Index of Effects, Generators and Analyzers

Peter 20Jun12: "Decision" moved here from the ToDo Page:

• We're not documenting all effects or all analyze menu items on a page-of their own. Only the most complex ones that require a screenshot will get that treatment. We don't have the time to do them all. Most effects and most analyze menu items will appear on the relevant page about that menu.

Gale 17Sep12: ToDo-2 Surely though if this is an "Index" page it should include all shipped effects? Phaser, Repeat and Reverse are missing (I can see no case to omit Phaser in this list).
Ed 3Nov12 +1 for all shipped effects being listed.

• Peter 4Nov12: +1 for all shipped effects to be listed.

Ed 3Nov12 In the title we make a semantic difference between "Effects, Generators and Analyzers" then we go on to have a section titles "Alphabetical Index of Effects" in which we mix "effects", "generators" and "analyzers" hodge-podge in the index table then somewhat sorted in the "by function" section but with no (obvious to me) rhyme nor reason to the sort method (and certainly no explanation as to how they are sorted for the reader). I do like them sorted by function but think it needs a quick-and-dirty index to the function groups--e.g. move the TOC below the "Effects By Function" (which BTW should read something like: "Effect, Generators and Analyzers By Function") and eliminated the #1 item and have only the #2 & 2.n items. Since these are all formatted as bulleted lists they should also follow Connie on lists (lots of trivial work to make it so).
Ed 3Nov12 Any E, G or A which has no homepage should be carefully reviewed to ensure that the current text is adequate (there are some which I find way too uninformative).

• Peter 4Nov12: I agree with Ed's comment that the text for any which have no home page should be reviewed for adequacy. Personally I think I'd prefer to see each and every E,G & A have a "homepage".
  • Peter 5Nov12: I note that on Effect Menu we seem to have a fuller list (possibly a complete list?).

This page is a quick index to Audacity's Effects, Generators and Analysis tools:

• An Effect changes the audio is some way.
• A Generator creates new audio, either in an existing track or in a new track.
• An Analyze tool performs analysis on a selection of audio - it does not change the audio and does not create new audio.

Although by default, no keyboard shortcuts are provided for most Effect, Generate or Analyze commands, it is possible to set up your own shortcut for any of these commands. For instructions on how to do this please see Keyboard Preferences.

Alphabetical Index of Effects

Gale 03Nov12: Two users have complained already about the change in ordering in this table to crosswise instead of downwards (sigh). It's reordered downwards in this editornote.

When we've discussed before, I thought the consensus was for downwards ordering, especially if the point is that the table is alphabetical. Personally I find this makes for far easier reading. I cannot find any consensus about the "correct" ordering of a list table. I think that screen readers will read any table crosswise by default, so to counter that I have followed guidelines by adding a summary that states the table's layout. JAWS has a keystroke to read from a table cell downwards (http://www.freedomscientific.com/doccenter/archives/training/JAWSKeystrokes.htm).

And yes I know modifying the table is easier if read crosswise, but that's not really the point if people are beefing about it. I've got to vote for downwards ordering.

• Ed 3Nov12: +1 downward--it is very hard to read otherwise.
• Peter 4Nov12: +1 for downward - I find it much easier and quicker to read and to locate entries that way.
• Steve 4Nov12: Oh good grief, don't they have anything better to complain about? How many complaints were there that Phaser, Repeat, Reverse and Nyquist prompt were missing?
  • • Gale: None about the missing effects... Would be nice if these "mystery shoppers" would help editing the Manual, wouldn't it, but it shows us if we potentially have something wrong.
  • I find it no more difficult to read left to right. I normally read left to right and I think that the alternating colours draw the eye in a horizontal rather than vertical direction. I'm marginally +1 for left to right, but...
  • How do screen readers (other than JAWS) read the table? In rows or in columns?
  • Before I updated the list to add the missing effects, the table was one block of incomprehensible code. I presume that the complexity was the reason why it took so long for anyone to get round to updating it. The reformatted code is MUCH easier to maintain than the previous version AND it is easier to maintain in rows than columns.
    • Gale: Looks like you'll be outvoted, Steve. :=) The table wasn't complete because the effects weren't listed in the page. The-all-in-a-line Wiki formatting could be used for crosswise reading, too, so that's not relevant. Colouring can be changed to show downwards ordering, good point.

