What does clean HDMI really mean for the 5Dmkiii?

5Dmkiii Clean HDMI Out

If you’re like me you and your reading my site, chances are you’re into cameras and read other camera blogs. So you’ve probably seen everyone blogging about this Canon 5Dmkiii and it’s clean HDMI out firmware.

But what does that really mean? Why is everyone so excited about it and why now? 

A lot of times these camera manufactures release their dslrs with all these cool capabilities and slowly upgrade the software over time. This is one of those times. You see it happening with Blackmagic. They released their Cinema Camera and it was barely usable, from a user interface perspective. And we saw it with the Canon 5Dmkii when it released 24p. 


What Clean HDMI out does for Cinematographers and Videographers

Clean HDMI does a few things. One it allows cinematographers or camera nuts to record video onto external devices without having timecode or live view information burned into the image. Kind of a no brainer right? This was the problem before now it’s gone. This means when you’re recording video, you don’t have to record to Canon’s build in video codecs and you can now record to your own. (with an External HDMI recorder)This will help make post production quicker because you can record into a video codec that you can immediately start editing with. Like ProresHQ or DNxHD. 

This also means you can run your HDMI out cable to a preview monitor so the director can actually see what’s going on without burn-in data covering half the screen. 

The other really cool thing about Clean HDMI out is the quality of the signal. When capturing to a CF card you’re usually capturing in some form of an AVC MPEG-4 or H264 codec which are all heavily compressed giving you a chroma subsampling of something like a 4:2:0. Clean HDMI fixes this. Let me go into a little about the specs of the 5Dmkiii so there is a bit clearer of an understanding. 


Canon 5Dmkiii Video and Codec Specs

Currently the Canon 5Dmkiii shoots an AVC (Advanced Video Codec) H.264/MPEG-4 but with the option to shoot ALL-I Intraframe or IPB Interframe.


What is IPB Interframe?

IPB Interframe means you have keyframes in the compression. Say you have every 24th frame being a keyframe or I frame, then all the following frames are going to mathematically compare each pixel to the pixels of the previous frames up to the keyframe and render the image based on the difference in pixel information. So it looks at the pixels and says, did this pixel change, and by how much. A lot of times the pixels don’t change so it doen’t have to write ne data. Which is why this is a lighter codec.

You’ll see this a lot on old web video’s where when you skip ahead the video is all jibber jabber for a second or two until it hits the keyframe, then suddenly everything is clear. The porn industry used this compression a lot. And I’m sure you hated it. 

The benefit of this is a much smaller file size but not as accurate of color information when there are dramatic shifts in color and light between scenes. It also makes editing a bitch. 


What is ALL-I Intraframe?

ALL-I Intraframe is when every frame of video stands on its own. It does not require data from any other frame to create its compression. This is one of the main advantages of the Canon 5Dmkiii vs the 5Dmkii and it’s great. 


What is the AVC H.264/MPEG4 Codec in the Canon 5Dmkiii?

The H.264 Codec is an MPEG 4 codec. What’s the difference between H.264 and MPEG-4? They are the same kind of compression but H.264 is way better and about 2x as effecient. It allows for a higher compression rate allowing you to record more information with the same space. 

The Canon 5Dmkiii shoots H.264 but at 8-bit with a chroma subsample of 4:2:0. I’m not going to get into chroma subsampling because it will never make any sense. But just know there are three variants that are very popular right now. 4:2:0 which is found in H.264 and MPEG4. So a lot of web videos. Then there is 4:2:2 which is a great editing codec that preserves a ton of information. Like Prores(HQ) is a 10 -bit 4:2:2. Or Avid’s DNxHD. Then there is 4:4:4 this is an uncompressed chroma subsampling. Well it’s not completely uncompressed but all the color information isn’t a blended versions or estimated color like you get with 4:2:0. And it’s 16-bit. 

(By the way, if you’re a PC guy, download the Avid Codecs and always work in DNxHD. I get so many weird codecs from our PC using clients at work. it’s unbelievable. And stop using Animation. It’s not the 90’s anymore. :p )

If you’re a total video geek and have to know more about chroma sampling here you go: http://www.dvxuser.com/articles/colorspace/


The new Canon 5Dmkiii Clean HDMI

The new clean HDMI on the Canon now outputs a clean 4:2:2 10-bit signal. This means you can record on an external recorder straight into Prores(HQ) or DNxHD without any loss of information and you’ll have a great 10-bit color sampling. This is a big deal. Prores(HQ) 4:2:2 is the industry standard, both for delivering finals to clients and for editing. Clients always ask for it. And if a client’s not asking for it we make them take it. It’s great. I always work in Prores(HQ). It’s fast, efficient, creates great file sizes and is even good for greenscreens and effects.

Hopefully our next gen cameras or maybe even another firmware upgrade will just give us 4:4:4. That would be something.

So there it is, you should now have a clear understanding of clean HDMI out on the Canon 5Dmkiii. And now you can see why everyone is so excited. It was a feature that should have been in launch but wasn’t. I guess Canon had bigger priorities at the time.

Oh and while we’re on the subject. Don’t ever buy those $90 dollar gold coated HDMI cables from Bestbuy. You can get them on Amazon for $5-10 bucks. 


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