Analog or Digital Video: What's the difference?

The analog process encodes video and audio in complete frames (modulation), with the receiving device interpreting and translating the signal into video and audio on a monitor (de-modulation). This process can introduce a progressive loss of data leading to a general loss of video quality. NTSC can only deliver 720 pixels wide video or stills from video.

Digital video, or DV, on the other hand, remains digital (such as '0's and '1's ) with the data describing the colors and brightness of each video frame. On the receiving end of this data transmission, there is no translation or interpretation, just the delivery of pure data. The consistency of delivery is the crucial advantage that digital video has over analog video when it comes to working with images on a PC. As opposed to NTSC, there is no limit to resolution so images or movies as wide as 4000 pixels are easily obtainable with the digital cameras we sell for microscopy.

When introduced in 1995, Firewire, one of many electronic protocols for A/V also referred to as iLink, IEEE1394 or 1394, provided both the transfer speed, at 400Mpbs, and the consistency needed to allow the average user to edit video on their PC.

What About USB 2.0?

In the past, there was a clear distinction between USB and Firewire. USB 1.1 could not transfer high quality DV; loosely defined as 25 frames per second (fps) with each frame being 640x480 resolution, due to USB1.1's transfer limit of around 11Mbps (or around 1.5MB per second).

Transferring DV requires a transfer rate of at least 3.6MB per second, which at the time left Firewire as one of few options due to its ability to work at 400Mbps, or up to around 50MB per second. Then along came USB 2.0 with a "published" transfer rate of 480Mbps or 60MB per second. Not to be left behind by Wintel, at least on paper, Firewire800 or IEEE1394b was introduced. The new standard also provided for even faster 1.6Gbps and 3.2Gbps transfer rates across 100 meters of copper twisted pair wires.

At first glance, it appears that USB 2.0 is faster than Firewire400; however speed is not the only issue when it comes to DV. One of the worst issues with USB 2.0 is that it cannot guarantee a sustained data transfer rate. This is due to USB adopting a "master-slave" topology, which means it needs the computer's CPU to coordinate data transfers. While this not usually a problem for low demand peripherals such as webcams, scanners, printers, etc., digital video requires dependable high-performance to avoid dropping video frames.

Firewire was designed from the beginning as a real time protocol. Firewire also works in a peer-to-peer topology. As a result, many professional DV users can download their video clips from a DV camcorder directly to a hard drive without the use of a PC. More importantly, Firewire delivers data consistently at a specified high rate. If you want to do serious work with video, even to edit a family movie, it is best to go with Firewire.

What does Meiji recommend for microscopy?

Analog CCD cameras are still the best way to go if you want to use a video projector or a big screen TV or monitor like in classroom or training situations. To work with high-resolution digital video or digital still images for print publication, then our CMOS or CCD Digital Video Cameras are the best choice.

Digital video cameras that use USB2.0 are fine for work done with microscopes because videos captured on microscopes are relatively short clips in duration. Also when using a USB2.0 video system, we suggest using a newer, fast computer with no other applications or TSR's running in the background or better yet, using a dedicated computer to do microscope video imaging.

USB2.0 is found on all new PC or Macintosh type computers, whereas Firewire is typically an add-on card for most PC's. All Meiji Techno Digital Video Cameras use USB2.0 with no current plans for Firewire cameras. Firewire is native to most Macintosh computers so finding a Firewire camera is probably the best way to go if you are a Mac user.