News from HQ by Philip Harding
Written by Jaime Walden of the John Lennon Bus
Today is a wonderful day. Thanks to the Digital Media Academy, I will now be traveling in style with my new MacBook Air. Or, as Brian calls it, “Our first MBA!” MACGyver and myself will be taking our first trip together to Palm Springs, CA for CUE 2009 March 5-7. Over the course of our days there, we’ll be conducting a high school recording session and video premiere, giving tours, and holding “Ask the Expert” video production, web design, iLife, and special effects demos with the Digital Media Academy at our booth. Stop by and say hello, MACGyver and I will be the two smallest ones there.
On Mama’s Jukebox: Elliott Smith – “Ballad of Big Nothing”
News from HQ by Philip Harding
Written by Jeff Sobel of the John Lennon Bus
A video producer often needs to be able to estimate the size of a video file before that video has been recorded, imported or exported. Do you need a magic crystal ball to predict how large a video file will be before you hit that Export button? Nope. You just need a 5th grader’s grasp of basic math. Here’s how:
Let’s take the example of exporting a video using Apple’s Compressor which comes standard with Final Cut Studio 2.
The first thing you should know is that digital video is encoded at a certain datarate, commonly called the bitrate. Higher bitrates generally produce better quality video (less “pixelation” or graininess) but will create larger files. You need to be sure that you choose a bitrate that’s high enough to achieve satisfactory quality but not so high that the video can’t be streamed on the web, downloaded in a reasonable amount of time, emailed, or however you intend to get it to your audience. Compressor has presets which are great starting points for making this decision.
You’ll see that there are two different presets for iPod/iPhone. The 1st is “h.264 video @ 600kbps” and the 2nd is “h.264 video @ 1500kbps”. Now, it’s safe to assume that the 2nd preset will produce better quality video, but how big will the files be? Let say we have a 2min long video and we’re hoping to compress it to a small enough filesize to be able to email it. Will the 600kbps setting do that for us? Let’s figure it out.
The 1st thing you need to know is that “600kbps” stands for “600 kilobits per second”. Now, we’re all pretty used to hearing about kilobytes, megabytes, even terabytes. But what’s a kilobit? A bit is the smallest piece of data there is. We represent bit with a lowercase b and byte with an uppercase B. All you need to know is:
There are 8 bits in a byte.
There are 1024 bits in a kilobit.
There are 1024 kilobits in a kilobyte.
There are 1024 kilobytes in a megabyte.
It’s not nearly as complicated as it might seem at first. It’s just like measurements you make in a kitchen. You know, 16oz in a pint, 2 pints in a quart, 4 quarts in a gallon, etc…
So let’s figure out how big our 2min video is going to be after we compress it using the 600kbps preset in Compressor:
600kbps / 8 = 75 kilobytes per second
75KB/s * 60 = 4500 kilobytes per minute
4500KB/m / 1024 = 4.4 megabytes per minute
Our 2min video is going to be about 9megabytes when exported with this preset. Small enough that you might be able to email it.
Now what if we compressed it using the AppleTV preset? That’s a 5mbps bitrate (5 megabits per second) so:
5mbps * 1024 = 5120 kilobits per second
5120kbps / 8 = 640 kilobytes per second
640KB/s * 60 = 38,400KB per minute
38,400KB / 1024 = 37.5 megabytes per minute
At this setting our 2min video will be about 75 megabytes. Much larger. But it’s going to look much better as well, even on an HD TV.
In our next installment we’ll talk about how you can estimate how much disk space you’ll need before capturing or importing your footage from a video camera.
If you know anything about the John Lennon bus you’ll know that we travel the country 10 months out of the year making music and video projects with students around the country. We’ve recently teamed up with the Digital Media Academy to bring week long, hands on music video production courses to campuses across the nation this summer. The course is called “Come Together” and will offer in depth instruction on the creation of music videos all the way from droppin’ beats like a clumsy farmer to editing like Spielberg, that’s Mr. Spielberg to you buddy.
I’ll be co-instructing the Music Video course with an experienced member of the DMA team, Travis Schlaffman, who has led teen summer camps from DMA now for six years and has a lot to teach and some pretty cool tattoos!! I’m looking forward to it and It should be a great collision of Bus style projects fused with DMA’s critical hands on learning. For more info visit:digitalmediaacademy.org. See you this summer!