One of the hardest thing to teach is video compression, because it’s really difficult to visualize what’s going on at a low level. One of the best tools for understanding what’s going on inside a highly compressed video file is Textronix’ MTS4EA software. It gives you a full visual analysis with motion vectors and macroblock coefficients and everything else a math geek could want. Unfortunately, even with the generous educational discount, it’s still a bit out of most students’ price range. About $20,000 out of their price range. Bummer.

However … I’ve just become aware of a little application from Apple called MovieVideoChart. This program (described in depth in WWDC05 Session 208 for you ADC members) gives you a visual representation of each frame of your compressed video, showing you which frames are keyframes, which are intermediate, and how they’re reordered in your video.

Picture 2

In the above screenshot, you can see a few things. The red frame (marked with the word “sync”) is an I-Frame. It’s the start of a GOP. In this case, this video has 150 frames between each keyframe, which is pretty extreme, but generally OK with modern codecs. Frames tagged “droppable” are are B frames (B frames can generally be ignored without breaking other frames, so they’re the first to get dropped on a slow system). Everything else is a P frame.

The bottom row is showing you the order in which the frames are decoded. The middle row shows you order in which the frames are displayed. The top row would should you the effects of any edits made to the file itself.

This can teach you a lot about modern (h.264 in this case) video compression. Frame reordering is an important concept. If you want to understand why B frames are so important, just look at the “data size” entry for the B (droppable) frames. Most frames are running between 2000 and 4000 bytes (P and I frames respectively) but the B frame is between 130 and 700 bytes! That’s a pretty huge reduction, and that’s just one of the many things you can learn from this free program.

A full explanation of I P and B frames is out of the scope of this post (though I’d be happy to geek about it someday), but Apple has an OK blurb up if you’re curious. Otherwise, take a look at MovieVideoChart. You might also be interested in Dumpster (at the bottom of the page) which shows you some good information about the internal constructs of your video file.

Production Assistant’s Handbook

(leeching from HDForIndies)

There’s a free PDF book called the Production Assistant’s Handbook, available for download from NoEnd Press.

I haven’t read through the whole thing, but I think there are some good tips in there. I think this might be a useful document for folks who are looking at moving from the sheltered world of the University into the scary, cold, Real World™.

The folding instructions are far too complicated for me though. Fold in half? Hu? I just keep ending up with a swan…

Got my Firestore Update

We received our Firestore FS4ProHD 2.0 firmware update disc today. Installation was straightforward, and it seems to work as promised. I captured 1080i60 HDV off the Canon XL-H1 with no trouble, and it happily opened in Quicktime. I’ll post more once I’ve had a chance to play with some of the other new features. For now, it’s all a boy could want (save for 24f support …).

Artemis Camera Stabilizer has a nice review of the Artemis DV Pro camera stabilizer (not a SteadiCam™). I’m not familiar with this setup, but it looks very interesting. In particular, I like the integrated monitor and power cabling. The high quality screen is another major plus. It looks like it’s good for cameras up to around 20lbs, which is pretty reasonable. Not as affordable as some of the lesser Glidecam systems, but still pretty snazzy.

Doing the XDCamHD Math

I’m still interested in the XDCamHD product line, and have been doing a bit of investigation regarding lens choices. Both Canon and Fujinon have a few lenses available to work with the 1/2″ chips used by the XDCam.

Half-inch is a bit of an odd size for a CCD sensor, so I didn’t have a good sense of how to compare focal lengths on the lenses. Most of them have a wide angle of 5.5mm-6.7mm, and I wanted to know if that would be “wide enough.”

Read on to follow my exciting adventure!

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Oh man. Puns.

DVGuru has a great little post about some freebie fonts for movie credits, as well as box templates for DVD cases. They’re a bit tricky to download on the Mac though – control click the links, do “save linked file to desktop,” then rename the file to be just .rar, instead of .rar.txt. Then you can double click it and all is well. See, I added value to the post, instead of just shamelessly copying DVGuru. +1 for me.