      I think most screen readers will read crosswise, but that doesn't outweigh the confusing mess the table presents to sighted users if ordered crosswise. This link suggests users on NVDA (which has no native shortcut to move down a table column) can use CTRL + ALT + down arrow . I cannot make it work, but either way I propose adding to Connie that list tables should read downwards. If this table is an issue for VI users (I'll ask David B. for his opinion) then we can think of some other custom TOC to resolve it.

    • Steve 4Nov12: If I'm outvoted then please go ahead and change it, but a couple of points to note:
      • We use left to right ordering elsewhere, for example: http://manual.audacityteam.org/m/index.php?title=Special:AllPages&from=AAC_Export_Options
        • Gale: That layout is forced on us by Wiki, and if you recall, Koz was complaining vehemently about the crosswise reading...
      • This accessibility guide recommends: "Make sure your text makes sense when read cell-by-cell, row-by-row, starting from the upper left. This is the default reading order of table cells for screen readers." http://accessibility.psu.edu/multicolumn
        • Gale: Yes. I have addressed that by adding a "summary" that says how the table is ordered. We are compliant in this data table but the accessibility guides don't really address list tables, which are the point at issue.
    • Ed 4Nov12 Maybe the fault is that it is a table. Most tables are set out conceptually to read like "a spreadsheet where the info is really a bunch of database forms". What we have here is an index being formatted in multiple columns--try this in MS Word or any other multi-column-able word processor and it will format top-to-bottom in the left column then flow into the right column and continue on. Maybe we should bite the bullet and do this "right" and get away from the table; is there any similar wiki form to replace the table with a linked multi-column?
      • Gale: Yes. And think also of rail station departure boards where they need two columns for the stations served by the train - I have not seen one yet where the stations read from left to right. That's what I meant by a custom TOC. I'm not sure what exactly the solution might be, but the current table (ordered downwards) works really well for most sighted people. I've put it back for the moment, and marked it as ToDo-2 to look at other options. If we keep the table, I'll change the colours to alternate downwards.
      • Steve: Could we use an unordered list and then style it with css? http://en.wikipedia.org/wiki/Help:List#Multi-column_bulleted_list
        • Peter 5Nov12: I'm still not convinced that we need the alphabetical list of effects on this page - and especially not in tabular form (some googling reveals that many folk think tables , especially for formatting, are "bad" and to be avoided). So here's a suggestion: if we do think that we need to retain an alphabetic list of effects why not create a new page for that, linked to from this page here. On that page each effect would be listed alphabetically one after t'other, vertically down the page, with the brief descriptive text that exists already on this page copied there. Thoughts? Possible link below to a draft page in my user-space (or the link could even be the H2 header itself?):
          Please see here for an alphabetical index of Effects, Generators and Analyzers.

• Steve: "Modern" thinking is that tables should be used for tabular data, lists for lists of things and CSS for layout and styling.

I think it is definitely useful to have effects grouped by function, but I do also like your alphabetical lists by menu. If I were to design this as a web page rather than wiki, I'd probably have a common page head for both "by function" and "by menu" with the appropriate content below as a server side include. I presume that we can't do that with the wiki software, but perhaps we could fake something similar?

Amplify	Compressor	GVerb	Paulstretch	Silence Finder
Auto Duck	Contrast	Hard Limiter	Phaser	Sliding Time Scale / Pitch Shift
BassBoost	Cross Fade In	High Pass Filter	Plot Spectrum	Sound Finder
Beat Finder	Cross Fade Out	Invert	Pluck	Tone
Change Pitch	Delay	Leveller	Regular Interval Labels	Tremolo
Change Speed	DTMF Tones	Low Pass Filter	Repair	Truncate Silence
Change Tempo	Echo	Noise	Repeat	Vocal Remover
Chirp	Equalization	Noise Removal	Reverse	Vocoder
Click Removal	Fade In	Normalize	Risset Drum	Wahwah
Click Track	Fade Out	Notch Filter	Sample Data Export
Clip Fix	Find Clipping	Nyquist Prompt	Silence

Gale: 03Sep12 ToDo-2 Moved TOC below our alphabetical index because people are missing our index. Maybe we want a custom TOC for effects groups also?

