Mix and Render Track Levels, Serious BUG

First off, Thank you for making available Audacity to the audio community in General.

I’ve come across a serious bug for downmix (mix and render to new track) with respect to the output Levels.

There is a requirement to Select Tracks (Ctrl A) in order to use the Mix and Render to New Track Function.

Assuming multiple tracks with a few tracks muted (say 7 Tracks with 2 Tracks Muted).

  1. Selecting all tracks via Ctrl A (including the muted tracks) affects the output levels in the mix tracks and causes it to be very high.
  2. Selecting only unmuted tracks (by reordering the tracks and selecting the first track contents, Home Shift-End Shift-DwnArrow), gives correct output levels for the Mix Track.

It appears that audacity is not excluding the mix levels of muted tracks while creating the downmix. For each selected Muted Track, the output level gets louder and louder.

If not change the algorithm, could you at least provide an option under the Select menu (Select All non-muted tracks) so that the output levels are computed correctly and the result usable.

Audacity version 2.2.2 (portable edition) on Windows 10.

Thanks in Advance

Yes, as is described in the manual: Mixing Audio Tracks - Audacity Manual
All selected tracks are mixed, regardless if the Mute or Solo buttons…

I agree that the inconsistency between “mixing” and “exporting” is a bit confusing, but it is not a “bug” because it is doing what it has been designed to do.
I guess the developer’s reasoning was “Why would you select a track for mixing if you don’t want to mix it?”

Correct me if I’m wrong:

Export to Wav does not mix muted tracks (the levels don’t seem to be affected)
Mix and Render to New Track mixes all tracks regardless of mute or solo

3 Followup questions, requests

  1. Is it possible to have arm for mix, or exclude from mix toggle for each track?
    I see there are no ‘arm buttons’ like other daws except for mute and solo.

  2. Is it possible to have checkboxes on the Export to Wav window: “After export, open track” , “After Export, Import Track”
    This was the function I was expecting from “Mix and Render to New Track” to avoid having to manually open the file after waiting for export, then having to wait again to read and build the waveform.

  3. Is there a feature whereby Audacity can save the waveform instead of having to read it each time, is helpful in non-ssd scenarios.

I apologize for not reading the manual in detail, I would suggest a rename from ‘Mix and Render’ to “Mix and Render All”, but that’s just me.

My current workflow is Mixing down 5.1 Source tracks to Stereo and checking for clipping and quality of Downmix.

There are some areas for improvement, and I sure hope my suggestions/requests do not sound ostentatious.
In some respects, Audacity is much better than well known DAWs, in others it begs to be different.

Thank you Steve, for your prompt response.

Correct on both counts. That’s the “inconsistency” that I was referring to.

In Audacity, it is called “selecting”, and the same method of “arming” (selecting) applies to most other operations.

There are three kinds of “selection”:

  1. Track selection: The info box on the left end of the track is highlighted when a track is selected.
  2. Time selection: The selected time period is highlighted in the Time Line above the track window.

Note that when selecting audio, for example to apply an effect, the selection is both a “track selection” and a “time selection” and the selected audio is hughlighted.
Mixing is currently limited to whole tracks. so only the track selection is important.

A track’s “selectedness” can be toggled by:

  • Up / down cursor keys to move “focus” from one track to another (the track that has focus is indicated by a yellow border)
  • “Return” key to toggle track selection on/off
  1. Frequency selection (tracks in Spectrogram view, for “spectral effects” only)

Mix and Render is useful for mixing down before export.
Mixing multiple tracks will usually affect the overall amplitude level, so mixing down provides an effective way to check that the peak level does not go into clipping.

Unless you are exporting in a low quality audio format, the exported file should sound identical to the mixed down track.

When I’m working with multi-track projects, this is what I do:

  1. Do all the editing / processing with multiple tracks and adjust so that it sounds as I want it to.

  2. Select all tracks that I want in the mix, then “Mix and Render to New Track”.

  3. “Solo” the mix-down track

  4. Normalize the mix-down track

  5. Export the (soloed) mix-down track.

  6. If I need to save the project, un-solo the mix-down track and mute it, then save the project. The un-mixed tracks are still available should I need to work on them further.

A saved project may open more quickly than importing an audio file.
(see also: Managing Audacity Projects - Audacity Manual)

Probably the biggest difference is that Audacity isn’t really a “DAW”, it’s an “audio editor”. Where as "DAW"s are usually “real-time processing”, audio editors act directly and immediately on the selected audio. When you process audio in Audacity, you see the waveform change because the audio data has changed. In real-time DAW application, the waveform does not visibly change when processed, because the processing is not actually being applied - it is just being played with the effects, and the effects are not applied until you mix down or export.

In a sense, Audacity provides WYSIWYG editing, whereas “real-time DAW” applications provide “non-destructive” editing (the audio data is not actually changed until mix down / export). There are pros and cons to both approaches, and for complex jobs both may be used side by side.

Thank you Steve.

I just got round to figuring out how to select non-contiguous tracks.

Hold down Ctrl and select the tracks by clicking anywhere on each track. Then Home and Shift End, retains track cursors and extends selection from in to out.
I still would vote for a ‘Select All Unmuted Tracks’ feature, as the number of tracks visible with normal track height on a MAC 27 inch, is about 9.

Yes a WYSIWYG audio editor better describes it. It processes mixes significantly faster (nearly 3X) than Adobe Audition, and that is no mean feat.

Thanks again!

This can help:
“View menu > Track Size > Collapse All Tracks / Expand All Tracks”

Looking through the ‘Track Selection Feature’ again,

This implies I can skip the second step here:

Hold down Ctrl and select the tracks by clicking anywhere on each track.
SKIP: Then Home and Shift End, retains track cursors and extends selection from in to out.

I need not be concerned about Selecting the Time, because Mix and Render only takes the Track Selection Info?
I can ignore the auto selected time segment, this is unavoidable as clicking on various tracks is almost never on the same timecode and this results in a short segment selection.

Is there another way to select Tracks? Without selecting Time for example?

Mix and Render always takes the entire track, so it doesn’t matter how much of the track is selected (even none at all is OK), provided that the “track” is selected (as indicated by the track Info / control panel being highlighted).

“Selection” is such an important feature in Audacity, there are lots of ways to do it.
I mostly use the Mouse, Mouse wheel, Shift + Mouse. Ctrl + Mouse, for selecting, scrolling and zooming.
See here for more info: Selecting Audio - Audacity Manual