7D's H.264 VS XDCAM EX

Madaspy

Madaspy

Active member
First and formost i know i am going to be making some general assumptions about formats and bit rates based on the lack of detailed and consistent information about the 7D.

At work we used the EX-3 and shoot primarily at 108030p in the XDCAM-EX codec which is approximately 35Mbps or 4.375MB/s. For instance a 3:07;12 clip is 811.1MB. Its data rate is aprox 4.33MB/s or 34.70Mbps. Also, XDCAM is a close variant of the HDV format with a color sub sampling of 4:2:0.

Here is where i am making assumptions based on a single video clip, but please bare with me.

DP review has a lengthy preview of the camera posted on its site.http://www.dpreview.com/previews/canoneos7d/page14.asp Contained within the preview is a clean unmodified, non-recompressed, straight out of the camera H.264 mov file. The file is 7.8 seconds (07;24) in duration, with a file size of 44.7MB. When calculated, the bitrate comes out to be 5.73MB/s or 45.85mbps.

Based on the bitrate between the two cameras, the 7D shoots at a higher bitrate, in theory, this equates to lower/less compression, and ultimately "higher image quality." I know that it is near impossible to compare codecs on the basis on bitrate alone.

Here is the real question/statement. Wouldn't the 7D be a nice fit for those who can't afford or justify the price of an ex1/ex3 or other HDV Cameras. Due to the 7D's lighter compression and substantially lower price. Even after noting that the 7D lacks professional audio input.

As a recent collage grad who shot a lot with the DVX100 and the V1U, the D7 would have been my dream camera due to the larger sensor, interchangeable lens, and relativity light compressed h.264 codec as compared to DV, HDV and XDCAM-EX.

What do you guys think?
 
If the only difference between the 5d's implementation of the codec and the 7d's is the bitrate (higher on the 7d) then you can fully expect the 7d to have "less compression" than the Ex-1/3. You have to remember that xdcam is based on mpeg2 and H.264 is mpeg4.

Mpeg4 is much more efficient than Mpeg2. Meaning, mpeg4 is less visual compression even at the same data rate as mpeg 2.

I have worked with both the 5d and Ex1/3 and can tell you without a doubt that Canon's H.264 codec holds up better than Xdcam, especially with heavy motion.

In all honesty I would rather own a 7d with a Zoom H4N than an Ex-3 (barring the discovery of major problems that aren't in the 7d specs).

My 5d is working a lot more than every Ex1/3 that I know.
 
Update, I have taken the file on DP review and thrown it in to Color. I do a lot of color correction at work, and the file "seemed" to hold up "better" than the XDCAM footage when using curves. It felt as if it took a more extreme change to the curve to introduce banding.
 
The short answer……yes.

The long answer…

I think it depends on what type of shooting you do, and what you want to do in the future. Personally, I own both the EX1 and GH1 (and pre-ordered a 7D this morning). Each project I shoot runs into the hundreds of gigabytes of footage, and sometimes into the terabytes. The idea of shooting and syncing audio for that much footage shot on any DSLR is a non-starter. It wouldn't matter if the image of the 7D was dipped in angel's blood and cured cancer, it just won't work as the main acquisition camera for my work.

Price is also a bit misleading. Sure, you can get the 7D (as I have ordered) with the kit lens for $1899. But chances are you'll find yourself adding other lenses, support equipment and other gear with the ultimate goal of making the 7D work more like a full-sized camera. And if you're anything like me (or many others on this board), you'll end up with a camera that delivers great images, but comes with a somewhat convoluted (double-system) workflow and lots of moving parts. This works for some, but not so well for others.

My work involves quickly being able to pull the camera out and start shooting. If I had to wrangle a Zoom H4N, a stabilizer/mount system and more, I'd likely miss the action in front of my, and I would have some unhappy clients. DSLRs make working this way a bit more challenging, though still possible, with some sacrifices.

Now, if your work is primarily narrative shooting, and your footage load is lower, then you have the option of relying on the 7D as your primary acquisition tool. You'll have the luxury of a more controlled set/location, more support gear and crew/talent to help manage it all.

In theory, your assumptions regarding bit-rates seem sound, even understanding the near-impossibility of comparing them. But full-sized cameras like the EX1 offer the versatility of HD/SDI-out, which opens a world of possibilities for bitrate. With the EX1 and my Nano Flash unit, I can shoot at 100Mbps (or up to 220Mbps) in XDCAM 422, which would, by every measure, exceed the codec performance of the 7D. The trade-off of course is file size, and managing that is an ongoing battle at bitrates that high.

But I also believe that, as many have said, we have long past the point of the camera being any kind of limiting factor in expressing your creativity. Think about the projects you shoot (and want to shoot). Identify the three/four cameras that give you the best ability to deliver those projects. Establish what your budget is. Buy the camera that fits.

No one will ever watch something captivating that was shot on an EX1 and say, "boy, I wish they'd have shot that on a 7D," and the opposite is also true.
 
As far as comparing codecs -- you can't compare them just on the numbers alone. In general, H.264 is two to 2.5 times as efficient as MPEG-2, meaning that to match XDCAM-EX's 35mbps, you'd only need about 17mbps of H.264.

However, that's in general -- and what you should be asking is "in specific", as in, does the 7D's specific implementation of h.264 match up? Because the XDCAM EX's 35mbps is easily the best MPEG-2 I've seen at that bitrate; it's an excellent implementation. It's not bulletproof, and in 60i it can be pushed too far, but the 24p is implemented well. So it remains to be seen how the 7D's implementation is handled; if they implement a full robust version including a reasonable GoP size and full IBP group structure, then it might be substantially superior to the XDCAM EX codec. Or, if they shortchanged it, then it might not be competitive with the XDCAM EX codec. It's all down to the particular implementation.
 
I agree with you Stephen. Having Hd-SDI is a great advantage.

Barry - what are your opinions of the 5d's codec compared to xdcam ex? I have found that the 5d's holds up much better under heavy detail and motion than xdcam ex.
 
Stephen, give us a break. If the quality of the images are high enough, the content won't even matter.

Sarcasm aside, none of the DSLR video products currently available (including 7D) are useful for any long form event capture such as a wedding or any all day event as the capture duration is just too short.

Professional content production houses are using them to produce commercials and some narrative work exploiting the DOF aspects, but that's a controlled short form shoot.

It's all much adio about nothing IMO. How clean do you need HD video to be? A small low cost video camera to use as a b-camera would be something to get excited about.
 
jeff9329 said:
Sarcasm aside, none of the DSLR video products currently available (including 7D) are useful for any long form event capture such as a wedding or any all day event as the capture duration is just too short.
Click to expand...
The GH1 is the exception; it has no capture duration, it can record for as long as your card has space.
 
jeff9329 said:
Sarcasm aside, none of the DSLR video products currently available (including 7D) are useful for any long form event capture such as a wedding or any all day event as the capture duration is just too short.
Click to expand...
Not true: the GH1 has no time limit, except that naturally imposed by the size of memory card. Though, technically the GH1 is not a "DSLR," so technically you're right.
 
It is amazing to me that this $1900 camera could and will most likely have better video than an EX1. Crazy stuff. It is a poor mans EX1 or is it a smart mans EX1?

Can't wait to get my hands on it!
 
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