Hi guys

I use Kdenlive on a regular basis. Several times per week I wood say is an average.
So I also see and follow the developments kind of closely.

I have a question concerning the proxys(proxies?) and the 'rendering' of proxy clips with a 4-core machine(without HTT).

Prior to the proxy clips I used to transcode and if I wanted to transcode several clips I could start the transcoding of the clips in independent processes.
That would take advantage of all the cores, and my 'system monitor' would tell me that it was using 100%*8(4).
As an example, I could have 12 transcode-windows open transcoding different clips and that would use all cores. As clips finnished rendering it would of course use less than 100% of all cores.

When Proxys was introduced it did that automatically, starting creating proxys but as if the proxy-rendering was started independently for each clip.
My computer would be kind of slow during this time, but I was able to get the proxys ready very quickly.

Now it seems like the proxy-rendering only uses one of my cores, leaving all clips standing in line behind each other.
Like everybody going to the supermarket and only creating a single line in front of one cashier, in stead of using the other cashiers ones which are also so open.

Can I change this?

The video-editing I do is almost allways news-based(e.g. a demonstration etc.), and it is quite often that when I come home, I bring some food, transfer my clips to the computer and leave it to create proxys while I e.g. eat or have a cup of coffee, so while eating/drinking I would Kdenlive to take advantage of all the nice cores I've paid Intel a lot of money for ;-)

I'm not an expert and I can understand that there is a big question on how to take advantage of severwal cores in one sole rendering-process, but this is kind of different I think, it should be possible and it was possible at a point in the development.

Here are my numbers:
I7-860 4x2,86GHz
12 GB DDR3-ram
1000GB HDD 7200
-
Ubuntu 11.10 64 bit
Kdenlive 0.8.3

My English is not perfect...

Does anyone has an idea of what I'm talking about?
Or do you have similar experiences?

I think kdenlive spawns two ffmpeg instances per detected core, the number can be controlled in kdenlives config menu. There was a problem with crashing relating to HT a while ago but was fixed.

Have you looked at your system monitor when building proxies to see what happens?

Ok, think I've found it in 'configure kdenlive'.
In 'Environment' I can choose how many concurrent threads used for proxies.
Don't know whether default is 1 thread(as mine was set to) or whether I might have changed it along the way.
I'll try 6, it is a nice option to be able to choose...

Thanks

It worked.
6 threads are creating proxies while the latter two are 'free' for other use.

Default was set to 1 for safety due to earlier issues including with HT.

Ok, but are you sure we're talking HTT here?

When I render a video, I usually just set it to 1 thread, haven't experimented to much with several threads yet.
That would be HTT I guess, one process, several threads.

But when creating proxies I imagined it was like 'one proxy in creation per thread'.
I guess you could call it HTT as well, but I just saw it as Kdenlive started processing each clip, and that it did not start processing '10 clips' in a row as one process.

My default for rendering videos is still 1 thread.
Kdenlive calls it 'concurrent threads' when creating proxies.

What are your experiences on using several threads on rendering videos?

To clarify I was just talking about proxy generation, not rendering in general. As a layman myself I'd assume any multithreading / multiple core use is encoder implementation dependant and not at kdenlives control where as spawning more instances of ffmpeg for proxy generation is different.