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QuickTime Animation vs. H.264 for screencasts
Hi everyone,
I’m contemplating whether to use H.264 or QuickTime Animation for my screencast recordings. I’ve switched to ProRes since the introduction of FCPX, but the files are really really large. A QT Animation is a fraction of the size of a ProRes file and it’s, after all the years, still among the supported formats. So I’m wondering how likely it is to go away. I thought it was based on Carbon. Did Apple re-implement it to AV Foundation? Does it use 64-bit or is it still a 32-bit codec?
If that doesn’t work, I probably switch to H.264. The encodings are even smaller than Animation, but the downside is that I have a discoloration problem. Anyone’s got an idea where this is coming from? You can see it in the title bar of the window, around the corner of the green dot. When looking at the full screen frame the entire title bar is less white compared to the original ProRes encoding.
Thank you!
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5 Replies
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I record all of my screencasts using Camtasia for Mac which contains the excellent TechSmith TSCC/TSC2 codecs designed specifically for screen capture but I would imagine that the Animation codec would be the next best for screen capture because, as it’s name implies. it is designed to handle computer generated graphics extremely well which is what a screen capture is. I deliver all of my screencasts as AVC/H.264 MP4 but I don’t record with that.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
Thank you for the mention of TSC. I didn’t know TechSmith had a special codec for this.
One question remains: where does the discoloration come from and how to fix it?
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[Andreas Zeitler] “One question remains: where does the discoloration come from and how to fix it?”
I believe what you are referring to are compression artifacts from the MPEG4 codec. MPEG-4 H.264/AVC is a block-oriented “motion-compensation” based codec. As such it encodes blocks of pixels that are similar as the same color pattern to save space. In nature, there are very few purely solid colors or sharp lines so these blocks go mostly unnoticed. With computer generated graphics these block boundary artifacts show themselves. This is why titles over video sometimes don’t have clean edges. The only way to avoid this is to not use a block-oriented codec like MPEG. The QuickTime Animation codec and codecs like TechSmoth TSCC don’t use block encoding so they don’t exhibit these artifacts.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
“I believe what you are referring to are compression artifacts from the MPEG4 codec.”
I don’t. If you read my original message and look at the picture that I’ve posted, the discoloration goes beyond a normal “artifact”. It doesn’t matter how high I set the keyframe rate, and it doesn’t matter how high I set the encoding bitrate, the titlebar and the green knob is always in a different color. As far as I’m aware, this shouldn’t happen.
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[Andreas Zeitler] “the titlebar and the green knob is always in a different color.”
Well… I measured them with the Mac Digital Color Meter and the green bars are really close to the same color. The ProRes green title bar to the right of the word MindNode is a solid R:24 G:64 B:58 while the same area on the left alternates around R:26 G:60 B:53. The variable colors on the MPEG4 side are from the block compression. Even still, those RGB values are not too far from each other.
You have to take into account that MPEG4 is a lossy codec. That means you will NOT get out of it what you put into it, guaranteed!. Information will be lost. Thats how it achieves it’s high compression rates. If you want to be that critical about color then you need to use a lossless codec.
~jr
http://www.johnrofrano.com
http://www.vasst.com
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