Transparent Background in Rendering

Ok, so I’m making an Intro for my project but i want the intro to just be able to be put on top of a the video in the project if that makes sense. What I’m trying to say is I have a 20 second long audio piece but only 10 or so seconds of actual video. I want all that extra space that doesn’t have video, just sound, to be transparent so i can plop it over another video and it can play the audio but show the new video any idea how to do that? This is of course after I’ve edited and rendered that 20 second intro so then i can add it to multiple projects easily.

There may be a more elegant solution, but this is one way you could do it:

Create your intro as a separate MLT file, then “Open MLT XML as Clip” when adding it to other projects.

You may need to use a ChromaKey filter to have “just audio” for half of the clip, or something similar. If you try this and it doesn’t quite work, post a screenshot and I bet we can make it work.

I don’t see a way to accomplish this in one file (mp4), at least not with my limited editing skill. But this is what I would do…

Your 20sec audio track by itself. A1
Your 10sec video track by itself. V1 (Then add your video).
intro clip1


V1 & V2 are the same clip, Use the Hide (Eyeball) on V1, cut the video on V2, but just to the remaining clip on V2, apply a Mute filter. Save the mlt. Then new video will be added to V1. [Edit: Not V2, but V1 for new video]

intro clip2
If you were to “plop” a video on top if your intro it would turn into a transition. A 10 second transition, even with a transparent portion.

Then as @john_solo pointed out by saving just this to an MLT file then opening as MLT XML as Clip. If you’re using GPU experimental (setting), should have OpenGL (setting/display method) selected.

I would personally use Chromakey as john_solo suggested. Put your existing audio on an audio track, your existing video on V2 and a coloured panel on V1 the same length as your audio (Either import a colour or create/DL a plain coloured panel elsewhere and import the image). The default colour for chromakey is a bright green but you can use any colour which is as far away from the colours in your video as possible and use the eyedropper in the chromakey filter when you apply the effect.
Export the result which can then be imported as a single track and placed on V2 in your new video with the footage you want to show through the “transparent” section on V1. Apply the chromakey filter (the “simple” version is good for most applications like titles) to your title on V2 and the footage on V1 will show through as if the title were transparent as you want.
It IS possible to make a video with a transparent background using Hitfilm Express, but the resulting uncompressed AVI file required will be ENORMOUS compared to MP4.

If the other half of the video clip is used with this filter, wouldn’t it still make a transition once another clip is put 10 seconds on the end of it? What @SamCoffey is trying to do is an excellent idea and I want to do the same thing so I can learn, but I’ve got that mental block of dealing with the transition.

I’m not understanding the Chroma Key filter either and how it’s used to making a transparent background.

When the chroma key filter is applied shotcut will effectively treat a nominated colour as transparent so whatever is on the track below will show through.
If you want to experiment, try downloading this free clip

And put it on V2. Put anything you want on V1, preferably a still image. Apply the simple chroma key filter to V2 which is preset to the most commonly used shade of green - there is a slider on there too to adjust it’s sensitivity if you need it.
When you play it back or export what you’ve done, you will see the video of someone moving their phone over their hand but on the screen of the phone you will see the image or clip that you put on V1 as if the phone was seeing through the hand and the table.
When you create a clip to be chroma keyed later you don’t have to use green if it clashes with the rest of your clip - you can use any colour you want because you can use the dropper tool to pick any colour to be treated as transparent, but prerendered clips will usually be based on green or blue.
I hope that makes it clearer. If you want more hands on, step by step instructions there are a few decent tutorials on YouTube if you just search “shotcut chroma key”.

Here’s one to get you started


@Hudson555x, regarding your alternative solution, have you achieved transparency after opening an MLT XML as a clip? This doesn’t seem to be working for me, hence the chromakey.

@QDSOV, unfortunately using chromakey does have the limitation of not being able to Fade Out.

@SamCoffey The (now) obvious solution… as long as you don’t need any transparent overlays… is to NOT put an intro “on top of” the other videos in your project. Make a 20-second clip (possibly with the Open MLT XML as Clip trick), but put it UNDER, and Fade In (using opacity) your non-intro video clip 10 seconds in.

Chroma key doesn’t fade out?

I use fade out on chroma keyed clips all the time, or have I misunderstood what you’re saying?

@QDSOV Is there a way to apply a Fade Out Video filter so that it completes the fade at the 10 second mark of a 20 second clip? I know how to fade out a clip (with or without a chromakey filter) at the end of the clip, but that’s not the issue at hand.

Split the clip at the 10-second mark and apply the fade out to the first part of the clip.

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Edit - got ninjad by sauron :slight_smile:

If I understand you correctly (not sure I grasped it properly earlier) - 20 second clip but wanting a fade out at the 10 second mark to introduce new video whilst the remaining audio plays out?
If so then no I don’t know of a way of doing it with a single clip and tbh I wouldn’t. I’d just keep the audio and the shorter clip in a designated folder and import them as I needed them - only takes a few seconds to import 2 files and it gives you more options.
If I was restricted to working with a single 20 second file of combined video and audio, I’d split the clip at the 10 second mark and apply the fade to the first part then the second part could pick up the clip below via chroma key which could be faded in if required.
Another way of getting around it I’d consider using myself, would be to end the 10 second video clip with an animated transition which reveals the chroma key for the second half rather than a fade out and would avoid the need to split the clip.
Either way - separate clips or single chroma key based clip - takes very little time. I guess it’s down to the method you prefer and the options you want available to you.

btw - are you the same guy as Jon Solo who does Star Wars and Disney related videos on YouTube, or is the nominative similarity a coincidence?

I am not that guy, and have no other internet presence with this name.

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It was not about saving the alternative as MLT XML as a clip, I was merely warning having the right settings if you were to use MTL XML as a clip, as I didn’t at one time and I had a bunch of problems.

Although I have not tried the ChromaKey filter, I finally understand it, and it’s actually a very clever idea. :cowboy_hat_face:

And now that I understand the ChormaKey filter, if it was just one file, how would you control the transition aspect? If I understand the OP correctly wants one file to be a very static intro clip, which any additional video would be set on top of this intro, at 10 seconds to have the audio. Is it possible to put one clip on top of another clip without a transition?

I just came up with a 2nd alternative. No filters, one file as OP wants. Just has to drag the new/unique video to the 10 second mark in the intro, still creating the transition. OP would have to make the transition adjustment every time a new subject video was in brought over the intro clip.
Then to the Properties tab: Transition / Cut / Position 0% / Audio Mix A 0%
transition cut

I was assuming that multiple tracks would be used, which does not require a transition, as long as the “upper” track has transparency and is composited on top of the other. I don’t claim to know exactly what the OP was asking for, though. If we’re limited to one video track, I like your transition solution!

Perhaps the OP will give us more information… :thinking: