load a Sound File� 1.2 Create a Mono Track� 1.3 Create a Stereo Track� 2 The Nyquist Prompt� 2.1 The Nyquist Interpreter� 2.2 The Nyquist Debugger� 2.3 Basic Nyquist Commands� 2.4 Simple Examples� 2.4.1 Applying a DC offset to a signal� 2.4.2 Modulating with a carrier frequencySetting upMake sure you are using Audacity 1.3.13 or higher.

If not, please visit Nyquist Basics: The Audacity Nyquist Prompt.The Audacity Nyquist prompt appears in Audacity's Effect menu, which is activated only if an Audacity audio track exists and at least some audio in it is selected. For testing generate commands in Nyquist, you can addNyquist Generate Prompt to the Audacity "Plug-Ins" folder. Load a Sound FileSound files are imported into Audacity via:File > Import > Audio or the shortcut CTRL + SHIFT + IIf you have no pre-existing sound files to work with, you can create your own mono or stereo tracks via the Audacity Generate menu.Create a Mono TrackClick Generate > Tone.

Leave everything as-is and just click "OK". A mono track will appear in the Audacity window:Create a Stereo Track1. Create an empty stereo track. Click Track > Promph New. > Stereo Track.An empty stereo track will appear in the Audacity window.2. Now click Generate > Tone. Leave everything as-is and just click "OK".

The stereo tracks will become filled with the generated sound.The Audacuty PromptSelect the track(s) and click Effect > Nyquist Prompt. Effects are not activated until at least a portion of the track(s) have been selected. You can select all tracks by pressing CTRL + A on the keyboard.The Nyquist Prompt appears like this:The Nyquist InterpreterIn the Nyquist Prompt window, typereturn "hello"into the text field as follows:When you click OK, you should get a message box displaying the word hello:The message box disappears when you click "OK".This, as you have learned, is how you can send messages to the user.The Nyquist DebuggerAfter clicking OK in the "hello" message box, go back to Effect > Nyquist Prompt, and this time, typereturn hellothis time leaving off the quotes around "hello":Important: This time, click "Debug" instead of "OK".You should first get a window displaying a "Nyquist did not return audio" or a similar message:After clicking "OK" in the window above, a second window appears, displaying the error messages that Nyquist returned.

Notice that there are two parts to the message. The first line says what went wrong. Here, HELLO is interpreted as a variable, but the variable has no value, which is an error. Starting with the second line is a "traceback" which tells where in the program the error occurred.

MAIN refers to any top-level command. If you defined a function and the error occurred within the function, this would be indicated in the traceback. NOTE: Nyquis "Nyquist output" window only appears if you click "Debug" in the "Nyquist Prompt" window.

If you click "OK", then, even with a Nyquist error, only the first window will appear. Basic Nyquist CommandsThe current Nyquist manual introducing SAL syntax is here: Nyquist 3.02 Reference Manual.Audacity uses the 's' variable to reference the current audio file/selection. Thus, you can use basic commands such as 'mult' or 'sum' with 's' and the Nyquist prompt will replace the file/selection with the result (or as Audacity calls it, "returned audio").Simple Examples NOTE: These examples are focused upon using Audacity to manipulate digital signals (clearly Audacity is better suited to audio, but features such as Nyquist can open many other uses).For those interested, the signal used is an infra red (IR) sample from a remote control. NOTE: Each code example will be shown once using SAL syntax, and again using LISP syntax.

Either form can be used, but never try to mix them in a single program or prompt! Applying a DC offset to a signalOriginal Signal before command.Type the following into the Nyquist Prompt (using SAL syntax):return s + 1Or type the following equivalent LISP command:(sum s 1)The whole signal has now movMy friend Flavio and I record a Spanish-language podcast dedicated to Apple products called Puromac. Since he currently lives in Puerto Rico and I'm in New York City, we talk over Skype and record the conversation using either Audio Hijack Pro or Call Recorder for Skype.In our most recent episode, Flavio's mic produced an audible 60hz hum throughout the whole podcast.

When he ran the audio file through Levelator (an excellent utility to adjust the levels of all audio within a file) the hum was made even louder. Before doing any post work on the audio file, I needed to remove the hum.I use Audacity for my audio editing and while it has a very good Noise Removal tool, it was failing to pull out the hum completely, leaving a "thumping" effect over the audio.

