data folders larger when stereo tracks to mono why?

[frew_frew]

Hello,

When I save a project with 8 stereo tracks at around 9 min long the date folder is 200MB.

When do Tracks> Stereo track to mono for all the tracks and save the project, the data folder is 731MB.

I thought the mono tracks would actually produce a smaller data folder, but instead much larger.

Just curious why that is.

Thanks for any ideas.

frew

[steve]

You've not given enough detail.
Have you taken into account dependencies (http://manual.audacityteam.org/man/auda ... pendencies) and UNDO history?
Do the tracks have the same sample rate and sample format?

The UNDO history is cleared when the project is closed or removed via the "View > History" window (http://manual.audacityteam.org/man/view ... ml#history).

[Gale Andrews]

More detailed answer, given I had already written it before seeing Steve's reply.

When I save a project with 8 stereo tracks at around 9 min long the date folder is 200MB.

By default that should take about 1.4 GB of space, unless your project rate bottom left of Audacity is way below the recommended 44100 Hz.

I would guess these tracks are imported WAV or AIFF files and you have chosen not to copy them into the project. This saves space but only until you edit the audio. See Import / Export Preferences.

When do Tracks> Stereo track to mono for all the tracks and save the project, the data folder is 731MB.

I thought the mono tracks would actually produce a smaller data folder, but instead much larger.

Just curious why that is.

I think Stereo Track to Mono would copy in the data if you had not already done so, which would make the project larger.

Also remember that Audacity has Undo and Redo ability which needs disk space. Every new action adds to disk space usage until you close the project or use View > History... to remove Undo steps.

When you close the project all Undo/Redo steps are removed and the data used is solely that for the visible project as you saved it.


Gale

[frew_frew]

Hi,

-no dependencies (pretty sure about that)
...ie I think all the date the project needs is in the data folder.
I always like to have all the wav data in the project data folder, so I always
use the "safest" way when opening a project, the "make a copy" way
...also the "when saving project that depends on other audio files" I have
"ask user" and it never asks, indicating no dependencies I think.

-project closed, so no undo history

Do the tracks have the same sample rate and sample format?"

yes, all 16 bit, 44100Hz

-project rate 44100hz

By default that should take about 1.4 GB of space

-perhaps generally smaller project data folder overall in my case because parts of some tracks are empty,
ie I recorded parts of some tracks for only a few bars at perhaps 5 minutes into the piece

I think Stereo Track to Mono would copy in the data if you had not already done so, which would make the project larger

quite sure I had already done so as noted above I think, if I'm understanding this correctly

So lets say one has a project with 8 stereo tracks with no dependencies, and then closes the project.
Are we saying that if nothing else is changed at all except all tracks have been made stereo to mono,
then close the project, that the mono tracks project data folder should be around half the size?
I thought they might be around half the data size.

Thanks for any more ideas.

frew

[steve]

-perhaps generally smaller project data folder overall in my case because parts of some tracks are empty,

Empty space in a track has no data (size zero).
When empty space is rendered as silence, samples with zero amplitude are generated in place of the empty space.
"Silence" (zero amplitude samples) has the same amount of data as any other audio (by default, 44100 samples per second per channel with 4 bytes per sample).

(There is a special case when generating silence, in that Audacity will use a kind of place-holder rather than sample data to represent silence - in this special case the silence is zero bytes.)

"Do the tracks have the same sample rate and sample format?"

yes, all 16 bit, 44100Hz

So you have changed Audacity's default settings to lower quality? Why did you do that?

[Gale Andrews]

So lets say one has a project with 8 stereo tracks with no dependencies, and then closes the project.
Are we saying that if nothing else is changed at all except all tracks have been made stereo to mono,
then close the project, that the mono tracks project data folder should be around half the size?

Yes I believe so, assuming the audio in each track is different.


Gale

[frew_frew]

edit: all along I've had Preferences> Quality> Default sample (edit: format) 16 bit, because I thought it would
be easier on my older system, and that it would sound well enough, less dropouts in recording with lower latencies
during recording, and that it might take less room on hard drive in data folders...

Empty space in a track has no data (size zero).
When empty space is rendered as silence, samples with zero amplitude are generated in place of the empty space.
"Silence" (zero amplitude samples) has the same amount of data as any other audio (by default, 44100 samples per second per channel with 4 bytes per sample).

..sorry, not following exactly...no rendering taking place yet, just saving the project

assuming the audio in each track is different

sorry, not sure what that's referring to


So I have a situation where I like to sometimes make all my tracks stereo to mono,
even though I initially record them stereo.
I took a few projects that had stereo tracks, opened them, and only did a stereo to mono for each track,
then saved the projects with new names, closed the projects, and checked their data folder sizes.
I was surprised to see the data folders of the mono track folders were over three times as big
as the original stereo track projects.

Oh well, not a major problem...just wondering why the data folders got bigger rather than smaller after
only making the tracks stereo to mono.

Thanks,

frew

[steve]

..sorry, not following exactly...no rendering taking place yet, just saving the project

I thought you were doing: "Tracks menu > Stereo Track to Mono".
If so, then that "mixes" the two channels of the stereo track to render a new mono track. Any empty space between audio clips will be rendered as silence.

Example:
Stereo track:

firsttrack001.png (9.98 KiB) Viewed 412 times

After converting (mixing) to mono:

firsttrack002.png (5.39 KiB) Viewed 412 times

[frew_frew]

I thought you were doing: "Tracks menu > Stereo Track to Mono".
If so, then that "mixes" the two channels of the stereo track to render a new mono track. Any empty space between audio clips will be rendered as silence.

Ah yes, I see now.
Many of my stereo tracks had lots of empty spaces before and after audio clips.
So apparently when a project is saved in what I'm calling it's original stereo track state,
with all the empty spaces before and after audio clips, Audacity is not using hard drive
space to store those spaces.
When the stereo tracks are changed to mono, something happens where Audacity now has to
deal with those spaces by giving them actual .au files, thus accounting for the larger data folder
sizes in situations where stereo tracks with spaces in them have been actually "rendered" to mono.
(or something like that)

Just a fine point, but it may be nice to have a little info about this in the help file, or perhaps
Tracks> Render Stereo Track to mono (with perhaps info that pops up mentioning it will increase
project size if Stereo Tracks contain empty spaces before and and/or after audio clips).

You've really helped a lot and I really appreciate it.

Thanks again,

frew

[frew_frew]

Well, I just deleted all the stereo tracks that had spaces, and was left with three stereo tracks, with no spaces,
around 7min long each track, and the data folder is 47MB.

After all three tracks stereo to mono, data folder 208 MB.

So I have another theory, perhaps so simple we overlooked it because I did not give thorough information.

Each of my three stereo tracks consists of not one continuous recording, but rather 30 second recordings
copied and pasted numerous times to make up a 7 min tracks. So audacity is probably just reusing those
clips, not having separate data for each clip...as long as the tracks remain stereo, as originally recorded.

But when rendered to mono by Track> Stereo track to mono, the whole track now has to be turned into
those au files, thus accounting for the very much larger data folder size.

This is probably what accounts for the majority of the data file size increase, along with what you've presented
in your images of any empty space between audio clips will be rendered as silence.

Sorry I did not mention from the beginning that my stereo tracks had multiple repetitions of audio clips.

Does this sound like what may be happening to partially account for the larger data folder sizes when I
turn all my stereo tracks into mono tracks?

Thanks,

frew