Canon

Is the 1Dx mkII MJEPG bad codec?

Long GOP

Since the Canon 1Dc was launched with its high bitrate (520Mbps) MJPEG 422 8bit codec, self proclaimed experts have been complaining that it’s old technology, inefficient and Canon really should have used XAVC.

Is it really as bad as they say, or is there more to the story?

The main complaints are:

  • inefficient compression (large files)
  • poor playback performance (old, not optimized video compression).

The short story

The short story is that it’s a good way to store high quality video files, it was the best available to Canon at the time (in a DSLR), but yes, a dedicated video encoding chip that offered intra frame XAVC would have been even better. Canon’s relatively cheap XC-10 UHD camera uses the new XAVC codec for example (305Mbps). The XC-10 camera has a Digic DV5 chip that makes it possible.

UPDATE: If the 1Dx mkII had access to a DV5 chip like the XC-10 and the C300 mkII, its file sizes would land between 325 Mbps (XC-10 bitrate at 4096x2160) or 410 Mbps (what the C300 mkII uses). These are good examples of modern intra frame compression. The benefit would be better compression and no need to convert files for editing.

The long story

Now, the long story is, as expected, much more nuanced. Let’s look at the two main complaints.

Inefficient compression. When you record 4k files at 500Mbps, the gigabytes of your memory cards get eaten up like you wouldn’t believe. Every 15 seconds you save a GB worth of data. So that’s bad, right?

Well… compared to what?

Had you saved your compressed video directly to ProRes 422, a codec often hailed as a golden standard and a good compromise between file size, quality and great playback performance—your files would have been even bigger. OK, so the compression is better than ProRes then? Well, from a storage point of view—yes. It shouldn’t be that surprising that the compression is good. MJEPG stands for Motion JPEG and we have all used .jpg to compress our photos and images for many, many years. And of course, jpeg is not only a consumer compression format. It’s used every day in all kinds of professional applications because the quality is great.

I feel that the mistake most people do first is to compare the Canon 1Dx mkII, or Canon 1Dc’s codec, which is an intra frame codec, to modern consumer camera codecs that are inter frame (long GOP).

Intra frame means that you store each frame of video as a unique image frame and then you compress that. Just like you would compress a raw photo to a jpeg photo. This is what the Canon 1Dx mkII and Canon 1Dc do. They basically save 25 jpeg photos per second in 4096x2160 px resolution.

Consumer cameras achieve great compression by only saving a small number of actual frames out of the 25 images per second. Out of 25 ‘frames’ you might get 3 actual images. All of the other frames get only partially saved and then calculated (estimated) by advanced mathematical calculations. It certainly saves space, but it also famously introduces various image artifacts. Typically Long GOP codecs have problems when the image content change a lot from frame to frame. Examples of this might be flowing water, foliage that is blowing in the wind or simply that the camera moves. Most of the time, a non critical user won’t see these imperfections. And final delivery of even the highest end cameras mostly end up in this format for display (but they don’t get captured that way). But while it’s a great delivery format, I don’t want to capture my images this way.

Lesson: Don’t compare data rates between intra frame to inter frame. They are not the same thing!!

Poor playback performance. This I have no problem agreeing with—because it’s more objectively true. MJPEG has very low requirements at time of compression. That’s great because it means cameras can use it even if they don’t have super fast CPU. It also requires less power and saves your battery. But it isn’t optimized for playback in editing software and your playback will likely stutter. Not good.

Well, I (almost) wouldn’t know, because my files get converted to ProRes on import into FCPX. I then replace the original files and have ProRes 422 masters. They are a little bit larger, but it’s negligible. Playback performance is a total non issue to me and the same should apply to anyone—just convert the files once.



Note: The reason the Canon 1Dc and now the 1Dx mkII uses the older MJPEG compression is because they are DSLRs that use Digic chips and not Digic Video (DV) found in Canon’s video cameras. For a Canon DSLR to use a dedicated video codec, Canon would need to integrate a DV chip, or perhaps launch new hybrid Digic chips that have these types of codecs built in. Legacy h.264 compression is already integrated in the DSLR Digic chip, which is the reason all Canon DSLRs use that for their video recording (8bit, 420, h.264 at modest bitrates).

Canon 1Dx mkII as 1Dc replacement?

The king is dead, long live the king

Canon has announced their new pro body, the Canon 1Dx mkII. Apart from expected general improvements to its predecessor—the Canon 1Dx—it also improves on some features found in the more expensive cinema eos version of the same body—the Canon Cinema EOS 1Dc.
The Canon 1Dc was launched at a price of around $12.000 when the 1Dx cost about $6800. It was a hefty difference for a very similar feature set. The main distinguishing features of the 1Dc was the internal 4k video recording capability at high bit rates of 520 Mbit/s as well as having Canon’s cinema picture profile, Canon Log.

Canon’s new camera, the 1Dx mkII, improves the internal 4k recording capability and can record 60 fps at 800Mbit/s. Since it isn’t a part of the Cinema EOS family, it doesn’t get Canon Log at launch. While the absence of Canon Log is a frustration to existing 1Dc users and new hopefuls, the new 1Dx mkII offers Canon’s excellent Dual Pixel auto focusing system—a first for a full frame sensor.

It begs the question: does the improved frame rates and added DPAF functionality outweigh the lack of Canon Log? The Log picture profile is a large contributor to the final look of the image and sets the 1Dc apart from cheaper more accessible DSLRs.

Can the new 1Dx mkII replace my 1Dc?

I have been a Canon 1Dc user since April 2013. I was one of the very first owners in Switzerland. I like the camera very much and shoot my videos exclusively in Canon Log. Since I already have access to the normal picture profiles on my 1Dc—as well as Canon Log—I have started investigating how much it will hurt me if I have to fall back to, let’s say the ‘Normal’ picture profile with all the settings like contrast and sharpness turned down.

In a series of blog posts I will go through my own mental check list to see where I land. I have already ordered a 1Dx mkII, but delivery is not until April or so. The reason being, I already know that the usability features of the 1Dx mkII like DPAF, 4k60p and some GPS functionality will make it my go to camera for personal stuff. I will keep my 1Dc initially and in comparing the two cameras I will call out the differences as I see them. I don’t feel biased one way or another.

It will be fun and educational!