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problems with image clips/photos

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Gingerling
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problems with image clips/photos

Wed Jun 05, 2013 11:55 am
Hi, I have a very annoying problem, its been plaguing me for ages but I haven't had time to understand it.

Here is a description with screenshots: http://blogs.fsfe.org/anna.morris/2013/06/05/kdenlive-image-clips-always-wrong-size/

To summarise, I am struggling to get kdenlive to show image clips without a black border around them - even if i try making images the same size as my project. It seems to be scaling them somehow. Sorry I am struggling to explain this, I made the blog to explain it using images as its easier - please take a look and let me know what I can do to

a) make an image clip in gimp that will show full screen (even if the project has a diffrent video size - what is "the rule" here?)
b) if there is some setting I can tweak in kdenlive to change the way it imports image clips
c) if this is a bug at all

Best

Anna

yellow_drupal
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Re: problems with image clips/photos

Wed Jun 05, 2013 12:13 pm
The problem you have is to do with pixel aspect ratio. Formats like HDV and DV use non square pixels.

In Gimp you need to use a 4:3 pixel aspect ratio rather than a 1:1 PAR. Then when 1440x1080 is stretched to the 1920x1080 HD resolution a circle drawn in gimp with a 4:3 PAR will look right.

I'm not sure why you are using a HDV project profile unless your source videos are HDV.
Gingerling
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Hi, that was just whatever was set when i opened for the example, but I nearly always go with what kdenlive suggests. My camera is a new pentax dslr, and I still have that problem in projects set up for that. Are those pixels square?

Thanks for the help

Gingerling
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Hi, here are some further elaborations http://blogs.fsfe.org/anna.morris/2013/06/05/kdenlive-image-clips-always-wrong-size-part-two/

I would like to understand how I can deal with this problem, what size image i need to make to avoid it in various profiles, and why kdenlive deals with images of the "wrong" aspect ratio in the way that it does and if there is a better way that is easier for people in my position :) I am happy to write a manual on this topic once I understand the issues involved well enough :

Anna
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j-b-m
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Well, from your example you are using an HD 1080p project profile. This means that Kdenlive will work with frames with a 1920x1080 resolution.
Then, it is normal that adding a 1080 x 1440 pink clip, you will get black bars (unless you made a typo in the resolution).

Can you tell us exactly what size are your image & video clips so that we can figure out the problem?

The resolution of your images and video clip can be found in Kdenlive's clip properties by double clicking in the clip in project tree.
yellow_drupal
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Hi, your Pentax DSLR will be 1:1 PAR for video, photos of coarse will always be 1:1 PAR. Display or Screen Aspect Ratios may vary though.

"Re: problems with image clips/photos

I would like to understand how I can deal with this problem, what size image i need to make to avoid it in various profiles, and why kdenlive deals with images of the "wrong" aspect ratio in the way that it does and if there is a better way that is easier for people in my position :) ..."

The 'display' aspect ratios used for photos and videos vary due to the differing origins of the formats and the history. What particular manufacturers choose to offer us as formats and ratios is based partly on hardware, a DSLR will provide ratios for photos of a still camera, a mobile phone camera may provide resolutions associated with a computer screen like 640x480 (4:3), a HDV format video camera a 1440x1080 HD non square pixel output because of the limitation of firewire bus to be able transfer any higher resolution.

If you want a photo shot with a different aspect ratio to a video to be combined into the same project you'll need to crop one of them. :-) Scaling an image unequally in the x or y will cause distortion, so crop or pad.

Padding can be done various ways but generally by adding black pillar boxing or letterboxing to make up the frame size and aspect ratio.

Out of interest which Pentax do you have?

Mediainfo is a good tool for giving you a bit more info on your files to help determine project type and format based on your source media.


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