Digital Video Camcorders

As recently as the first half of the 1990s few would have dreamed that before long camcorders would be viewed as a PC peripheral and that video editing would have become one of the fastest growing PC applications. All that changed with the introduction of Sony’s DV format in 1995 and the subsequent almost universal adoption of the IEEE 1394 interface, making a digital camcorder almost as easy to attach to a PC system as a mouse. Suddenly enthusiasts had access to a technology that allowed them to produce source material in a digital format whose quality far exceeded that of the analogue consumer formats available at the time – such as Hi-8 and S-VHS – and to turn this into professional-looking home movies at their desktop PC!

Recording and storing video (and audio) as a digital code eliminates the potential for a whole range of picture (and sound) artefacts and errors – in much the same way as the music CD improved on vinyl LP records. DV cassettes won’t play in VCRs, of course, but any digital camcorder will include conventional, analogue AV output jacks to allow recorded material to be transferred to VCR or viewed on a TV set. As alluded to previously, IEEE 1394 has become ubiquitous in the field of consumer video and this is the technology used to transfer footage from one digital camera to another, to a digital VCR or to a PC. In a development that is a great boon to long-time video enthusiasts, digital camcorders are increasingly equipped with analogue audio and video inputs, allowing the copying of older VHS or 8mm analogue recordings to DV format, and thereby providing both lossless archiving as well as access to DV’s powerful editing potential.

In fact, historically most camcorders sold in Europe had their DV-in connection deactivated, making it impossible to use the camcorder to transfer footage that had been edited on a PC back to tape. The rationale lies with European legislation which views a device capable of recording material input not only through its own lens, but also from an external source, to be more of a video recorder than a video camera when it comes to import taxes. The consequence was that manufacturers chose to disabled their camcorders’ ability to record from external sources simply so as to keep prices competitive and comparable to those in Japan and the USA. Since it was not illegal for an owner of one of these camcorders to subsequently reactivate its DV-in themselves, the situation inevitably gave rise to a mini-industry of DV-in-enabling solutions. The attitude of the camcorder manufacturers was ambiguous. On the one hand they couldn’t actively promote reactivation, since to do so would expose them to the risk of being liable for unpaid customs duties. On the other hand camcorders that were simply unable to have their DV-in reactivated sold far less well than those that could! Thankfully by early 2002 things had changed somewhat – possibly as a consequence of prices having fallen so much in recent years – and an increasing number of digital camcorders were being sold in Europe with their DV-in enabled.

A digital camcorder’s CCD – typically 1/4in in size – collects and processes light coming in from the lens and converts it into an electric signal. While average consumer camcorders are equipped with a single CCD, higher-end models feature three. In this case, a prism inside the lens barrel splits incoming light into its three primary colours, with each being fed to a different chip. The result – albeit at a significant additional cost – is excellent colour reproduction and image quality, noticeably better than single-CCD models are capable of.

The number of pixels that make up a CCD can vary greatly from one model to another and, as far as video is concerned at least, more pixels don’t necessarily mean better image quality. CCDs in Canon’s digital camcorders, for example, typically have a much lower pixel count than in models from JVC or Panasonic, but are still capable of achieving excellent results.

Digital camcorders support all the standard controls such as zoom, focus, white balance, and backlighting, as well as a number of other features – such as still image capabilities, infrared recording for night shots, editing controls and all manner of digital effects – many of which were simply inconceivable in the analogue domain.

Modern-day units deliver powerful telephoto-to-macro abilities through both a conventional, optical zoom – typically 10x or more – and digital zoom technology that employs video digital signal processing (DSP) to extend zoom ranges to as much as 200x. Of course, at these extremes images tend to become highly pixelated and image stability becomes a more significant problem. Generally, there’ll be two viewfinder options: a traditional eyepiece and a flip-out, adjustable colour LCD viewscreen. This may even be touch-sensitive, allowing an object to be digitally zoomed by touching it on the screen!

Many mainstream consumer digital camcorders are sold as all-in-one solutions for video, stills and even MP3 and email. Most can only capture stills at a resolution similar to that of DV video – 720×576 pixels – a resolution that is usually reduced to 640×480 in order to retain the correct aspect ratio. Some camcorders boast higher resolutions for stills, but often these larger images have been interpolated to reach the specified resolution. As a guide, a 1.5 megapixel camcorder will allow non-interpolated stills of 1360×1020. The ability to record still images is also an increasingly popular feature on professional digital camcorders, with some even capable of switching their image sensors over to a computer-friendly progressive-scan picture-assembling format that’s optimised for still-image capture.

Most digital camcorders feature either digital or optical image-stabilisation to reduce the jitter that inevitably accompanies hand-held shooting. Digital Image Stabilisation (DIS) is highly effective but tends to decrease picture resolution since when it’s engaged a smaller percentage of the image sensor is actively used for recording (the rest is employed in the stabilisation processing). Optical Image Stabilisation (OIS) employs a prism that variably adjusts the path of the light as it travels through the camera’s lens system. Both methods achieve the roughly same visible stability, but OIS is arguably better since it doesn’t reduce resolution.

One of the most recent digital camcorder features is Internet connectivity. Camcorders equipped with a Bluetooth interface can connect to the Internet either via a mobile telephone handset or land-line exchange connection, thereby allowing access to email and the WWW.

As of the early 2000s, the primary digital camcorder formats were:

  • Mini-DV: The most common format, mini-DV tape is 6.35mm wide, about 1/12th the size of VHS tape and provides a recording capability of up to 90 minutes in long-play mode at 500 lines of resolution. Camcorders using the format are often small enough to comfortably fit in the palm of one’s hand.
  • Digital8: Introduced in early 1999, Sony’s Digital8 camcorders can be viewed as a step between 8mm or Hi-8 and MiniDV. They record at almost the same quality as MiniDV, but to 8mm and Hi-8 tapes, which are about 1/4th the size of a VHS tape and offer a capacity of up to an hour. The format is a good choice for those upgrading to a digital camcorder, since Digital8 camcorders can also playback older 8mm and Hi-8 analogue videos.
  • MICROMV: In 2001 Sony announced its MICROMV range of digital camcorders that use MPEG-2 compression to record DV-quality signals to tapes that are 70% of the size of miniDV cassettes. At 12 Mbit/s, the ultra-compact MICROMV format has a bit rate of less than half that of miniDV, making video editing on a PC a far less resource-hungry task.
  • DVD: in a move that illustrated the continuing migration of AV applications to the PC domain, Hitachi announced the first digital camcorder capable of recording to DVD media – in this case the DVD-RAM variety – in the summer of 2000. An important advantage of the DVD format is the ability to index a video and to jump directly to specific scenes of a recorded video, thereby saving both recording/editing time and battery power.