Hi everyone. Not sure whether this goes in here or bug reports, because I'm using old versions of... everything, and I'm a Linux noob. :)

I'm running v0.7.5 on an Ubuntu Karmic-based live CD. The problem is that the clip monitor plays back smoothly with an Intel Core 2 (2.4 GHz) with a load of 20%-30% split across both cores. That computer has an Intel GMA 3000 adapter. However, on my Intel Core i5 (4 CPUs, 2.26 GHz) with an ATI Mobility Radeon HD 5740, video playback for the same video is extremely choppy with a load of 10%-20% for each CPU, so totals easily reach above 40%. Audio playback is okay in both cases.

Does this have anything to do with hyperthreading support, and if so, is it resolved in later versions? I'm also open to other suggestions. My main worry is that the problem will persist even if I set up a dual boot and use the newest version, because if I use the dual boot at all it will be for kdenlive. :)

Thanks in advance.

Not sure. I suspect it might be more a factor of the video card than the number of CPUs or hyperthreading.

Could be that. The first computer has 256 MB total graphics memory and no dedicated video memory, compared to the second computer's ~2 GB and 512 MB respectively... Of course, with the second computer I have to turn off hardware acceleration to get the monitor to play at all.

It's slightly frustrating because the second computer has, objectively speaking, better specs. Also, it's a laptop, so I can't change much about it. :\ There are a few other computers I can use for testing. What would you recommend?

What exactly is "turn off hardware acceleration?"

Change the video driver used for playback in kdenlive from Automatic to X11. It was recommended here for blank clip monitors, which I had earlier: http://www.kdenlive.org/user-manual/troubleshooting-and-common-problems/clip-and-project-monitor-only-display-still-images-a

Of course, I'm not sure now that I did it correctly, but at least the monitor isn't blank.

Ah, well, that explains your choppy playback. Your ATI X11 driver does not support XVideo, which is needed for high throughput video output, or perhaps its XVideo does not work in conjunction with some desktop environment that is using OpenGL. You can try disabling the 3D desktop effects and see if the Automatic or XVideo setting in Kdenlive works better.

Thanks. :) I'll try that out.

Disabling desktop effects from System Settings > Display has no apparent effect (in any case that setting seems to be off by default). Automatic is still blank, X11 and XVideo are still choppy (but I think X11 worked fine for a while before becoming choppy. In fact the problem always seems to worsen with time). Disabling both that and visual effects under Appearance gives choppy playback for everything. I'm wondering if I might be mistaking very slow playback for the error requiring the driver switch. That aside, I have been getting crashes but I can't consistently replicate them.

ETA: Playback is okay on another computer with an ATI Radeon HD 4330. It also runs Cinecutie without problems, when it crashes without fail on the machine we are discussing.

ETA2: Kdenlive 0.7.8 on an external hard drive is okay. Can't expect too much from an old version, I guess, so thanks very much for your replies. :)

The video player option in Settings is only used when you choose to play the video after rendering it. It has no affect on the clip or project monitors, which must use MLT.

Just my $.02 here...I had this issue as well, even using the latest stable release (0.7.8). What I found was my default project type was a very high resolution project (1080p, I think). In reality I was not going to render the project to that level, was going to render to basic DVD quality. When I changed the project to DVD quality the choppy playback stopped.

So what I assume is happening is kdenlive is trying to play the clip/project at the resolution defined when the project is created. So in my case, my computer just couldn't keep up with playback at 1080p.

Now that brings me to a question and possibly suggestion:

First, is my assumption correct? Is the playback quality the same as the final project render quality?
Second, if the first is true, might it be possible to have a setting in kdenlive that would allow the playback to occur at a lower quality but rendered at another? Or is that already there and I just don't get it?

> First, is my assumption correct?

yes

> Is the playback quality the same as the final project render quality?

not exactly. The clip/project monitors use reduced quality levels for scaling and deinterlace.

> Second, if the first is true, might it be possible to have a setting in kdenlive
> that would allow the playback to occur at a lower quality but rendered at another?
> Or is that already there and I just don't get it?

It is in the next release in the form of "proxy" editing.