User:Stevethefiddle/Track Controls

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Proposal pages help us get from feature requests into actual plans. This proposal page is about rationalizing the behaviour of track buttons.
Proposal pages are used on an ongoing basis by the Audacity development team and are open to edits from visitors to the wiki. They are a good way to get community feedback on a proposal.

  • Note: Proposals for Google Summer of Code projects are significantly different in structure, are submitted via Google's web app and may or may not have a corresponding proposal page.

This is a first draft Please comment on the discussion page.

Proposed Feature

To rationalize the behaviour of the track buttons to provide a simple, consistent and flexible way to select which tracks are included in the export mix and which tracks can be heard when playing.


This topic has been the subject of several long and heated arguments. The purpose of this proposal is to take the heat out of the argument and come up with a solution that provides at least as much power and flexibility as the current Audacity 2.0.2 behaviour but in a more intuitive, consistent and easy to understand way. The approach taken in this proposal is to examine user cases to determine the required functionality and then to investigate possible ways to achieve that functionality.


The behaviour of Mute and Solo buttons changes depending on:

  • The behaviour set in preferences (3 options)
  • Whether using Export, Play or Mix and Render (3 options)

This is a lot of different behaviours. This proposal takes the position that it would be better if the behaviour of the buttons was consistent.

  • The manual states that: Mix and Render mixes all of the selected tracks down to a single mono or stereo track and simultaneously applies all real-time transformations for the track, such as gain, panning or resampling. In hardware terms this mix is equivalent to "Pre-mute, Post-fader" which for anyone familiar with hardware mixers is a weird and irrational combination.
  • The manual states that: (Mix and Render) "fixes" that mix by rendering the mix to a new track and deleting all the tracks that were selected. This is incorrect / misleading as it does not fix the mix but creates its own new mix regardless of the state of the Mute / Solo buttons.
  • If one track is soloed, other tracks are not normally heard, but another track will be heard when using Cut Preview unless the selected track is muted. Thus it appears that the mute button is honored, but the solo button is ignored. (bug 231)

Accessibility Issues

There is currently no way for visually impaired users to know if the mix they hear is the mix that will be exported without manually navigating through each track and examining the state of the Solo buttons.

Related Feature Requests:

  • Add mute/solo state to history
  • Add 'Honour solo state' checkboxes to the 'Export' and 'Export Multiple' dialogue boxes
  • Track Drop-Down menu > Solo and Mute choices

Related Proposals:

Redesigned Track Control Panel

Related Discussions:

User Cases

Working With Multi-Track Projects

When working with multi-track project it is very common that there will be some track that need to be excluded from the exported mix. This functionality is provided by the Mute button.

Properties of the Mute button:

  • One click to mute a track. The track will then be excluded from "the mix".
  • One click to unmute a track. The track will then be part of "the mix".

There is no need to consider different export/mix and render/playback mixes. "The Mix" is the same in each context. Mute means mute and the track is muted.

Monitoring one or more tracks It is often useful to be able to listen (monitor) one or more tracks independently from "the mix". The danger here is of confusion between what is heard and what is in "the mix". It is essential that it is totally clear that what is being monitored is not "the mix".

  • It must be possible to monitor one or more tracks regardless of their mute button status.
  • It must be clear that what is heard is not what will be exported, or exporting could be disabled while monitoring.

With large multi-track projects, the track buttons are likely to be hidden on the majority of tracks, so the visual state of the buttons cannot be relied on as an indication of whether tracks are being monitored or "the mix" is being heard.

  • Easy A/B comparison of alternative "takes" (very useful for live recordings, or when applying effects)

Additional Useful Behaviour

  • Option to mute or unmute all tracks (as now).
  • In large multi-track projects the track gain level may be very low so the ability to monitor "pre gain slider" would be useful. This could be achieved with a PFL button.

