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Digital Video From Capture to Web
Tom Arah makes the shift from photo-editing to DV-based video editing.
The field of design is always changing. Over time print design has grown to accommodate Web design and vector illustration has grown to include 2D and even 3D animation. Just as significant is the move in the bitmap world away from still photographs to dynamic video. These days you're as likely to be asked to produce a DVD for the launch of a new product as a brochure, or to publish the managing director's actual speech on the company web site as to report it in a newsletter.
You might think that this change from static image to moving video would be relatively straightforward. After all both are based on the same basic unit: the pixel. The shift is quantitative rather than qualitative - but it's some shift. A single frame of a typical video produces over 1MB of uncompressed data. With between 25 and 30 frames a second that scales up to a typical video throughput of around 30 MB/sec which eats up over 1.5 gigabytes per minute!
Clearly these transfer rates and storage requirements simply aren't feasible. The only way to give your system a chance of coping is with some hardware dedicated to COmpressing and DECompressing the video stream based on an algorithmic "CODEC". From the world of still images the JPEG format is recognized as the best option for high levels of compression with minimal loss of visual quality (see RW 67) and the Motion JPEG (MJPEG) codec simply applies JPEG compression to individual frames in succession. Even higher compression is possible with the MPEG-1 and MPEG-2 (Moving Picture Experts Group) formats which add in interframe compression to ensure that only those areas of the video which change from one frame to the next are encoded.
Publishing video to DVD and the Web is now within easy reach.
Codecs make video editing on the computer viable but they have serious downsides. To begin with they demand expensive hardware to enable the analog video to be captured in real time, with cheaper options often requiring a drop in frame size or rate to avoid the nightmare of lost frames. Once captured, the video is also often tied to the capturing machine as it needs the hardware for real time decompression (the alternative is to use open asymmetric codecs where less processing is needed for playback). Codecs are also intrinsically "lossy" and involve a drop in quality each time the video is transcoded. Perhaps most important of all, with different cards, codecs and settings to get to grips with, the learning curve is both steep and perilous and has led to video editing being seen as a dark and dangerous art.
Codecs are the secret that make computer-based video possible.
Not any more. The difference is the advent of DV (Digital Video). DV is a slightly confusing term as once any video has been transferred to a computer it's stored digitally. DV is just another encoding format, in this case built on an optimised MJPEG-based approach with both intraframe and interfiled, but not interframe, compression. What really makes DV different is that it is a single fixed standard. It was designed by a consortium of the major video manufacturers to work at a sampling resolution of 720 pixels per scan line (ie 720 x 576 for PAL at 25 frames per second, 720 x 480 for NTSC at 29.97 fps). This produces a fixed video data rate of 25 Mbits/Sec which equates to around 3.5 MB a second when audio, error correction and time code information is added.
The benefits that flow from the use of the DV standard are apparent throughout the video production workflow. Crucially it's practical to implement the hardware DV codec actually on the camcorder rather than on a board so that there is no initial analogue stage. This cuts out the need for conversion or transcoding which always involves some artifacting and loss of quality. It also cuts down on noise which not only improves quality, but also helps keep the file size down. The result is much sharper images than are possible conventionally.
DV also comes into its own when transferring to the computer as the video stream is already digital. This means there's no need for expensive £500+ capture cards let alone calibration and so on. All you need is an IEEE-1394 (commonly known as FireWire or i.Link) port which are increasingly built into PCs or are available as add-on cards for around £50. The transfer process is also a lot easier as the computer can control the camcorder through the IEEE-1394 cable which makes it much easier to line up the sections of tape you want to bring over.
With a DV camcorder and IEEE-1394 connection, video capture is simple.
Once the DV has been transferred to the computer its performance is equally impressive. Other codecs are more efficient at squeezing data but, crucially, DV's 3.5 MB/sec data rate is well within the real-time capabilities of most modern hard drives and, as it's fixed, there's no danger of a sudden spike exceeding bandwidth. You'll still need as much space as you can afford with DV taking up about 215 MB per minute, or 5 minutes per GB (and don't forget to factor in space for temporary files and the final edited version), but again these days that's feasible. In other words DV provides a ready-made quality/filesize standard ideal for video handling on today's computer systems.
DV has one final advantage - the edited digital video stream can be copied back to the DV camcorder. This means that there is virtually no "generation loss" through transcoding or the introduction of noise throughout the video capture, editing and storage workflow. Even better, it means that the typical 60-minute mini-DV tape can act as an excellent video output and archive medium offering the equivalent of around 12GB of easily accessible, re-recordable and cheap storage.
