Kdenlive Render Runs at Snail's Pace

[NoWorries]

On my new Laptop I have Kubuntu 18.04 (Bionic) and 18.10 (Cosmic) installed. I have Kdenlive installed on both and the version on Bionic is 18.04.1 and on Cosmic it is 18.04.3.

Ever since I have been using Cosmic, I have found that using Kdenlive to render a video takes so long that I give up testing it. The video I am using is 23min long. Updates have never corrected this problem so I have now decided to quantify how bad it is, so that something can be done to fix this problem.

When I use Kdenlive to render the video file on Bionic it takes 1hr 16min. I have the same files on Cosmic, and the render process I calculated after a couple of hours of rendering. I used the time that I started the rendering and added it to Kdenlive's predicted finish time. This approach predicted it would take 9hrs 30mins. In frustration I decided to actually wait until it finished. The rendered video worked well however the time I measured was 10hrs!

My current system status is shown in the graphic below.



I don't think the problem is with the Kdenlive source code, but in the way it has been built for Cosmic. I hope this problem is easy to fix.

[GreyGeek]

Just curious as to how the appimage ( https://files.kde.org/kdenlive/relea...age.mirrorlist ) version will run on your box.
To install, just download the file and make it executable, ( chmod +x ) in a terminal, then run it. No need to unzip it. If you don't like it just delete it. Nothing is changed on your system.

I use appimages for 16 of the apps that I use. Nary a problem.

[claydoh]

Probably the encoder backends in 18.10 are in flux or something, specifically ffmpeg and MLT. The appimage is for a slightly older version than in Cosmic, the same version that is in Bionic, so I bet it Just Works.

I'll guess that reporting a bug on this is not appropriate this early, but worth it if it persists. No one involved with Kdenlive will see it if it is only posted here.

[NickStone]

What format are you rendering the video to? I mean, are you rendering it to a HD format or simple DVD format? What profile are you using when editing / rendering the video?

I use kdenlive (version 18.08.0) as well and I believe the default profile is in HD format and when I tried to render it would take approx. 4 hours or more. As I edit video's to put on to DVD I chose the DVD profile when editing and rendering videos which usually takes on average 45 mins (depends on the length of the video).

Anyway, check the profile. I would only render it to a HD format if your going to watch it on a HD screen, otherwise I would use a lower resolution format.

[NoWorries]

I render to an mp4 file and the render that I use is shown below.



A section of the video that I am rendering is shown below.



I have found that melt is the main culprit. It starts out using about 20% of the cpu but this drops to about 8% or less not long after and this is the time when the predicted time goes to multiple hours, like 6hrs or more.

I guess I have been conditioned by my 6 year old ASUS R501VM N56VM Laptop which completes the render of this file in about 45 minutes!

While I am doing this post, a render is happening at the moment and it is rocketing along unabated. I will let you know if the updates have fixed this problem.

[NoWorries]

The render which originally took 10hrs was now completed in 32min!!!

I was doing other activity while this was happening so it could have done in 31min if the render was the only activity. To make sure this is consistent, tomorrow I will try another more recent render to check that it is consistently fast.

I have to deal with M$ lovers who in some cases wait overnight for their render to finish. I have the reputation of creating a record for getting a rendered video posted. With this speed I will be able to make a new record to challenge the M$ lovers.

[NoWorries]

I have now checked out the Render step with a recorded video which has been edited and the length is 13min 2sec. My 6 year old ASUS R501VM N56VM Laptop did it in 32min 24sec. My HP Laptop did this render in 20min 9sec.

So the updates have definitely improved the Render speed out of sight! A job well done and thanks to all those who fixed this problem so quickly.