My guess is that the harmonics of the electrical hum (the frequency isn't a solid 60hz) were a problem for the Noise Removal tool.What I needed was a notch filter-a filter that removes a specific frequency from an audio signal. My plan was to use a notch filter to remove audqcity bulk of the hum and then clean up the rest using Audacity's Noise Removal tool.Searching around the web, I found a Nyquist script that removed a 60hz hum along with an additional 4 of its harmonics.Audio samples (You will need headphones to hear the differences):� Original audio file with a noticeable hum.� An attempt to remove the hum using solely Audacity's Noise Removal tool.

You will notice there is still a hum in parts of the dialogue which fades in and promp The stereo Nyquist script below applied to the original file.� The stereo Nyquist script applied followed by Audacity's Audacity nyquist prompt Removal tool. What is Nyquist?Nyquist is a programming language for use in audio and music applications developed at Carnegie Mellon University (my alma matter).

Version 2.x of the language (which is what Audacity uses) is written in Lisp. Audacity's help page has a very brief but informative introduction into Lisp. I recommend reading it as it makes the Nyquist script below easier to understand. You can also byquist the Nyquist page at CMU for more audaciry a 60hz hum with a Nyquist script:Audacity doesn't have a full Nyquist development environment, but it does have a plugin that allows you enter a Nyquist script to run and debug.In Audacity, select a portion of the audio you want to clean.

(You could select the whole thing, pronpt since there is no preview function nquist Nyquist scripts, and my audio was more than a hour long, I selected a representative portion of the audio, ran the script, made sure it worked, pressed Command-Z (on a Mac) to undo the script, selected the whole file then ran the script again.

)If you're working with a mono audio tractk, select Effect:Nyquist Prompt. then in the window that pops up, propmt the following script.(notch2(notch2(notch2(notch2(notch2s300 10)240 8)180 audacjty 2)60 1). Then click "OK".This runs audacityy recursive set of notch filters (the notch2 function) on the audio signal, filtering out 60, 120, 180, 240 and 300 hz frequencies.For a stereo track, the script is more involved:(vector(notch2(notch2(notch2(notch2(notch2(aref s 0)300 10)240 8)180 nyquiet 2)60 1)(notch2(notch2(notch2(notch2(notch2(aref s 1)300 10)240 8)180 4)120 2)60 1) )This script is the same as the first, except that it handles 2 inputs via a vector (basically an array).If you still hear a little bit of hum (I did, though it was barely audible), use the Noise Removal filter in Audacity for that last bit of noise. Examining the Nyquist script:As I understand it, in Lisp everything is a function call.

The format for all calls is:([FUNC_NAME] [ARGS.])The notch2 function is called like this:(notch2 s 60 1)Where "notch2" is the name of the function, "s" is the first promlt referring to the audio signal (I guess Audacity calls it "s" and makes it available globally), "60" is the value in Hertz of the frequency to extract and "1" is the Q factor.The Nyquist and Audacity documentation don't talk much about what a Q factor is, except that it's the "depth and width" of the function, or the "fudge factor" around the frequency.

My friend Taylor sent me this Wikipedia article on Q factors after seeing the original version of this blog posts in which I conceded ignorance on the subject. Essentially, a value below 1 creates a wider notch, while a value above nyquidt creates a narrower one.The script above could be written as:(notch2 (notch2 (notch2 (notch2 (notch2 s 300 10) 240 8) 180 4) 120 2) 60 1)Though it's a little harder auudacity read, you audacity nyquist prompt a better sense of the recursive nature of the call.

The inner notch2 function call filters out 300hz with the signal "s" as the input. The output of that call is fed byquist the second notch2 call, which filters out 240hz. Then comes 180hz, 120hz and finally the outer call filters out the remaining 60hz signal from the audio.You can read more about noise removal in Audacity on its Wiki page. Prebuilt Nyquist filters:After writing this blog entry I discovered that AudacityThe Audacity Nyquist PromptAudacity Support Forum /Audacity and Nyquist /Nyquist Reference Manual /Nyquist Examples and TutorialsSteven Jones /Pedro Morales /David Sky /Nyquist and Emacs /Audacity WikiThe Audacity Nyquist PromptWith the Audacity Nyquist Prompt you can test small snippets of Nyquistcode or doing quick audio hacks.

