AVID Cinema

Sometimes the most forgotten products are the ones that opened the doors for the things we take for granted. Today everyone is armed with a smartphone, and for most of us the smart phone is equipped with a video camera….most of which are HD (High Definition). It is something we don't really think too much about anymore. We take it out of our pocket, push record, and when done click an upload button, instantly sharing our videos with everyone. Well, it wasn't always that easy. It had to start somewhere and grow.

Let's go back to the early nineties. With the Quadra 840av, Apple began to ship computers capable of capturing video. Well, when I say capturing, I don't mean the fluid video of today. The first Quadra was capable of recording video at 320 x 240 at 24 fps. This is half the resolution of television, which is 640 x 480 at 29.97 fps. The Quadra's limited hard drive size and speed also made maintaining full resolution video a challenge. Initially the Quadra's development team was planning to imbed System 7, the Quadra's operating system, on a 4MB ROM chip which would have improved video performance and freed up the hard drive to make video recording and playback smoother. This however was scrapped at the last minute. The Quadra was basically designed for capturing still video images and producing CD-ROM videos. While the Quadra 840AV was targeted at the business market, it was the start of providing video editing and sharing to the masses. Apple would improve on this with the Power Macintosh 6100, 7100, & 8100av series of Macintoshes. These would see the same limitations as the Quadra. Full frame video was still not easily achieved. There were several products introduced that used expansion slots for hardware compression, but it required such a significant investment that it was out of reach of the average user.

Apple decided it wanted to get serious about video as they saw the potential for a whole new market. Now AVID is a company that specializes in video capture hardware and video editing software. Apple approached them in 1994/1995 about working together to build a home production Mac. This would be the Power Macintosh 6400. You may not realize this, but this is the most important Macintosh in video editing/sharing history.

The problem that Apple was facing was that the hardware in 1996 still had basically the same video limitations as the Quadras. There just isn't enough bandwidth between the processor, hard drives, and capture hardware. Technology was moving slow to catch up to the video revolution off in the distance. When they approached AVID, it was to find a way around this limitation and bring video to the masses. Apple needed two things. The first was hardware that could capture and output full resolution video while still making the Mac affordable. The other was to give the 6400 video editing software aimed at consumers. Capturing and editing video had to be easy, seamless, and without effort. A user simply needed to plug in a video camera, launch the software, and click record. And thats exactly what AVID delivered. It was called AVID Cinema.

AVID and Apple sat down and went over the parts already available to the system. Why re-invent the wheel? Apple was already producing a video capture solution, the Apple Video System. This device featured a composite video input, stereo audio input, and an s-video input. Let's talk about the video inputs for a minute. The S-video input already being in place made a significant difference. S-video differs from composite video in a very important way. Basically a composite input carries the luminance, color, and frame synchronization information together. The problem with composite is because of this combining, the limited bandwidth means less data and less control. You can't adjust any attribute of the signal without causing a reaction to another. For video capture there just isn't enough information or flexibility to get a high quality result. The lack of signal information leads the compression algorithms to add more noise and color saturation artifacts.

This brings us to S-video. S-video (or Y/C) addresses the color quality issues by separating out the Y or luminance and C or color signals. The ability to adjust these attributes separately allows for a higher quality recording with more information available for the computer to adjust the signal. Being able to adjust the brightness of the image without affecting the color signal means your images will have more definition and less color saturation noise and artifacts. Having an already developed and proven s-video and composite input meant that AVID didn't have to develop a video input system, only the hardware compression technology. Apple had been building these capture boards already with an expansion connector. This allowed Apple and third party developers to connect internal PCI or NuBus cards to directly siphon off the video being captured. This connector also allowed developers to bypass all the Apple compression and processing hardware--perfect for AVID.

AVID decided that it wouldn't be able to capture full 640 x 480 at 29.97 fps and be able to play it back in high quality on the 6400. It simply did not have the bandwidth in its architecture. With the goal of keeping this product within the budget AVID decided to compress the video on the fly with a special board. The format M-JPEG (motion JPEG) was chosen. Basically what motion does JPEG is make a progressive string of JPEG image files which are compressed individually. I would like to note that M-JPEG is the same compression used on todays digital cinema projection systems. By compressing on the fly with special hardware there was no need for the Macintosh to do any CPU processing, which meant the video could be written to the hard drive already compressed. Once captured, the video was ready to edit. This was huge. No conversion, rendering, or waiting. Just capture, edit, playback.

AVID and Apple agreed that the Power Macintosh could play back video in 320 x 240 all day long, without incident. So this was decided to be the native size of the captured video. Apple wanted this product to be usable on any Power Macintosh or Performa 6400 no matter what the specs were. The goal was to make it always work, all the time. So the solution from AVID was to use its custom hardware to increase the video size at playback using a process known as two-dimensional linear interpolation. Basically what this process does is use a fancy algorithm to increase the video frame size from 320 x 240 to 640 x 480 by adding pixels.

It uses the pixel data already present, stretches the image, then uses math to add pixels and fill the data gaps. In the left image you can see an example of this process.The disadvantage to this method is you will likely see aliasing, blurring, and edge halos in the final image. Apple has used this process before in the Apple Video System, but AVID knew how to do it better. By having the AVID card do the calculations

in real time, they were able to play back the captured video at 640 x 480 running at 29.97 fps. Being compressed with M-JPEG also gave them a high quality video file that was much smaller than most formats. While the quality was not as good as capturing at 640 x 480, it resulted in a very good image that can be recorded to video tape. Being stored at a third of the size also meant that it took up less disk space, which was another obstacle for video editing. Another advantage to this setup is: like professionals at the time, you could preview your video on a TV in real time.

This system would find its way into homes, schools, and businesses. Finally, Apple, with the help of AVID, made a product that would bring video to the masses. Schools especially took advantage of this hardware. For the price of just the Mac,

you could get a video editing solution. This was where desktop video editing and sharing was perfected. This was the product that laid a solid foundation for not only hardware, but for software. AVID Cinema's software component gave everyone from kids to grandparents the ability to create videos quickly and easily. Later on the iMac would get its own USB based AVID cinema product that would start the age of internet videos.

The AVID Cinema package and the Power Macintosh 6400 are probably the most important products of the video revolution that you have never heard of. Without them, the landscape might be very different today.

 

Sources:

http://apple.com (archive)

http://avidcinema.com (archive)

http://en.wikipedia.org/wiki/Bilinear_interpolation

http://www.storiesofapple.net/tempest-cyclone-the-first-audio-video-macs.html

http://www.68kmac.org/articles.php?id=37

https://discussions.apple.com/message/3385420#3385420

http://www.videomaker.com/article/7438-video-streaming-software-review-avid-cinema-for-macintosh

http://www.everymac.com/systems/apple/powermac/specs/powermac_6400_200.html

http://www.zone6400.com/files/avidcinema.html

 

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