Having some problems getting the desired target video size [resolved]


I'm trying to render a simple video that should be 1024x768 in size. My target viewing platform is WindowsXP Embedded on a thin client machine with screen resolution of 1024x768.

The video needs to loop forever in full screen and the best player I have found for this is MPlayer built for Windows.

I'm running kdenlive on Ubuntu 12.04

My Render settings are:
Custom Size: 1024 x 768
Frame rate 30000 / 1001
FPS 59.94
Pixel aspect ration 8 / 9
Display aspect ration 4 / 3
Colorspace ITU-R 601

In the render dialog:
XVid4 is selected (but I've tried others with no better success)
Scanning is Auto
Encoder threads is 1
Export_audio, 2 pass, Rescale, Play after render and overlay are all unchecked.
Full project is selected.

The line that is built in the render dialog is:
acodec=libmp3lame ab=%audiobitrate+'k' ar=44100 vcodec=libxvid minrate=0 vb=%bitrate+'k' aspect=%dar mbd=2 trellis=1 mv4=1 pass=%passes

The resulting video .AVI file reports that the video is 1024x768 when looking at the video properties.

But when I play it on the target device with display resolution of 1024x768 the video does not fill full screen in Mplayer full screen mode. It has a fairly large black frame around it.

If I use another custom project profile and increase the width I can get rid of the black on the sides of the video but not the top and bottom.

I found a discussion about using crop with center checked but that didn't actually solve the issue for me.

I suspect that it has to do with the aspect ratios, but I'm not sure how to adjust those to achieve what I need to do. And I'm not sure why I should have to since the video should be rendering to the full size of the target display.

What am I missing?



Some additional information:

I went back and looked at the source image file. For this test I'm using a static image, and there will be other static images as well as some video clips involved eventually. But right not just a single static image that was sized at 1024 x 768.

With that image I was getting black bars top and bottom in the project preview. I thought that the project size was set at 1024 x 768 but apparently that is not the case or I'm missing something. I made the image larger in the vertical.

But still had black bars top and bottom. So I did the Scale and Tilt effect. I scaled Y and that filled the bottom but still had the black bar at the top.

I then changed the tilt Y value and that shifted the image up in the project view. I then rendered with my custom 1024 x 768 profile and the resulting video now fills the 1024 x 768 target just fine.

Did I miss something with the project size setting somewhere that actually makes the project frame larger than 1024 x 768?


Pixel aspect ratio should have been 1:1 rather than 8:9 ?

I'll try that. I'd based it on a similar existing profile.

But the main issue appears to be that even though I believe that I have the profile set for 1024 x 768 and the resulting video properties show that the image file clip I start with doesn't appear to fill the frame.

As mentioned before the image was at 1024 x 768 and the profile was set to 1024 x 768 but looking at it closely the frame displayed in the project view had the black areas top and bottom. But the entire image clip was present as all text was viewable in the project view.

When I applied the effect to expand Y and then "tilt" Y I was able to get the image clip to fill the entire frame in the project view. Then rendering gave me the desired result.

But I want to understand why the 1024 x 768 image clip did not fill the frame in case I missed a setting somewhere.


If the PAR is non square then there will be stretch or squash in vertical or horizontal as pixels are not square but for 1024x768 I assume for monitor display they should be square 1:1 PAR not 8:9 ratio. When you say you have letterboxing are you sure kdenlive or whatever you're viewing on is not also scaling to make it fit horizontally on screen perhaps?


Since the letterboxing appears in kdenlive and when I scale and tilt in kdenlive I can get the rendered 1024 x 768 video to file the screen on the 1024 x 768 output device I'm assuming that the issue is something to do with how I'm setting up the project in kdenlive.

What I'm trying to determine is if there is a setting in the project somewhere that I'm missing that will eliminate the letterboxing of the clip image in kenlive for this example? That is something in addition to the project profile setting that will tell kdenlive that the frame size is 1024 x 768 so it does not letterbox the image clip. It appears that the project profile that I have set does control the rendered video size (e.g. 1024 x 768) properly but it doesn't appear to be controlling the frame size within kdenlive, at least in this case.

Now that I know that scale and tilt will resolve the issue for now I can use that approach, and if that is the only way to resolve it then I know I can use scale and tilt in similar cases.

But I would prefer to not have to do that.

Thanks again,

Your project details from your first post state a Pixel Aspect Ratio of 8:9, not 1:1 so the pixel's are assumed not square but your display device is square pixels. You could try creating a project profile again and setting PAR to 1:1 and see if that solves it for you.

Using your current project settings your video file will be telling the media player that the video is not 1:1 PAR because you used 8:9 ratio in your project profile, so on play back that will be compensated for by stretching or squashing the assumed non square pixel nature of your source file so that it 'does' display correctly on a computer monitor because that does have a 1:1 PAR, inevitebly letterboxing or pillar boxing will be added by the playback device to fill in the unused screen space.


That did indeed appear to correct the issue in the kdenlive project view and the rendered video also appears to be fine. It actually did not appear to be the player that was letterboxing. It was being letterboxed in the kdenlive project view and the resulting rendered video was actually letterboxed regardless of what player I was using. The resulting video was showing 1024 x 768 but the contents was already letterboxed.

Changing to 1x1 pixel aspect ratio corrected this.

Next up, for a different project I need to see what PAR I will need to use for the Optec LED sign that I'm having to do a video for. The information provided didn't list the PAR so I'll have to experiment with it unless I can track down some details.

Thanks again,

I'd go for 1:1 without doubt. :-) Good to hear your other problem is solved.

I did a test with 1:1 for the Optec sign and that also appears to be a good choice.

Thanks again for your help.

burtbick; good to see that's solved,
can you change the initial post title to add some [solved] ? thank's