On this page the basic usage of the Nyquistprompt is explained.� Preparations� Load a Sound File� Create a Mono Track� Create a Stereo Track� The Nyquist Prompt� The Nyquist Interpreter� The Nyquist DebuggerNote: All [comments] and [explanations] are written in squarebrackets, so they cannot be confused with (Lisp code).1 PreparationsThe Audacity Nyquist prompt is placed in the Audacity 'Effect' menuwhich only can be activated if an Audacity audio track exists and at least apart of it marked or selected [Audacity 1.3.4].Back to top1.1 Load a Sound FileIf you have a mono or stereo sound file available you can load itinto Audacity via:Audacity File menu > Import >Audio or Shift + Control +IIf you have no sound files available you can build yourown mono or stereo tracks via the Audacity 'Generate' menu.Back to top1.2 Create a Mono Track1.

Go to the Audacity 'Generate' menu and choose 'Tone'. Leaveeverything as-is, just click 'OK', a mono track will appear in the Audacitywindow.Back to top1.3 Create a Stereo Track1.

Mark the whole mono track from above either by pressing'Ctrl+A' on the keyboard, or by clicking with the mouse into the trackheader, with taking care not to move the buttons or sliders, the whole trackthen will appear in a different color.2. Go to the 'Edit' menu and choose 'Duplicate'. A second,identical mono pfompt will appear below the first one.3.

In the upper mono track, open the track menu by clicking on thesmall black triangle at the top of the track header and coose 'Make stereotrack'.

Both mono tracks then will get combined to a single stereotrack.Back to top2 The Nyquist PromptTo enable the Audacity 'Effect' menu at least a part of an Audacity audiotrack must be marked or selected. Then go to the Audacity 'Effect' menu andchoose 'Nyquist prompt'.

A window like the following will appear:Back to top2.1 The Nyquist InterpreterIn the 'Nyquist Prompt' window, type into the text field a string"hello" with quotes:If you click 'OK', you should get audacoty window displaying 'hello':Click 'OK' in the 'hello' window to make it disappear again.Congratulations, you just have learned how to send text messages to theuser.Back to top2.2 The Nyquist DebuggerAfter clicking 'OK' in the 'hello' window, go back to the Audacity'Effect' menu and choose 'Nyquist prompt' again, but this time typehello without the quotes:Important: Now click 'Debug' instead of 'OK'.You should first get a window displaying a 'Nyquist did not return audio'or similar message:After clicking 'OK' pro,pt the window above, a second window appears,displaying the detailed Nyquist error messages:Important: The 'Nyquist output' window only appears if you click'Debug' in the 'Nyquist Prompt' window.

If you click 'OK', then, even with aNyquist error, only the first window will appear.Back to topSteven Jones /Pedro Morales /David Sky /Nyquist and Emacs /Audacity WikiAudacity Support Forum /Audacity and Nyquist /Nyquist Reference Manual /Nyquist Examples and Tutorials This page explains how to use the Audacity Nyquist Prompt to test-run Nyquist code snippets.The "Nyquist Basics" tutorials start with very simple examples at the top of each page with increasing complexity towards the end.

You do not necessarily need to work through to the end of each page to be able to understand the other tutorials. If you feel confused, try any of the other Nyquist Basics tutorials, in any order. Every "Basics" page contains lots of notes and hints where you can find extra information.Related article(s):� Digital Audio Technology� Nyquist Audio Programming� Nyquist 3.02 Reference Manual - the latest Nyquist Manual (mostly using SAL syntax)� Nyquist 2.37 Reference Manual - the latest version entirely using LISP syntax Contents� 1 Setting up� 1.1 Load a Sound File� 1.2 Create a Mono Track� 1.3 Create a Stereo Track� 2 The Nyquist Prompt� 2.1 The Nyquist Interpreter� 2.2 The Nyquist Debugger� 2.3 Basic Nyquist Commands� 2.4 Simple Examples� 2.4.1 Applying a DC offset to a signal� 2.4.2 Modulating with a carrier frequencySetting upMake sure you have a version of Audacity that is 1.3.12 (Beta) or older.

Otherwise, please see Nyquist Basics: The Audacity Nyquist Prompt With SAL.The Audacity Nyquist prompt appears in Audacity's "Effect" menu, which is activated only if an Audacity audio track exists and at least some audio in it is selected. For testing generate commands in Nyquist, you can addNyquist Generate Prompt to the Audacity "Plug-Ins" folder. Load a Sound FileSound files are imported into Audacity via:File > Import > Audio or the shortcut CTRL + SHIFT + IIf you have no pre-existing sound files to work with, you can create your own mono or stereo tracks via the Audacity "Generate" menu.Create a Mono TrackClick Generate > Tone.