Transferring analogue recordings to digital

When transferring tapes / vinyl to digital format it is often necessary to apply corrective restoration for the removal of clicks, noise removal, corrective equalization etc. The ability to perform A/B (or A/B/C) comparisons is useful and should be available in a convenient manner.

Making Voice and Music Podcasts

When making a voice and music podcast the will be times when it is essential that all tracks can be heard together, but there may be times, such as when "dropping in" an additional live recorded voice, that it is useful to temporarily mute some tracks to avoid distraction. This is a simple case for muting tracks so that they are excluded from "the mix".

When mixing down a podcast, the user may want to experiment with different mixes and alternative "takes". Many of the issues relating to large multi-track projects will apply.

Making sub-mixes

With large projects or low powered machines it is often useful to mix down some of the tracks so as to reduce the track count. A user would not normally select a muted track as part of such a mix down. If one of the selected tracks was muted, then it would not be surprising if muting was honored, thus maintaining consistent behavior of "the Mix".

Mix-Down Prior to Export

There are several benefits to mixing down the entire project prior to export.

  • The project can be easily checked for over 0 dB clipping
  • The project can be normalized.
  • The start and end of the project may be trimmed
  • Fade-in / Fade-out can be easily added to the mix
  • Reverb, equalization, limiting, compression and other "mastering" effects can be applied to the mix.

The most convenient way to mix down the entire project is to select all (Ctrl+A) then Mix and Render. Mix and Render needs to honor the Mute button settings.

Other user cases

Please add any user cases that require special consideration.

Required Functionality

  1. The ability to mute tracks.
    1. So that tracks are not heard on playback.
    2. So that tracks are not exported.
      These are not necessarily separate options. It may be sufficient that Mute means that the track is excluded from both the export mix and from what is heard.
      On hardware mixing desks, the Mute function is usually before "Solo" and after "PFL", so that the Mute button will mute the signal to "Solo" but does not mute "PFL".
    3. It must be possible to un-mute individual tracks.
      • It is desirable to be able to mute or un-mute all tracks at once.
  2. The ability to listen to one or more tracks without losing the previously set (export) mix.
    This is currently achieved through the "Standard" Solo button behavior.
  3. The ability to make A/B (or A/B/C) track comparisons.
    This is currently achieved through the "Simple" Solo button behavior.
    1. One click to make one and only one track heard.
      • It is desirable that un-soloing all tracks will return the mix to the previous state.
      • "Un-solo All Tracks" would be a desirable feature.
  4. The ability to "Pre Fade Listen"
    This functionality is currently not available.
    1. PFL should be before Track Gain, Pan, Mute, envelopes and any additional real time effects in the signal chain.

If any combination of buttons cause "what is heard" to be different to "what is exported", (as will be the case for PFL) it must be clear to users that this is the case.


Pre Fade Level

Track Control Panel with PFL button pressed

When selected the PFL button would "light up" to give a visual indication that it is enabled and a sense of caution. Optionally there could be an additional "warning light" whenever any PFL buttons are depressed, for example in the Edit toolbar (or elsewhere). This would not help visually impaired users, but there should be no need to export during pre-fade listening. While any PFL button is pressed attempting to export will produce the error message "Cannot export while pre-fade listening. Release the PFL buttons on all tracks before exporting".

Mix and Render would also be disabled in a similar manner when PFL buttons are pressed.

PFL is pre Track Gain, pre Track Pan and pre real-time processing. The raw audio data as exists in the track is heard.

Selecting which buttons are available in the Track Control Panel

Proposed Track button options in preferences

If a button is disabled in preferences, it is also functionally disabled.

Supplementary Features:

  • Context menu accessed by right click on any of the Track buttons, or on the Track Information block (or left click with modifier key) provides options to enable / disable the track buttons (quicker and easier than going into preferences).
  • Move buttons above the Track Information (see Redesigned Track Control Panel)
  • Include information in the Mixing down to export Warning that Muted tracks are not included in the mix.
Export Warning
  • Track button states could be recorded in the History stack and so allow Undoing changes to return to the previous state.