Effects by Function

Make the sound louder or quieter

• Amplify: This effect increases or decreases the volume of the audio you have selected.
• Auto Duck: Reduces (ducks) the volume of one or more tracks whenever the volume of a specified "control" track reaches a particular level. Typically used to make a music track softer whenever speech in a commentary track is heard.
• Compressor: Compresses the dynamic range by two alternative methods. The default "RMS" method makes the louder parts softer, but leaves the quieter audio alone. The alternative "peaks" method makes the entire audio louder, but amplifies the louder parts less than the quieter parts. Make-up gain can be applied to either method, making the result as loud as possible without clipping, but not changing the dynamic range further.
• Hard Limiter: An extreme compressor effect.
• Leveller: This effect makes quiet passages louder and loud passages quieter. It does this in a way that is different from the Compressor effect. As a result it does add some distortion to the processed audio. The only way to be sure if the effect does what you want is to try it. For example, applying this effect twice at its Heaviest setting on a normally-recorded voice can produce an "air traffic controller" effect.
• Normalize: Use the Normalize effect to set the maximum amplitude of a track, equalize the amplitudes of the left and right channels of a stereo track and optionally remove any DC offset from the track.

Fade a section in or fade it out

• Cross Fade In: Despite the name this effect does not do an automatic cross fade between two tracks or clips. Instead it applies a curve that is different from the one used by the Fade In effect. The curve used is one that will result in equal volume throughout the fade once the faded in and faded out regions are mixed.
• Cross Fade Out: Despite the name this effect does not do an automatic cross fade between two tracks or clips. Instead it applies a curve that is different from the one used by the Fade Out effect. The curve used is one that will result in equal volume throughout the fade once the faded in and faded out regions are mixed.
• Fade In: Applies a linear fade-in to the selected audio - the rapidity of the fade-in depends entirely on the length of the selection it is applied to. For a more customizable logarithmic fade, use the Envelope Tool on the Tools Toolbar.
• Fade Out: Applies a linear fade-out to the selected audio - the rapidity of the fade-out depends entirely on the length of the selection it is applied to. For a more customizable logarithmic fade, use the Envelope Tool on the Tools Toolbar.
  

Change the quality of the sound

• BassBoost: This is a smooth filter which can amplify the lower frequencies while leaving most of the other frequencies alone. It behaves just like the bass control on a stereo.
• Equalization: Adjusts the volume levels of particular frequencies.
• High Pass Filter: Passes frequencies above its cutoff frequency and attenuates frequencies below its cutoff frequency.
• Low Pass Filter: Passes frequencies below its cutoff frequency and attenuates frequencies above its cutoff frequency.
• Paulstretch: Use Paulstretch only for an extreme time-stretch or "stasis" effect, This may be useful for synthesizer pad sounds, identifying performance glitches or just creating interesting aural textures. Use Change Tempo or Sliding Time Scale rather than Paulstretch for tasks like slowing down a song to a "practice" tempo.
• Tremolo: Modulates the volume of the selection at the depth and rate selected in the dialog. The same as the tremolo effect familiar to guitar and keyboard players.
• Vocoder: Synthesizes audio (usually a voice) in the left channel of a stereo track with a carrier wave (typically white noise) in the right channel to produce a modified version of the left channel. Vocoding a normal voice with white noise will produce a robot-like voice for special effects.
• Wahwah: Rapid tone quality variations, like that guitar sound so popular in the 1970's.

Repair damaged audio

• Click Removal: Click Removal is designed to remove individual clicks on audio tracks and is especially suited to declicking recordings made from vinyl records, without damaging the rest of the audio.
• Clip Fix: Clip Fix attempts to reconstruct clipped regions by interpolating the lost signal.
• Noise Removal: This effect is ideal for removing constant background noise such as fans, tape noise, or hums. It will not work very well for removing talking or music in the background. More details here.
• Notch Filter: Greatly attenuate ("notch out") a narrow frequency band. This is a good way to remove mains hum or a whistle confined to a specific frequency with minimal damage to the remainder of the audio.
• Repair: Fix one particular short click, pop or other glitch no more than 128 samples long.