Leave everything as-is and just click "OK". A mono track will appear in the Audacity window:Create a Stereo Track1. Create an ausacity stereo track.� In Audacity 1.2.x, click Project > New Stereo Track.� In Audacity 1.3.x-beta, click Track > Add New. > Stereo Track.An empty stereo track will appear in the Audacity window.2. Now click Generate > Tone. Leave everything as-is and just click "OK". The stereo tracks will become filled with the generated sound.The Nyquist PromptSelect the track(s) and click Effect > Nyquist Prompt.

Effects are not activated until at least a portion of the track(s) have been selected. You can select all tracks by pressing CTRL + A on the keyboard.The Nyquist Prompt appears like this:The Nyquist InterpreterIn the Nyquist Prompt window, type (print "hello") into the text field with the parentheses and quotes, as follows: NOTE: The Nyquist Prompt must see an open parenthesis as the first non-space character; otherwise it will assume this is written using SAL syntax.

Otherwise, we might have just typed "hello", which worked in earlier versions of Audacity.When you click OK, you should get a message box displaying the word hello:The message box disappears when you click OK.This, as you have learned, is how you can send messages to the user.The Nyquist DebuggerAfter clicking OK in the "hello" message box, go back to Effect > Nyquist Prompt, and this time, type (print hello) with the parentheses but without the quotes:Important: This time, click "Debug" instead of "OK".You should first get a window displaying a "Nyquist did not return audio" or a similar message:After clicking OK in the window above, a second window appears, displaying the error messages that Nyquist returned: NOTE: The "Nyquist output" window only appears if you click "Debug" in the "Nyquist Prompt" window.

If you click "OK", then, even with a Nyquist error, only the first window auxacity appear.Basic Nyquist CommandsThe Nyquist manual entirely using LISP syntax is here: Nyquist Reference Manual.The current Nyquist manual introducing SAL syntax is here: Pronpt 3.02 Reference Manual.Audacity uses the 's' variable to reference the current audio file/selection.

Thus, you can use basic commands such as 'mult' or 'sum' with 's' and the Nyquist prompt will replace the file/selection with the result (or as Audacity calls it, "returned audio").Simple Examples NOTE: These examples are focused upon using Audacity to manipulate digital signals (clearly Audacity is better suited to audio, but features such as Nyquist can open many other uses).For those interested, the signal used is an infra red (IR) sample from a remote control. NOTE: Each nyquust example will be shown once using LISP syntax, and again using SAL syntax.

Either form can be used, but never try to mix them in a single program or prompt! Prior to Audacity Version 1.3.13 (Beta), only LISP syntax works.

Applying a DC offset to a signalOriginal Signal before command.Type the following into the Nyquist Prompt (using LISP syntax):(sum s 1)Or type the following equivalent SAL command:return s + 1The whole signal has now moved up to above zero.Modulating with a carrier frequencyTo multiply a signal with a generated carrier signal, you canThis page explains how to use the Audacity Nyquist Prompt to test-run Nyquist code snippets.The "Nyquist Basics" tutorials start with very simple examples at the top of each page with increasing complexity towards the end.

You do not necessarily need to work through to the end of each page to be able to understand the other tutorials. If you feel confused, try any of the other Nyquist Basics tutorials, in any order. Every "Basics" page contains lots of notes and hints where you can find extra information.Related article(s):� Digital Audio Technology� Nyquist Audio Programming� Nyquist 3.02 Reference Manual - the latest Ngquist Manual (mostly using SAL syntax)� Nyquist 2.37 Reference Manual - the latest pprompt entirely using LISP syntax Contents� 1 Setting up� 1.1 Load a Sound File� 1.2 Create a Mono Track� 1.3 Create a Stereo Track� 2 The Nyquist Prompt� 2.1 The Nyquist Interpreter� 2.2 The Nyquist Debugger� 2.3 Basic Nyquist Commands� 2.4 Simple Examples� 2.4.1 Applying a DC offset to a signal� 2.4.2 Modulating with a carrier frequencySetting upMake sure you have a version of Audacity that is 1.3.12 (Beta) or older.

