[kdenlive] Reduce mem usage while rendering

[Jean-Baptiste Mardelle]

On Sunday, March 27, 2016 11:12:32 PM CEST, Dan Dennedy wrote:
> I am working on a MLT bug report: "melt eats more memory than available"
> https://sourceforge.net/p/mlt/bugs/242/
>
> It is still not yet clear if this large and complex project 
> simply requires much memory, or if there is a leak. However, my 
> suggestion to alleviate the problem can be considered 
> successful: add "autoclose=1" to each MLT playlist when making 
> the render XML. I have known about this for some time, suggested 
> it in the past to users, and recently I added it to Shotcut. It 
> is documented here [1]. The memory saving is not always dramatic 
> as this particular case, but at least it will save many people 
> from having a problem while rendering from the GUI - both of 
> which can be memory hungry. Also, it might be a good, easy 
> improvement to add to Kdenlive.
> [1] https://www.mltframework.org/doxygen/properties.html


Thanks Dan, 

I applied this fix. 

By the way, that might not be related but in Kdenlive we use a playlist to 
hold our project clips, like you do in Shotcut with the "main bin" playlist 
and there also seems to be memory issues with clip management.

Open Kdenlive, empty project. Memory usage: 92Mb
Add a 19Gb clip to Bin. Memory usage: 520Mb
Remove clip from Bin. Memory usage: 502Mb

Memory is not freed after deleting a clip from bin.

Same thing happens in Shotcut. When adding a clip to the playlist and 
deleting it, memory is not recovered.

I noticed this several months ago and I think with older Kdenlive/MLT 
versions, memory was freed when deleting a clip... in case it can help with 
your investigations...

regards
jb