Hi

Not long ago I updated to the 15.04 version from kdenlive 0.9.10. I immediately noticed that this version is unstable and has some serious problems.
I can't preview a H264 encoded mp4 file because the Project Monitor is flashing in some weird green purple colors and shows slow slideshow. Audio is often choppy too.
In an other project, the preview stops for a sec at every clip cut. When making a project with some basic clips,images,effects,titles and transitions it always crashes. I think this might be a major problem with the fonts. These are the biggest problems, all in all the new kdenlive is very slow and doesn't seem optimised not a little.
So I found this forum and opened this topic hoping that somebody knows the reason why kdenlive 15 is an unusable sh*t for me. This program is very important for me, I could not ever found a better video editor not even on Windows. I didn't want to use the bug report system because this is not a specific bug.
I reinstalled the application and melt several times. I am using ubuntu 15.04 with jackd2 and pulseaudio with pulseaudio-module-jack. I want to move to Ubuntu Studio soon.
I have no idea what should I do about it, found nothing in settings and google, and as I said everything worked very very well before.
I am helpless and I need this program to work asap.

I don't know if this is the right place for this but if you can help please let me know.

I thought I revert to kdenlive 9 but I don't know how, because the default kdenlive version is 15.04 for ubuntu 15.04

What resolution of video are you trying to edit ? Is it HD?
Do you have proxies turned on. You should try it with proxies on.
See this thread for a similar example to what you describe
viewtopic.php?f=265&t=127677&p=340279&hilit=proxies#p340279

check installing from daily builds here
https://userbase.kde.org/Kdenlive/Manual/Installation

it worked for me pretty good , so i have a 15 version and the old stable one running on the same computer.. not sure if this works with ubuntu though, but you should give it a try