Otherwise, please see Nyquist Basics: The Audacity Nyquist Prompt With SAL.The Audacity Nyquist prompt appears in Audacity's "Effect" menu, which is activated only if an Audacity audio prompr exists and at least some audio in it is audacith testing generate commands in Nyquist, you can addNyquist Generate Prompt to the Audacity "Plug-Ins" folder. Load a Sound FileSound files are imported into Audacity via:File > Import > Audio or the shortcut CTRL + SHIFT + IIf you have no pre-existing sound files to work with, you can create your own mono or stereo tracks via the Audacity "Generate" menu.Create a Mono TrackClick Generate > Tone.

Leave everything as-is and just click "OK". A mono track will appear in the Audacity window:Create a Stereo Track1. Create an nyquost stereo track.� In Audacity 1.2.x, click Project > New Stereo Track.� In Prompg 1.3.x-beta, click Track > Add New. > Stereo Track.An empty stereo track will appear in the Audacity window.2.

Now click Generate > Tone. Leave everything as-is and just click "OK". The stereo tracks will become filled with the generated sound.The Nyquist PromptSelect the track(s) and click Effect > Nyquist Prompt. Effects are not activated until at least a portion of the track(s) have been selected.

You can select all tracks by pressing CTRL + A on the keyboard.The Nyquist Prompt appears like this:The Nyquist InterpreterIn the Nyquist Prompt window, type (print "hello") into the text field with the parentheses and quotes, as follows: NOTE: The Nyquist Prompt must see an open parenthesis as the first non-space character; otherwise aueacity will assume this is written using SAL syntax.

Otherwise, we might have just typed "hello", which worked in earlier versions of Audacity.When you click OK, you should get a message box displaying the word hello:The message box disappears when you click OK.This, as you have learned, is how you can send messages to the user.The Nyquist DebuggerAfter clicking OK in the "hello" message box, go back to Effect > Nyquist Prompt, and this time, type (print hello) with the parentheses but without the quotes:Important: This time, click "Debug" instead of "OK".You should first get a window displaying a "Nyquist did not return audio" or a similar message:After clicking OK in the window above, a second window appears, displaying the error messages that Nyquist returned: NOTE: The "Nyquist output" window only appears if you click "Debug" in the "Nyquist Prompt" window.

If you click "OK", then, even with a Nyquist error, only the first window will appear.Basic Nyquist CommandsThe Nyquist manual entirely using LISP syntax is here: Nyquist Reference Manual.The current Nyquist manual introducing SAL syntax is here: Nyquist 3.02 Reference Manual.Audacity uses the 's' variable to reference the current audio file/selection. Thus, you can use basic commands such as 'mult' or 'sum' with 's' and the Nyquist prompt will replace the file/selection with the result (or as Audacity calls it, "returned audio").Simple Examples NOTE: These examples are focused upon using Audacity to manipulate digital signals (clearly Audacity is better suited aueacity audio, but features such as Nyquist can open many other uses).For those interested, the signal used is an infra red (IR) sample from a remote control. NOTE: Each code example will be shown once using LISP syntax, and again using SAL syntax.

Either form can be used, but never try to mix them in a single program or audwcity Prior to Audacity Version 1.3.13 (Beta), only LISP syntax works. Applying a DC offset to a signalOriginal Signal before command.Type the following into the Nyquist Prompt (using LISP syntax):(sum s 1)Or type the following equivalent SAL command:return s + 1The whole signal has now moved up to above zero.Modulating with a carrier frequencyTo multiply a signal with a generated carrier signal, you can�TourStart here for a quick overview of the site�Help CenterDetailed answers to any questions you might have�MetaDiscuss the workings and policies of this site�About UsLearn more about Stack Overflow the company�BusinessLearn more about hiring developers or posting ads with us Announcing Stack Overflow DocumentationWe started with Q&A.

Technical documentation is next, and we need your help.Whether you're a beginner or an experienced developer, you can contribute.Sign up and start helping >Learn more about Documentation > I wish to use the Nyquist Prompt plugin in Audacity to construct a piece-wise linear waveform of 2048 samples in length.

For example, I can generate a square pulse wave by starting with 2048 silent (zero) samples, selecting all, and then invoking the Nyquist Prompt with: (sum s (pwl0 10.5 10.5))This uses the piece-wise linear (pwl) function to create a waveform that starts at time 0, level 1.0, then linearly interpolates to time 0.5 (half-way across the selection), level 1.0, then immediately jump down to level 0.0, and continue at 0.0 until time 1.0.This works, however the resulting waveform does not have promph sharp one-sample transition (step) at time 0.5, instead it has a linear ramp between 1.0 and 0.0 over ~40 samples.

