On-demand Loading again


=> I take part of a project that uses Audacity to analyse night recordings, in order to have a better knowledge of birds migration.
So, we ask Audacity to show spectrogramma, to select parts and to make labels.

=> But our recordings, in WAV, are long because we record 8 or 9 hours : so, when we ask Audacity to open these kind of file, it takes a loooooooooooot of time…(yes, it could be long…and that increases coffee consumption…)

=> Before Audacity 2.3.3, it was possible to import non-compressed files with On-Demand Loading : the file was open immediatley.

=> This option has been deleted because it could cause problems at the project if the non-compressed file is delete/rename/move.https://manual.audacityteam.org/man/on_demand_loading.html

=> But in our case, we don’t need to create a project : so, is this possible to have access to this option again ? With 2.3.3 and followings ?

Thank you for help.


It’s not my decision (don’t shoot the messenger :wink:), but on demand loading is unlikely to be coming back. With modern hardware (particularly with a SSD) the benefits are negligible but there are considerable technical problems trying to maintain that code, as well as potential bear traps for unwary users.

Personally I hate it when software / hardware manufacturers want to persuade me to upgrade my hardware, especially for a task that I was doing perfectly well on old hardware, but having said that, I would highly recommend getting a SSD - they make a world of difference to computer performance (including MUCH faster boot time), especially when working with large amounts of data.

Hi Hervé

I did some timed testing on W10 on my HP Envy PC that has both a 256GB SSD and an onboard 1TB hard disk.

I created a 9 hour 24-bit mono WAV file (that’s just under the maximum 4GB limit for WAV files) as my test input for Import.

Surprisingly the difference between Importing the file from SSD was only marginally faster than from the spinning-metal hard disk.

1) With the current release 2.4.2
Import from SSD took 53 seconds
Import from HD took 55 seconds
So only a minimal difference between the two

2) I then tried the RC06 Release Candidate - for the upcoming 3.0.0 with the changed project file structure (unified into a single file)
Import from SSD took 1 min 29 secs
Import from HD took 1 min 03 secs

This I find totally puzzling as to why the SSD import should take longer than from HD :confused:
But although it takes a little longer with the new database structure with the HD (only 14%)

3) I then tried 2.3.2 with ODL
Import from SSD took less than 1 second - plus 25 seconds to draw the waveform
Import from HD took less than 1 second - plus 35 seconds to draw the waveform

So my advice to you, if speed of import is you major criterion, then stick with ODL in Audacity 2.3.2.
Or you may just need to get a faster PC - on mine I don’t regard a minute so so to import a 4GB maximum size WAV file as too imposing.

But I would echo Steve’s comment: it is very unlikely that ODL would be re-introduced into current Audacity as the reason it was removed was that far too many people were damaging and losing their valuable projects.



=> Thank you very much for your answers/tests Steve and waxcylinder !

=> I understand why ODL has been removed…and I don’t want to see someone in a bear trap… :confused:

=> What’s frustrating is that ODL can’t be “dangerous” for us, because we don’t create a project .aud…

=>In my case, i can’t install the ils version where ODL is available (a dll pb)…and on my oooold PC (Windows 7, but it works very well for everything else i need), Audacity opens a 3go file in 8min.

=> Of course, an answer is to buy better computer and/or SSD, but it’s not possible for everyone, and I won’t do that “just” for 1 task.

=> So, is this possible/difficult to create a 2.3.3 (for ex), with ODL (with Addon?..)…hum…just for us ? I guess it would be surprising…but i try…

Two options occur to me - perhaps one would be suitable:

  1. Continue using Audacity 2.3.2

  2. Split the huge WAV files into more manageable size files (say 30 minutes or an hour) before importing into Audacity.
    This can be done extremely quickly using a command line app such as SoX (http://sox.sourceforge.net/)
    Example, to split “huge.wav” into 30 minute files “small001.wav”, “small002.wav”, …

sox huge.wav small.wav trim 0 1800 : newfile : restart

The option 1 isn’t usable for me : my PC doesn’t want to run Audacity 2.3.2 : dll pb

I’ll try the option 2 : thank you !