Hi,

as I mentioned in other threads, I'm quite happy with vdpau on my old and cheap hardware. I'm editing AVCHD content and the playback is smooth.

However, searching is rather poor, and when it comes to effects applied to the scenes, the system also comes to its limits. One more point is a short delay that occurs between two scenes when playing in kdenlive what I edited.

So, my question is: What's the typical bottleneck? Do I need faster access to my files (I have average SATA HDDs) to get rid of the delay between two scenes? Then a small solid state disk should do the job. Or do I need more memory (I have 1,5 GB) to keep more content im memory? Ok, I could throw in another Gig. Or is it mostly the computing power in the CPU (although pure playback in smplayer is under 10% CPU usage)?

Maybe the experts could give me a hint.

Thanks!

Chamo

The seeking bottleneck is inside ffmpeg, and the solution is not easy while also not causing a regression elsewhere.
The processing bottleneck requires parallel-processing, which has been in development for most of 2010 and hope to get public by end of year.

So this means that there's no point in getting better hardware at the moment. I can stick with my old and cheap box.
Let's come back to this question when the software has made the progresses that you mentioned by the end of the year.

Thank you for your fast and solid answer - and for all the work you've done and you're doing for these projects!

Cheers,

Chamo

Hi,

it's been quite a while since I tried to maximize performance. I just worked with what I had. Now I couldn't help but get some better hardware. Much better, actually. But I'm surprised to see that the performance it pretty much the same as before.

Regular playback is smooth, but it gets sluggish as soon as an effect (e.g. colour correction) is applied (I guess because vdpau is not available with effects).
Every change from one scene to another stops playback for a moment (like one second).
Jumping to the middle of a scene still takes a few seconds.
Searching back is a pain (like one or two seconds per single frame).

I had a look at the system load and this is what I observed:
1) One CPU core goes to 100% when playback of a scene starts, then after a few seconds goes to 80%. Playback is smooth, and the other CPU cores are more or less idle.
2) When one scene ends and the next starts (without any transition effects), then CPU load drops to 0% while playback stops. Afterwards, see (1). This looks like the CPU is waiting for data to process.
3) When an effect is applied to the scene then one CPU core goes to 100% and stays there, the others are still idle. Playback is sluggish. (I expected this.)
4) It looks like the swap space is not used at all (I have 4 GB of RAM)
5) I can't see any significant read access or data stream from the hard disk. Sounds unrealistic... Maybe my tool just fails on this.

Now, can I do anything to improve performance? It just looks like nothing on my system is fully loaded, but there MUST be a bottleneck somewhere!
Any hints?

(BTW, when rendering, one CPU core goes to 100% and the other ones are below 10% although I allowed 4 threads. Is that expected?)

Thanks for your support!

Chamo

Hi Chamo,
assuming, your are still editing AVCHD content, you may want to use proxies. When setting up your project you can activate them (since 0.8.1) and you will work with a lower resolution copy of your AVCHD files. When it comes to rendering, the original files are used.

Hi al25fps,

thanks for the suggestion.
I checked the box for proxy clips (with an existing project), but I can see no difference at all.
When is the low resolution copy supposed to be created? Only at adding new clips or also when I configure proxying later?

Still, I really wonder why this high end box (8 CPU cores, 4 GB of RAM, everything good stuff) behaves just the same as my old single core Athlon with 1,5 GB of RAM. I mean, it just doesn't make sense that nothing in this box is fully loaded while I have to wait for the searching inside the scene... That doesn't sound logical.

Chamo

Hi Chamo,

I don't understand why you can't get Proxies to work. A quick scan from the above, you don't say what distro you are using and which version of Kdenlive.

Now, without Proxies, I would not even bother to try working with AVCHD clips. With Proxies, clicking around the timeline is almost instant.

I love al25fps' description of the bottleneck, it's really good. Thinking about it, you can't imagine what Kdenlive is trying to do in 'real time' when it's reading a dissolve transition and at the same time changing every pixel of a frame under colour correction all at say, 25fps. Must be almost impossible, but the render is cool.

As al25fps says, if you are still using AVCHD content, it's a must to sort out your Proxy problems.

Hi Chamo,

I still shoot my projects in SD and do not use proxies. I am sorry, but therefore I do not know, if the proxies are created only when adding a file to a proxy-project or by selecting the checkbox in an existing project. There are some threads about the proxies around here. :)

I guess you will see a difference in the hardware, when it comes to rendering. That the preview does not look better is caused by the compression of your source clips, which does not support fast seeking. It is and stays the bottleneck. Imagine a traffic jam during rush hour - it does not matter if you drive a slow car or a hyper sports car, the speed you go is given by your environment, you cannot go faster with a faster car. But on the highway (or while rendering) you will enjoy the power of a sports car.

Cheers and good luck