Using "select-all" just for audio

I need to run some effects on multiple tracks.
It seems easier to just use “select-all” and then run the effects once.
Unfortunately “select-all” is highlighting an area that covers the length of the longest track.
This creates a dead area at the end of the shorter tracks and also increases the overall length of the shorter tracks to match the longest one.

Is there a simple way to use “select-all” and highlight just the audio in each track?

I took a look at the audio track page:

Holding SHIFT while clicking selects all this track’s audio, keeping already selected tracks selected.
(keyboard: use UP or DOWN to give the track focus, then ENTER to select it; hold SHIFT then use UP or DOWN to extend selection into another track. Read keyboard selection for more).

That would still require selecting each track one at a time.

Is there another short cut that I can use?

You can use HOME then SHIFT + K to select all of a track without the selection extending to the end point of longer tracks.

Audacity doesn’t support selections that are at different points in the Timeline for different track, but this should not be a problem unless you are trying to use generator effects (which will generate into white space).


You’re right, it is rather queer. I don’t know why Audacity passes short sounds to the effect, as if they would have the same duration as the longest one.
I guess that it simplifies the code execution.
I can only talk for Nyquist effects. If I want to write a really multi-track selection suitable plug-in, I have to trim the sound, i.e. remove all zeros (didital silence) before the sound is returned to audacity.
Since this procedure is time-consuming, it is almost never applied in a plug-in. In fact, I am only aware of my align-track plug-in, that does this (in order to align tracks end-to-end without unwanted pauses).
Aligning tracks end-to-end
However, it does this also for the beginning of the track, which is not desired for tracks that were deliberately shifted.

Fortunately, There is a command that removes the unwanted silence from your audio (after processing):

Edit > Clip Boundaries > Detach at Silence (ctrl-alt-j)

Thus, just select all as usual, apply the effect you want and execute the command above.

Thanks for the quick responses.

Detach at Silence was a great, simple solution.

I thought everything was working but I had problems with some live albums.
I ended up without about 5 seconds of silence appended to the tracks.

I see, I did not realise that JHL was using Nyquist effects, which join separate clips together by converting white space to silence: .

Yes, though you have to use 32-bit projects for this to work, otherwise Dither noise is added (Detach at Silences works on absolute silence). The dither is added because all internal processing is done in 32-bit float, but if the track is 16-bit or 24-bit integer, that integer format is returned to the track.

Or, set “Dither” to “None” under “High-quality conversion” in the Quality Preferences.

Please check if the problem is as above. Also if you are importing files like WMA or M4A that require FFmpeg, these only import in 16-bit resolution even if your quality setting is 32-bit. In this case, you will have to turn dither off.

Alternatively use built-in effects (above the divider in the Effect Menu) which don’t join clips together by silence (or VST alternatives).

Alternatively if you are working with imported files, create a batch processing Chain for your effects then apply that Chain to files, which only works one track at a time.


Of these options it is much better to set the tracks to 32 bit float.
Turning off dither will prevent dither noise from being added, but at the expenses of harmonic distortion being created. Dither is used to prevent the harmonic distortion that is created by quantize error. Setting the track to 32 bit float avoids quantize errors because the processed audio does not need to be converted to a lower quality format and thus dither is not required and not applied.

I would recommend not turning dither off in this case. Much better to change the track to 32 bit float format before processing.
To do this, click on the track name and then from the drop down menu select “Set Sample Format > 32-bit float”.

Yes 32-bit is generally preferred as Default Sample Format in the Quality settings because dither will then not be required until export (assuming export to a 16-bit file is required, as is common).

A few people prefer to turn dither off (at least for export) because it can be audible in headphones in previously silent audio. However it’s more likely to be audible if you had a 16-bit project, so applied dither noise several times, or amplified it in running an effect.

Thanks, I missed that possibility.

I wonder if Audacity should not perform that conversion itself when the Quality settings are more than 16-bit? LRN felt there was no obvious or safe way of having FFmpeg do it.


If it is possible to do so (and I would expect that to be possible), then I’d agree that Audacity should.