Macros

Peter 12Feb13: This page is now published, though not visible (except via a link on my user pages and through Search). Please, therefore, do not edit either of the two Strawmen #2 & User:PeterSampson/Chains - for batch processing and effects automation - Strawman-3|#3]] for detailed content as they are for illustrative purposes only.

• Peter 12Feb13:I really do prefer the top version on the Talk page where the "Examples" note div is positioned at the foot of the page.

A Chain is a sequence of preconfigured commands in a set order (mainly effects) that can be applied automatically to projects or audio files. Any built-in or Nyquist effect shown in the Effect Menu and export commands can be added to a Chain. The two uses of Chains are for:

• Batch processing (where many audio files are processed unattended with one or more effects then saved to a new file),
• Effects automation (where the track or tracks in the current project are subjected to the same prescribed sequence of effects that are used for other projects, and optionally, a file exported).

See the examples below.

Peter 12Feb13: I don't like the title "Workflow" for this section. How about "Using Chains" or similar?

Workflow

Gale 11Feb13: Ed wants "If you need to edit an existing Chain or create a new one use File > Edit Chains". I like to keep the spans at the start but "First (if required) use File > Edit Chains... ..." would be OK. Ed thinks this is acceptable but not optimal. Maybe I'm coming round to Ed's view slightly.

• Peter 12Feb13: I accordingly tweaked the wording for step-1

There are two related Chain commands in the File Menu called Edit Chains and Apply Chain. The workflow is as follows.

1. First, use File > Edit Chains... if you need to create a new Chain or to edit an existing Chain.
   To save an audio file as part of the Chain process, you must add an Export command.
2. Second, use File > Apply Chain... to select one of the existing chains and apply it to either:
   • the project in the current window (this is essentially a method of effects automation) or
   • a selected list of external audio files (this is essentially an unattended batch processing of many individual items).

Peter 12Feb13: I have simplified the first step. The dear reader was being given far too much overcomplicated and confusing detail at too early a stage on this page - even I don't really understand the second bullet point about "MP3_56k". That level of detail really belongs on the Edit Chains page imo.

1. First, use File > Edit Chains... to create a new Chain or to edit an existing Chain (if required).
   • To save an audio file as part of the Chain process, you must either:
     • add an Export command for 16-bit WAV, MP3, FLAC or OGG (which use any currently set "Options" for that format in the File Export Dialog ) or
     • use one or both commands to save "MP3_56k" (a low quality MP3 at 56 kbps bit rate).

Examples:

• A "batch processing" Chain might use Compressor to reduce the dynamic range of multiple WAV files (also normalizing them to maximum amplitude of 0 dB), then convert them to MP3 format.
• An "effects automation" Chain for the current project might run:
  1. Normalize with settings of:
     • Remove any DC offset
     • -10 dB (to allow for boosting frequencies later in the Chain without clipping)
  2. Noise Removal
  3. Equalization (to perform the frequency adjustment)
  4. Normalize again at different settings (without offset removal, setting a final amplitude of -1 dB).

Edit Chains

Enables you to either edit, remove or rename existing Chains, or add a new Chain. The Chain can include a number of common Audacity functions and effects to be executed in any order you specify. In many cases, the parameters for each command in the Chain can be specified within the Edit Chains window.

Accessed by: File > Edit Chains...

The left hand box in the dialog box (labeled Chains) Chains contains a list of already defined chains. You can define the name of a new chain and select which chain is active by using the Add, Remove and Rename buttons.

The right hand box (labeled Chain) lists the ordered sequence of commands for the chain selected in the "Chains" box on the left. Here you can add or remove commands for the selected chain, change the order in which the commands execute in the chain, or edit the parameters for some effects in the chain.

For further details see the Edit Chains page.

Apply Chain

Enables you to select a Chain and apply it to either the entirety of the current project, to a single audio file or to a group of specifically selected audio files in a single directory.

Accessed by: File > Apply Chain...

The dialog window contains the list of all your current chains. Use left-click (or use the Up or Down arrow on the keyboard) to select the Chain you want to apply.

Then use the Apply to Current Project button for effects automation or the Apply to Files button to apply the selected chain to a set of files which you select (you must have a new, empty Audacity Project window open to use this option).

For more details see the Apply Chain page.