Hi,
I want to do a little animaion with a transparent background, but I'm not able to rendre the vidéo with a tranparent even if I try with PNG. Is this normal? If so, is it planned to add this function in a future version?

Thanks

I think that you have to use Alpha manipulation -> Chroma key or Color selection to make the background color transparent.

It’s not possible as Kdenlive renders always with a back background. I’m not sure if this can be changed. I think in Shotcut this is possible.

Well, rendering with transparent background is possible, but quite a bit tricky and not sure if of more than academic interest.
There is codec qtrle which allows rendering with alpha-channel. So what you need is a new rendering profile to use the qtlre encoder and a pix_fmt of rgba to add alpha channel
Create a render profile, give it a name and set file extension to "mov" and enter

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vcodec=qtrle pix_fmt=argb

in the parameter field. Rendering with this profile would be it, if kdenlive does sometimes add a hidden black track. To make use of the alpha channel, you need, instead of rendering to a file, create a script in the rendering dialog. I created a script called "transparent.sh" and kdenlive creates two files: transparent.sh and transparent.sh.mlt. Open the .mlt-file with a text editor and look for lines like:

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 <tractor title="Anonymous Submission" id="maintractor" global_feed="1" in="0" out="1970">
  <track producer="black_track"/>


If don't see the line

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<track producer="black_track"/>

kdenlive did not add the hidden black track, IF you see the line, remove it and run transparent.sh. you will get a video with transparent background.

Thank you for this explanation.

This is more than of academic interest. People ask for videos with transparent background which can be re-imported into the timeline. Like for animation, logos, after rotoscopeing, etc .

If you like, would you share your script? I would post an instruction in the manual how to render videos with transparent background.

Hi Merlimau,
yes, I created an example archive, about 20MB ... any idea where to upload?
Joe

I checked but unfortunately there is no way to upload such a big file. Could you share via Dropbox or similar?

Oh yes, dropbox ... forgot about this at all.
I put some files in a dropbox directory:

• videos/kdenlive-logo.mov: A simple transparent animated kdelive logo as transparent example
• kdenlive-logo.kdenlive: A project which uses the above logo to create a new transparent video
• transparent.sh: A sample script generated by kdenlive's render dialog
• transparent.sh.mlt: A samplemlt project generated by kdenlive's render dialog

Do not forget to create a render profile with vcodec=qtrle and pix_fmt=argb (As described in a previous post).

Let me know if the link works...
/jr

I could download your samples from the dropbox. And yes, it works according your steps!
I'll create a description in the manual how to do that and upload the render profiles in a manner that you can download it direct into Kdenlive.

Many thanks for your description and help.

BTW: In which program do you create the Kdenlive “flag” logo?

Hi Merlimau,
cool to hear it works...
The logo was created in blender which forms with kdenlive and gimp my most favoured applications in Linux ....