This is not acceptable in this situation.The conversion here suggests that within Audacity the Nyquist plugin actually runs at a control rate much less than the prrompt rate, hence the resulting ramp.I actually wish to create a much more complicated waveform than a square wave, so once this issue is resolved I can continue to construct the full waveform.My questions are:� is it possible to adjust the control rate to match the audio sampling rate, so that I can have sample-accurate control of the pwl audacitu, and� how would this be incorporated into a Nyquist Lisp expression that also calls 'pwl' - I'm not very familiar with Lisp at all and don't understand how to execute two statements sequentially.

My guess is there's a function to do it.I would be happy to use Nyquist outside of Audacity if that makes more sense. The thread I linked to contained the answer I needed. I'll post this here in case it helps someone in the future: (progv '(*control-srate*) (list *sound-srate*)(sum s (pwl0 10.5 10.5)))This sets the control rate equal pdompt the sound sample rate, thereby allowing the pwl function to draw directly to the target level in a single sample.Also, it appears that statements in Lisp are made sequential by simply putting the next statement as the last parameter to the previous statement.

For example, here the statement to call 'sum' is within a block that is the third parameter to progv. Is that correct and general? No, only within some forms. These are (typically) the ones that start with prog (like progv, prog1, prog2, progn and prog) and the ones that are said to have "an implicit progn" ( let, when, unless and friends).� Vatine Apr 17 '13 at 13:40 Oure sequence, relying on side-effects: (progn (do-thing-1) (do-thing-2) (do-thing-3) .

(do-thing-n)) Sequencing, using returning values: (use-value-n (. (use-value-3 (use-value-2 (produce-value))) .)� Vatine Apr 23 '13 at 10:46 discardBy posting your answer, you agree to the privacy policy and terms of service.Not the answer you're looking for? Browse other questions tagged lisp waveform piecewise audacity nyquist or ask your own question. TechnologyLife / ArtsCulture / RecreationScienceOther� Stack Overflow� Server Fault� Super User� Web Applications� Ask Ubuntu� Webmasters� Game Development� TeX - LaTeX� Programmers� Unix & Linux� Ask Different (Apple)� WordPress Development� Geographic Information Systems� Electrical Engineering� Android Enthusiasts� Information Security� Database Administrators� Drupal Answers� SharePoint� User Experience� Mathematica� Salesforce� ExpressionEngine� Answers� Cryptography� Code Review� Magento� Signal Processing� Raspberry Pi� Programming Puzzles & Code Golf�more (7)� Photography� Science Fiction & Fantasy� Graphic Nyauist Movies & TV� Music: Practice & Theory� Seasoned Advice (cooking)� Home Improvement� Personal Finance & Money� Academia�more (8)� English Language & Usage� Skeptics� Mi Yodeya (Judaism)� Travel� Christianity� English Language Learners� Japanese Language� Arqade (gaming)� Bicycles� Role-playing Games� Anime & Manga�more (18)� Mathematics� Cross Validated (stats)� Theoretical Computer Science� Physics� MathOverflow� Chemistry� Biology� Computer Science� Philosophy�more (3)� Stack Apps� Meta Stack Exchange� Area aduacity Stack Overflow Careers This page explains how to use the Audacity Nyquist Prompt to test-run Nyquist code snippets using the SAL syntax.

For Audacity versions below 1.3.13 (Beta), SAL syntax is not supported in the Nyquist Prompt. command, so you should use LISP syntax as described in Nyquist Basics: The Audacity Nyquist Prompt.The "Nyquist Basics" tutorials start with very simple examples at the top of each page with increasing complexity towards the end.

You do not necessarily need to work through to the end of each page to be able to understand the other tutorials. If you feel orompt, try any of the other Nyquist Basics tutorials, in any order.

Every "Basics" page contains lots of notes and hints where you can find extra information.Related article(s):� Digital Audio Technology� Nyquist Audio Programming� Nyquist 3.02 Reference Manual - the latest Nyquist Manual (mostly using SAL syntax)� Nyquist 2.37 Reference Manual - the latest version audacitj using LISP syntax Contents� 1 Setting up� 1.1 Load a Sound File� 1.2 Create a Mono Track� 1.3 Create a Stereo Track� 2 The Nyquist Prompt� 2.1 The Nyquist Interpreter� 2.2 The Nyquist Debugger� 2.3 Basic Nyquist Commands� 2.4 Simple Examples� 2.4.1 Applying a DC offset to a signal� 2.4.2 Modulating with a carrier frequencySetting upMake sure you are using Audacity 1.3.13 or higher.

If not, please visit Nyquist Basics: The Audacity Nyquist Prompt.The Audacity Nyquist prompt appears in Audacity's Effect menu, which is activated only if an Audacity audio track exists and at least some audio in it is selected. For testing generate commands in Nyquist, you can addNyquist Generate Prompt to the Audacity "Plug-Ins" folder. Load a Sound FileSound files are imported into Audacity via:File > Import > Audio or the shortcut CTRL + SHIFT + IIf you have no pre-existing sound projpt to work with, you can create your own mono or stereo tracks via the Audacity Generate menu.Create a Mono TrackClick Generate > Tone.

Leave everything as-is and just click "OK". Propt mono track will appear in the Audacity window:Create a Stereo Track1. Create an empty stereo track. Click Track > Add New.

> Stereo Track.An empty stereo track will appear in the Audacity window.2. Now click Generate > Tone. Leave everything as-is and just click "OK". The stereo tracks will become filled nyquizt the generated sound.The Nyquist PromptSelect audacitty track(s) and click Effect > Nyquist Prompt.

Effects are not activated until at least a portion of the track(s) have been selected. You can select all tracks by pressing CTRL + A on the keyboard.The Nyquist Prompt appears like this:The Nyquist InterpreterIn the Nyquist Prompt window, typereturn "hello"into the text field as follows:When you click OK, you should get a message box displaying the word hello:The message box disappears when you click "OK".This, as you have learned, is how you can send messages to the user.The Nyquist DebuggerAfter clicking OK in the "hello" message box, go back to Effect primpt Nyquist Prompt, and this time, typereturn hellothis time leaving off the quotes around "hello":Important: This time, click "Debug" instead of "OK".You should first get a window displaying a "Nyquist did not return audio" or a similar message:After clicking "OK" in the window above, a second window appears, displaying the error messages that Nyquist returned.

Notice that there are two parts to the message. The first line says what went wrong. Here, HELLO is interpreted as a variable, but the variable has no value, which is an error. Starting with the second line is a "traceback" which tells where in the program the error occurred. MAIN refers to any top-level command. If you defined a function and the error occurred within the function, this would be indicated in the traceback. NOTE: The "Nyquist output" window only appears if you click "Debug" in the "Nyquist Prompt" window.

If you click "OK", then, even with a Nyquist error, only the first window will appear. Basic Nyquist CommandsThe current Nyquist manual introducing SAL syntax is here: Nyquist 3.02 Reference Manual.Audacity uses the 's' variable to reference the current audio file/selection. Thus, you can use basic commands such as 'mult' or 'sum' with 's' and the Nyquist prompt will replace the file/selection with the result (or as Audacity calls it, "returned audio").Simple Examples NOTE: These examples are focused upon using Audacity to manipulate digital signals (clearly Audacity is better suited to audio, but features such as Nyquist can open many other uses).For those interested, the signal used is an infra red (IR) sample from a remote control. NOTE: Each code example will be shown once using SAL syntax, and again using LISP syntax.

Either form can be used, but never try to mix them in a single program or prompt! Applying a DC offset to a signalOriginal Signal before command.Type the following into the Nyquist Prompt (using SAL syntax):return s + 1Or type the following equivalent LISP command:(sum s 1)The whole signal has now movThis page is a list of suggested "how-to" and explanatory articles for Nyquist programmers. Nyquist is a Audqcity programming language for audio synthesis and analysis nyqust by Roger B.Dannenberg.

A number of effects and analysis tools shipped with Audacity are written in Nyquist. Audacity interfaces to Nyquist using the somewhat stripped-down and modified Libnyquist library.Many articles herein are still to be written.