Make the sound faster, slower, lower pitched or higher pitched

• Change Pitch: Change the pitch of a track without changing its tempo.
• Change Speed: Change the speed of a track, also changing its pitch.
• Change Tempo: Change the tempo of a selection without changing its pitch.
• Sliding Time Scale / Pitch Shift: This effect allows you to make a continuous change to the tempo and/or pitch of a selection by choosing initial and/or final change values.
• Paulstretch: Use Paulstretch only for an extreme time-stretch or "stasis" effect, This may be useful for synthesizer pad sounds, identifying performance glitches or just creating interesting aural textures. Use Change Tempo or Sliding Time Scale rather than Paulstretch for tasks like slowing down a song to a "practice" tempo.
• Truncate Silence: Automatically try to find and eliminate audible silences. Don't use with faded audio.

Add reverberation or echo

• Delay: A configurable delay effect with variable delay time and pitch shifting of the delays.
• Echo: Repeats the selected audio again and again, normally softer each time. The delay time between each repeat is fixed, with no pause in between each repeat. For a more configurable echo effect with a variable delay time and pitch-changed echoes, see Delay
• GVerb: A reverb plug-in. Tips and example settings are available on our Wiki.

For details on the underlying principles of delay effects please see this page in the Wiki.

Remove vocals

• Invert: This effect flips the audio samples upside-down. This normally does not affect the sound of the audio at all. It is occasionally useful, for example when the left and right channels of a song both contain equal amounts of vocals, but unequal amounts of background instruments. By inverting one of the channels and not the other and then converting from stereo to mono, the vocals will cancel each other out, leaving just the instrumentals. This only works if the exact same vocal signal is present in both of the channels to begin with.
• Vocal Remover: Attempts to remove center-panned vocals from a stereo track. Help text is available from within the dialog.

Generate Tones

• Chirp: Generates four different types of tone waveform like the Tone Generator, but additionally allows setting of the starting and ending amplitude and frequency.
• DTMF Tones: Generates dual-tone multi-frequency (DTMF) tones like those produced by the keypad on telephones.
• Tone: Generates one of four different tone waveforms: Sine, Square, Sawtooth or Square (no alias), and a frequency between 1 Hz and half the current project rate.

Generate Silence or Noise

• Noise: Generates 'white', 'pink' or 'brown' noise.
• Silence: Creates audio of zero amplitude, the only configurable setting being duration.

Generate Instruments or Metronome

• Click Track: Generates a track with regularly spaced sounds at a specified tempo and number of beats per measure (bar).
• Pluck: A synthesized pluck tone with abrupt or gradual fade-out, and selectable pitch corresponding to a MIDI note.
• Risset Drum: Produces a realistic drum sound.

Analyze Amplitude or Other Audio Properties

• Contrast: Analyzes a single mono or stereo speech track to determine the average rms difference in volume (contrast) between foreground speech and background music, audience noise or similar. The purpose is to determine if the speech will be intelligible to the hard of hearing.
• Find Clipping: This displays runs of clipped samples in a Label Track, as a screen-reader accessible alternative to View > Show Clipping. A run must include at least one clipped sample, but may include unclipped samples too.
• Plot Spectrum: This takes the selected audio (which is a set of sound pressure values at points in time) and converts it to a graph of frequencies against amplitudes.
• Sample Data Export: This reads the values of successive samples from the selected audio and prints this data to a plain text, CSV or HTML file. Further information may be added as a "header" at the top of the file.

Divide Up Sounds or Silences using Labels

• Regular Interval Labels: Places labels in a long track so as to divide it into smaller, equally sized segments.
• Silence Finder: Divides a track up by placing point labels inside areas of silence.
• Sound Finder: Divides a track up by placing region labels for areas of sound that are separated by silence.

Mark Beats using Labels

• Beat Finder: Attempts to place labels at beats which are much louder than the surrounding audio. It's a fairly rough and ready tool, and won't necessarily work well on a typical modern pop music track with compressed dynamic range. If you don't get enough beats detected, try reducing the "Threshold Percentage" setting.