Images and Windows Movie Maker


[Article updated Apr 26th 04 to show how to create a video file that is more than one frame]


A few weeks ago, in the Windows Movie Maker newsgroup, there was a thread about images and what size they should be created at to work optimally without being resized.


At first glance it’s a simple topic but as there are several things to bear in mind when adding images to the Windows Movie Maker timeline I thought the subject warranted further comment.


(For the purposes of the following conversation I’m going to assume you’re using 4:3 NTSC, but for those PAL folks just pretend I’m saying 720 x 576 everywhere I say 720 x 480).


If you’re publishing video from Movie Maker to put onto a DVD or send back to a DV camera you’re probably going to render it out at a resolution of 720 x 480.


You’d probably think therefore that if you want to create an image to add to that video you would create it at 720 x 480. Couldn’t be simpler? However unfortunately that probably wouldn’t create the result you’re looking for.


The problem is that images, by their very nature, contain square pixels and when you’re creating NTSC 720 x 480 video, that video is actually composed of frames that contain non-square pixels. Movie Maker knows that images contain square pixels so if you give it an image of 720 x 480 it will assume that the image has an aspect ratio of 3:2 (720/480 = 1.5 which is a 3:2 aspect ratio). As you’re outputting 4:3, Movie Maker will add black bars at the top and the bottom to preserve the aspect ratio of your original image. You can see this below in the image of the preview window when it is previewing a 720 x 480 image that I created in Microsoft Paint. Note the black area below the 720×480 text at the top and the area above the Paused text at the bottom.


 


(If you want to try this out yourself I’ve included the images I used in this article at the follow location ImageMovieMaker.zip)


To fix this problem you need to give Movie Maker an image which matches the aspect ratio of the video file you’re trying to output – 4:3 in this case. If you get out your trusty calculator, you’ll find that your best options are going to be 640 x 480 or 720 x 540. These image sizes both have an aspect ratio of 4:3 and Movie Maker will only need to resize one of the axis as the other one matches the target output.


Here’s a preview of a 640 x 480 image and you can see the black bars are no longer present. You would get similar results with a 720 x 540 image.



Problem solved. This is probably good enough for most cases. However some of you may want to include images with text or lines that may not resize well. You’re probably wondering if there is anyway you can tell Window Movie Maker not to resize your image.


Well there is a way. If you convert your image to a video file then Windows Movie Maker will no longer assume the file contains square pixels and the frames will not be letterboxed.


So how do you convert an image into a video file? This is easily accomplished using the Windows Media Encoder. If you don’t already have it installed you can download a copy from the following link


Windows Media Encoder 9 Series


Launch the Encoder and in the New Session window that appears select Convert a File. 


On the next page click browse and choose your image, it will then default the output file to a suitable WMV filename but you can change it, if you so desire. Click Next when you’re done.


Choose File download (computer playback) from the next window and click Next.


On the Encoding Options page there are a bunch of pre-defined choices, just choose DVD quality video (2 Mbps VBR) and click Next.


On the Display Information, you can specify a Title, Author etc. for your WMV file, but you don’t really need to, so just click Next.


On the Settings Review page, turn off the checkbox that says “Begin converting when I click Finish” as we’re going to do a little bit more customization. Then click Finish.


Now the wizard is closed, select Properties from the toolbar. From the Session Properties window that appears, select the Compression tab and then click the Edit button.


Change the video mode to Quality VBR. Change the video format at the bottom to NTSC or PAL depending upon your target destination. Here’s my screen.


Now switch to the Quality-based tab and click the “Same as video input” checkbox to check the option. While you’re here also change the Video quality to 100 and click OK and then Apply.


[New section Apr 26th 04]


To ensure you create a video that is more than one frame long, (useful it you want to drag the file to the timeline 🙂 ), go to the Output tab and click on the option labelled “Pull from encoder (the connection is initiated by the server or players)”. This will cause the encoder to keep the single image as the frame that is being published as long as the file is being encoded.


That should be it so click Start Encoding on the toolbar. Once the Elapsed time: has counted for as long as you want the file, click Stop Encoding. You should now be the proud owner of a WMV file containing your image. (I also included the WMV file I created in the above mentioned zip file).


You can now import that file into Windows Movie Maker and it shouldn’t be resized so you shouldn’t see any black bars at the top or bottom. Here’s what the preview of the created WMV file looks like when I preview it in Windows Movie Maker. Notice that the black bars are no longer there.



There is another thing to notice in the above image. If you look at the circle you’ll see that it is slightly stretched vertically. This is because when I created the original image I assumed I was going to create an image with square pixels and now we’re treating it as an image with non-square pixels. If you using a package like PhotoShop to create your image you can tell it that you’re creating an image with non-square pixels so that you can preview the image with the correct aspect ratio.

Comments (13)

  1. Rehan says:

    Hi Dean,

    Its good to see this covered here. I am not sure about 720×540 size you mentioned above. I think only 640×480 size will be able to avoid the resize operation.

    This is based on the observation while debugging my custom plugins which seem to always get a frame of $:3 ratio, for both output sizes of 640×480 or dv avi 720×480. Note that: even when the output is DV AVI 720×480, the frame presented to the custom plugins is 640×480.

    Fromthis I gather that there are two resize operations involved. One that happens at the very begininng in the pipeline to make input to be same size as output. The other resize is done by the encoder at the final encoding stage due to the profile used. I think the reason for the first resize is to avoid any resizing to happen at the encoding stage.

    So when input=640×480 and output=320×240 => only first resize would happen.

    when input=640×480 and output=720×480 => first resize won’t happen but the encoder would resize using non-square pixel encoding to fit the frame to 720×480.

    When input=640×480 and output=640×480 => no resize would happen

    When input=720×540 and output=720×480 => both resizes happen: first makes the frame fit 640×480 with black borders, present this to the custom plugins and then the encoder finally stretches the output to 720×480.

    Therefore I would argue that to avoid any resize of still images one must use input images of size 640×480 and a WMV prfile for output with size 640×480.

    Which makes DV AVI to be not suitable as the profile to be used for outputting a still slideshow as it would always cause the second resize operation.

    Comment please?

  2. Rehan says:

    Please read "$:3" to be "4:3"

    and

    "with black borders" to be "without black borders" in



    When input=720×540 and output=720×480 => both resizes happen: first makes the frame fit 640×480 WITHOUT black borders, present this to the custom plugins and then the encoder finally stretches the output to 720×480.

  3. Dean Rowe says:

    Thanks for the comments Rehan, I’ll check into the multiple resizes with plugins and report back.

    Cheers

    Dean.

  4. amanapart says:

    I think I followed your instructions, and I certainly ended up with a very small .wmv file.

    However, when I try and import (as video) this into Win Movie Maker I end up with a .5 sec clip. How do I get it to sustain for 3-4 secs?

  5. deanro says:

    An excellent point :-). My original instructions only created a video file that was one frame long, which isn’t that useful if you want to use it on the timeline. I’ve now updated the instructions so it will create a video file for as long as you need. Hopefully this will be a little more useful. See [New section Apr 26th 04] in the entry.

    Cheers

    Dean.

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