Should I remove unused Fade In/Out Audio?

While reading another discussion, it reminded me of something I was wondering about a while ago. But I was too shy to ask about it then, considering it to fall under the dumb questions category.

It’s about the fact that, when adding a Fade out to a clip, both Fade Out Video and Fade Out Audio are created. Even if there is no audio on that clip.

My question is : Is it best to remove Fade Out Audio when it’s not needed ? If there are, say, a hundred unused audio fade ins and fade outs in a project, will it not slow down Shotcut, even a little bit ?

Intersting question but irrelevant for the output :slight_smile:
I would guess when there is no audio involved the fade out audio filter has nothing to do and it wouldn’t waste any time. It probably just is there as default - but this could be improved - just guessing :slight_smile:

By “for the output” do you mean : after exporting the video ?
I’m only concerned about when editing and exporting a project. Even if Shotcut does not use the filter, the data is still there.

To give you an analogy, suppose you go on a hiking trip. If you bring 3 litres of water but only use 1, you still carry 2 kilos of unnecessary weight that will make you use more energy than you should have.

2 Likes

Maybe if you took beer to the excursion, you wouldn’t come back with 2 liters. :grin:

3 Likes

True ! :smile: But I wouldn’t walk very far either :sweat:

1 Like

Yes, i meant after exort - the final mp4 (or whatever format) won’t notice.

Not 100% sure what you mean with the second part. Again, there is no extra load for the final output (exported file will not be bigger or more difficult to decode). There is (my guessing) also no extra load to the editor (Shotcut) and to the encoding process - because there is no extra work to do :slight_smile:

If you set the clip to have no audio in Properties, the audio fades will not automatically be applied.
shotcut_2020-09-10_11-47-21

1 Like

@Hudson555x, thanks for the tip.
But it only works for clips who already have an audio track.
Shotcut will still automatically apply both audio and video fades to all the other clips.

While watching a movie tonight (guess what movie ?) I performed this very scientific test:

First, I created 2 Shotcut projects:

  • with_fadeaudio.mlt
  • without_fadeaudio.mlt

Each project have 16 tracks.
Each track have 16 identical image clips. So a total of 256 clips.
Each clip is 3 seconds long with a 1 second fade-in and a 1 second fade-out.
Each track have a 1 second delay from the previous one (except track 1).

Difference between the two projects? You guessed it : In without_fadeaudio.mlt I removed all Fade In Audio and all Fade Out Audio. I remind you that those were created automatically, but are not used since there is no audio in the clips.

Then I exported each project 3 times to see if removing the unused audio fades would make a difference.

First let’s look at the MLT (melt… melt… melt) files and the exported videos :

without_fadeaudio.mlt is about 200k smaller. Makes sense. 2 liters of unused water.
Both exported videos are identical. This also makes sense.

Now, let’s look at how long it took to export each project.

Export list of the project with the audio fade-ins and fade-outs :

Export list of the project where I removed the audio fade-ins and fade-out.

So, according to these results (and if the way I did the test is worth anything), it does make a difference when the unused audio fades are removed. But obviously, it’s not worth the time it takes to remove them just to save about 3 minutes of export time.

Good night

5 Likes

Interesting results - didn’t think it would come out like this. At least the exported mp4 are the same size :slight_smile: There i space for improvements in SC :slight_smile:

1 Like

I would never have thought of it. Good job. :+1:
By the way, I really liked that movie. :star_struck:

1 Like

A very useful test, @MusicalBox, and it’s good to know this information. Thanks! :+1:

1 Like

I’d like to mention that my intention was not to expose a flaw or a bug. I understand the reason why audio fade is added at the same time as video fade. A different slider for audio fade would probably cause more confusion than anything else. I was just curious to know if it was preferable to remove the unused fades. Maybe a bit of OCD was involved in there too.

I have bookmarked this to optimize it. Hudson pointed out that audio fades are not added on video-only clips, and it is a fairly simple matter to extend this behavior to images and video-only generators.

6 Likes