Square Pixel
- At August 5, 2009
- By ken
- In tech / video
I was asked the question the other day about square pixel format and my motion graphics workflow. Here’s the 4-1-1 on my file format workflow, and why I’ve chosen it. There may be other opinions, but over the past few years (at least in the world of SD), this is my preferred method.
Square Pixel widescreen. When creating a comp in After Effects, I choose the “Square Pixel Widescreen” preset. It gives you a frame size of 864 pixels wide by 486 pixels tall.
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Every computer monitor I use is a square pixel monitor. Video output, however, is not square. For wide screen (16:9), the pixels are actually wider than they are tall. The aspect ratio is 1.2. A computer monitor cannot resolve the non square ratios. When the final image is rendered it looks fine, but when you’re crafting the piece you have to deal with what is referred to as aliasing.
Example of aliasing
[photopress:al.png,thumb,pp_image]
See those jagged edges, especially along the angles of the A? That is aliasing. When rendered and shown on a TV monitor the edges will go away. But when you’re working on it, you have to contend with that visual nastiness.
After Effects does include this little switch (let the arrow direct you) that corrects for the working pixel aspect ratio by squashing everything. See, the aliasing is gone. However our text (in this case) is squished. Now this isn’t a permanent effect, it just makes the aliasing go away while you’re working on the piece. But again the image is distorted, and I just don’t work that way.
[photopress:Picture_2_1_2_3_4_5_6_7_8_9_10_11_12_13_14_15_16_17_18.png,thumb,pp_image]
By beginning the project in square pixel you get the best of both worlds. The lines are not aliased in your working space and you don’t have to work with distorted images.
The second step to my workflow is to render out my video from After Effects. Typically I’ll render either a high quality H.264 or a lossless uncompressed clip. Then I run it through Final Cut Pro. Even if the clip is “as-is” from After Effects I pass it through this step so that every piece I prepare has seen the same workflow.
Upon export from Final Cut I force the square pixel video (864 pixels wide by 486 pixels tall) into a non-square pixel format, which is the preferred format for video systems.
I choose the File > Export As Quicktime option:
[photopress:save.png,thumb,pp_image]
Make sure to use the following settings:
[photopress:settings.png,thumb,pp_image]
Most importantly changing this option to force my square pixel composition into a non-square, video friendly format:
[photopress:pick.png,thumb,pp_image]
That’s it. Render, and done. If you want to read further, this wiki article explains it well.
Jesse J. Anderson
Interesting read – any recommendations on a good way to do that Final Cut render if you don’t own Final Cut? I do all my video editing within After Effects, but it seems silly to need a huge program like Final Cut just to do a simple quicktime conversion.
Also, why is it that your church only does SD resolution, and not 1280p HD or even 720p? Just curious.
David
Seems like QT Pro would do in a pinch.
A little experimentation uncovers iMovie & visualhub as workable as well.
But not as much success with Premiere.
ken
Jesse, you could set your “STRETCH” parameter in your After Effects render to the desired dimensions (720×486, 1.2 pixel aspect). Typically I do some more cleanup in final cut. I lay audio there, check levels, and nearly always create a 1 second fade to black and add a 1 second black slug to the end so every piece ends consistently.
David – true, QT would work. For us, aside from the fact that we do a little post cleanup in Final Cut, i’ve also found that our Grass Valley DDRs are very picky with file formats and respond better if they come from the same method.
ken
SD question? We have an SD signal right now (cameras and switcher) so building HD elements isn’t worth the extra render / build time. We don’t reuse much material either.
David Slone
Ken, have you tried tweaking compressor to use the same settings, i’ve found on my H264 projects that compressor actually yields a better quality and the file size is much smaller as well.
We are moving into our new building in 31 days and we are moving to an all HD workflow so I’ll let you know what I find
Brad Zimmerman
I would further your point with this:
If your church goes from computer to projector (via vga or dvi) you should create all our elements in square pixel format at the native resolution of the projector to get the best look. I call this Church Def, most projectors are at least 800 x 600 or 1024 x 768.
Ken, is newspring looking to go HD? Curious what your thoughts are on that, Companies like mankin and others make you think you have to be hd. The real question is what about stewardship in that upgrade, seems like a lot of money just for some extra pixels. Thoughts?
ken
Brad, at some point I believe we will go HD. But I agree with what you’ve stated, it’s a stewardship conversation. While I appreciate the extra clarity it really comes down to COST:BENEFIT analysis. Will I see more souls won for Christ because the videos are of a higher clarity? The answer would be partially philosophical. Are you in a media-centric culture that would diminish your message if it were not in HD?
For us the SD widescreen (vs. 4:3) was partially a product of that conversation. In our room the impact of SD widescreen makes our media feel more cinematic, more professional, and draws more attention to it. And functionally it equips us to more smoothly follow our pastor’s movements onstage without adding distraction. So yes, I can justify that with “makes the message clearer.” But for HD in our current context I don’t think I can make the same justification.
Jesse J. Anderson
Being that I don’t actually work in a church, I’m trying to find the best solutions for my http://newworshipmedia.com backgrounds – currently I offer them in SD and HD widescreen, but I wonder if I might switch to just SD 4:3 and SD 16:9.
Currently the 4:3 SD downloads far outweigh the 16:9 HD downloads and I wonder if the people that get the HD widescreen are really only downloading them for widescreen, with the extra pixels (and extra download size) being lost on them.
Jesse J. Anderson
Also, as far as pixel ratio, I’ve been rendering everything in square pixels… since I have no real background in video and limited understanding of how that works.
Is it correct to say that nearly all churches displaying in widescreen through a projector require that video to be at 1.2 pixels aspect ratio?
David Slone
Brad, if you were to go to Newspring and watch the screens you would think you were looking at an HD feed. That was my thought 2 years ago when I went to Unleash and was amazed to discover it was SD. The use of widescreen format and great SD cameras looks amazing.
ken
David, a big part of that is the fact that they are high grade SD cameras. For us a challenge in going to HD would be matching the same grade of camera in HD without going extravagantly (and prohibitively) expensive.