Volume effect work in preview but not after rendering

Ubuntu 10.10 with kdenlive installed using the repository from ppa sunab.
If I use the volume effect to decrease the audio level, putting it for example at 50 it works ok in the preview but when I export the video the audio is just muted.
Indeed if I increase the volume effect when I export I can hear the difference but it is minor than in the preview.
Changing the export codec does not make any difference.

Any suggestion are really welcome, this is the only problem I have with kdenlive but it is very annoying!!
Francesco Lodi

Some new information: today I have tried to install kdenlive from source, in order to be sure that I have all the dependencies.
Compile was ok but the problem still remains. I have also tried kdenlive from svn.
Whenever I use the volume effect under 100 in preview work all ok but after rendering the audio is muted.
If I launch kdenlive from console I can see ths output when exporting:

//STARTING RENDERING: true , false , "/usr/bin/melt" , "atsc_1080p_25" , "avformat" , "-" , "/tmp/kde-francesco/kdenliveMg9281.mlt" , "/home/francesco/Video/test.mp4" , () , ("f=mp4", "acodec=libmp3lame", "ab=128k", "ar=44100", "vcodec=mpeg4", "minrate=0", "b=2000k", "aspect=@16/9", "mbd=2", "trellis=1", "mv4=1") , -1 , -1
Started render process: "/usr/bin/melt" "/tmp/kde-francesco/kdenliveMg9281.mlt -profile atsc_1080p_25 -consumer avformat:/home/francesco/Video/test.mp4 progress=1 f=mp4 acodec=libmp3lame ab=128k ar=44100 vcodec=mpeg4 minrate=0 b=2000k aspect=@16/9 mbd=2 trellis=1 mv4=1"

this was for a MPEG4 but the problem remains with every codec I use.

Please help!
Many thanks,

After many test I have found that the problem only happens when I put on the timeline a title that have inside a png image. If I convert the png to jpg it works ok.
I hope that this can help someone and that you can correct this little bug because using png is very usefull in order to have images with transparencies.

> After many test I have found that the problem only happens when
> I put on the timeline a title that have inside a png image.
> If I convert the png to jpg it works ok.

Now that is very strange. A PNG in a title breaks the audio volume but only when rendering? WTF? Sorry, I could not reproduce it. Maybe some memory related to the volume effect got stomped on, but locating that bug is like finding a needle in a haystack if I can not reproduce it.

I was also very puzzled by this bug report.

But as reported here:

There is a bug affecting the QImage producer when using indexed or mono PNG files. Maybe it corrupts MLT and created the problem. Could you send me one of the problematic PNG file (jb at kdenlive org) so that I can check if that might be the cause?

I have a patch for the QImage producer ready but want to make some more tests.


Hi and thanks for your time.
The simple attached png broke the rendering but I have found this problem with every png I have created with Gimp.
If I can be helpful I would be glad to do some test for you.


Any update or workaround?

I faced same problems with Volume Effect: random rare crashes (when seeking in timeline) and most important when volume

Opening the program it works ok. But just playing some parts (I think with png images) then it starts to works bad. The same even if I run immediately encoding.

The images are .svg with alpha channel, .png and .jpg and are correctly shown and encoded.
Now I'll try to convert them in gif format.

Kdenlive version: both 0.7.8 and svn (0.7.9).

ps: it seems that recent svn releases (with libmlt3) don't open correctly old kdenlive files. Maybe something changed in xml handling. It's a feature or a bug?

EUREKA! (almost for me :)

Ok, I must admit, in my case images are not related.

The problem is with the "declipper" filter. I've used it in a clip and I've noticed that after playing this clip then the volume effects doesn't work fine.

May be a conflict with ladspa library?

hope this helps you

I tried to reproduce by putting the volume both before and after the declipper and rendering to MPEG-4, but I was not able to reproduce it. Sorry.

If I'll find the time, I'll try to package a test case for you.

Can you suggest us what's the best linux distribution in order to run kdenlive (svn) version?

I think I'll add a dedicated S.O. partition in order to run kdenlive without "strange" problems.