Feel free to request other topics by clicking the discussion tab at the top of this page. If you are looking for extra Nyquist plug-ins to use, see Nyquist Plugins.Related article(s):� Nyquist homepage at Carnegie Mellon University� Nyquist Plugins Reference - an overview of plug-in structure and syntax� Other pages in our Digital Audio Technology category Contents� 1 Basic Experiments� 2 Advanced topics� 3 Very advanced topicsBasic ExperimentsExperiments from the Audacity Nyquist prompt:� The Audacity Nyquist Prompt - how it works� Changing the Volume - in different ways� Changing the volume of an Audacity audio track� Changing the Volume of the left and right stereo channels independently� Changing the volume with envelopes - fade in, fade out, etc.� Changing the volume with a low frequency generator - audaxity effect� Increasing/decreasing treble and bass - simple equalizer� Simple delay effect� Audio loops with Nyquist - simple loop and echo effects.Advanced topics� Narrowing and widening stereo signals� Removing vocals from a stereo recording� Writing your own Audacity Nyquist plug-ins� Official Audacity Nyquist plug-in documentation� Updated plug-in information, 2007� Nyquist 3.02 Reference Manual - the latest Nyquist manual, most functions described in terms of SAL syntax� Nyquist 2.37 Reference Manual - the latest Nyquist manual using all LISP syntax� XLISP documents collection - XLISP is the programming language Nyquist is based on Please note: The notation in the current Nyquist 3.02 Reference Manual from the links above emphasizes SAL syntax, although the underlying functions are the same.

SAL only works in Audacity 1.3.8 or later.Use the Nyquist 2.37 Manual from the links above if you would like to see functions described using LISP syntax. These work in any Audacity version. We are currently working on unifying the old Nyquist plug-in documentation on the main Audacity website and the updated information in the German forum into one single place here in the Wiki.

The outdated list of Nyquist plug-ins at http://web.audacityteam.org/download/nyquistplug-ins has audacuty been removed. The only disadvantage of this is that the potential (unused) audaciry for translating the plug-ins list is lost.

Translating the list was never a priority as the plug-ins themselves are in English. Possibly we could in time add (at least, German) translations of Wiki Nyquist pages, or even links to German versions of these plug-ins?Very advanced topics� Multiple echoes with different delay times - reverb effect� The relations between timeshift and frequency response� Frequency-dependent delays with comb and allpass filters - reverb, chorus, phaser, etc.� Dynamics processing - how to nyqjist control signals from volume behaviour� Auto-equalizing - how to derive control signals from frequency behaviour Nyquist Prompt lets you run and debug code snippets for your own plug-ins created using the Nyquist programming language.

See Nyquist Plug-ins Reference - Audacity Wiki for more information about writing Nyquist code. To use Nyquist Prompt, first select some audio. If the code you want to test generates audio, you can avoid the initial steps of preparing an audio selection by installing the Nyquist Generate Prompt plug-in instead.Accessed by: Effect > Nyquist Prompt.

Enter Nyquist CommandType the command as required. Enter on the keyboard moves the cursor to a new line. The code is lost after quitting Audacity, so you may want to copy any valuable code before ynquist legacy (version 3) syntaxWhen selected, commands entered in the main text window will be interpreted as the "version 3" code.When not selected (default), commands entered in the main text window will be interpreted as "version 4" code.Version 4 code includes a number of variables that are not available in version 3.

In particular, the S variable is no longer used to pass sound from Audacity to Nyquist. In version 4 the S variable has been replaced by *TRACK*. Full details about the difference between version aufacity and version 4 code can be found in the Audacity wiki Buttons� Preview: Previews what the code would sound audacitj if applied.

As with preview in all effects, playback lasts for the length of preview specified in Playback Preferences. Plugin authors should use this button to test if a Preview button in their plug-in would accurately preview the effect as applied to the waveform. Preview should not be used in effects that change over time (such as a fade effect) because Audacity's preview as currently implemented only applies the effect to the length of the previewed selection.� Debug: The Debug button works as it does in all Nyquist effects.

Clicking this audacihy shows a progress dialog for processing the code, followed njquist an uneditable "Nyquist Output" window listing any errors or other output. Click OK to close the output window and process the command, or use Enter on the keyboard. Hold Ctrl on Windows or Command on Mac before pressing Enter.� OK: Applies the code to the waveform selection without debug output.

Your entered code will be retained next time you open Nyquist Prompt in the Audacity session. Using the keyboard, hold Ctrl on Windows (or Command on Mac) then press Enter.� Cancel: No code is processed or debugged. Any code you entered after opening the window this time will be discarded. The Nyquist prompt supports both LISP syntax and SAL syntax. If the code you enter cannot be recognized as valid Nyquist code in either LISP or SAL syntax, an error nyquits will appear with a hint about making a correction. Advanced users: An experimental "Nyquist Workbench" graphical editor module is available if you compile the module and Audacity from source code, then enable the module in Modules Preferences.Links|< Index of Effects, Generators and Analyzers|< Effect Menu