There's one slight problem here. European law treats camcorders with the necessary DV-In capability as VCRs which are in a higher tax bracket so that most budget camcorders have their recording capability deliberately factory-disabled! Thankfully time has moved on and, while we're still being forced to pay a premium, it's now possible to buy a camcorder with both DV-Out and DV-In at a reasonable price. This was clear in the recent PC Pro digital camcorder round-up and, with DV-In/Out devices now available for under £500 inc VAT, I decided that the time had come to invest (well it was Christmas).
There were two points that I swithered over, namely the importance of the ability to take still photos and of an analogue video input. Eventually I decided that even the best camcorder's photographic capabilities are still poor compared to a dedicated digital camera and that I could wait a few years to convert my existing tapes or hopefully borrow a friend's AV-enabled camcorder. A few days later I was the proud owner of the Labs-recommended Panasonic NV-DS28B.
First impressions were, and remain, very positive. To begin with, thanks to the compact size of mini-DV tapes (a twelfth of the size of VHS), the camcorder is reasonably small and light which is as significant psychologically as it is practically. The battery life is also surprisingly impressive especially when compared to my digital camera. The range of functionality is also good with a range of six preset exposure modes, manual focus/iris/shutter speed and white balance control, a good image stabilizer and even an infra-red mode for night shooting and Blair-Witch-style projects. Most impressive of all is the quality of the video from the ¼ inch 800,000 pixel CCD with the sharpness and the lack of noise leagues ahead of my analogue efforts.
Now all I had to do was plug the FireWire cable into my camcorder and into my Vaio's i.Link port and, thanks to the wonders of plug-and-play, I should be up and running. And amazingly that's exactly what happened - after the week it took me to realize that my cable was faulty. Within minutes of exchanging it, I had loaded Sony's bundled DV MotionGate utility and was happily controlling the camcorder and capturing video to disk without having to worry about codec settings or lost frames.
The process was so simple and straightforward that I felt I needed some DV-enabled editing software to match. In the past I've used Adobe's Premiere to good effect but I've always felt that it was rather like Photoshop - undoubtedly the best option for full-time professional users, but overkill for occasional use and simple projects. I therefore decided to take a look at a couple of budget and user-friendly alternatives - MGI VideoWave 5 and Ulead MediaStudio Pro 6.5.
Both of these offer surprisingly advanced features such as direct DV capture and control and intelligent handling where only those sections of a DV project that have been edited need to be rendered. MediaStudio is definitely the more powerful with its Timeline offering the ability to independently manage audio and to control multiple video tracks including overlays. It also offers batch processing, a dedicated vector titling package in CG Infinity and even a rotoscoping package for frame editing and painting in Video Paint. It's undoubtedly powerful and excellent value, but for advanced projects I'll still choose the security and familiarity of the Premiere/After Effects approach.
For simple projects though I will definitely turn to VideoWave 5. Like MGI's static photo editor, PhotoSuite, this offers a modern and interactive interface tailored to the consumer wanting to produce impressive results quickly. Rather than getting into the complexities of Timeline-based editing, VideoWave relies on a simple Storyboard where clips are dropped consecutively. For greater control you use the toolbox down the left of the screen to switch mode to capture video, trim clips, add titles, apply effects and losslessly copy your project back to tape on your DV camcorder.
VideoWave offers a clean and modern approach for simple projects.
And when you are ready, you simply hit the large Produce Video icon to output your video to a computer playback format for others to see. This is the end of the line as far as DV is concerned as its system requirements are just too high for it to work as an exchange format. Instead it's necessary to use a software-based codec to ensure that your video can be played back in real time on any supported platform. VideoWave makes this as painless as possible with a choice of the most common AVI, MPEG, WMV and RM file formats and frame size/rate settings presented as preset templates. And, where necessary, you can always create your own template and dig down to change codec and video settings.
For high quality computer-based delivery and playback both VideoWave and MediaStudio also offer an option I was particularly keen on investigating - output to DVD (Digital Versatile Disk not Digital Video Disk as it has nothing to do with DV). In the past the software necessary for this cost hundreds of pounds so to find it bundled in for free with editors costing well under £100 is seriously impressive.
The practice of creating your DVD in both VideoWave and MediaStudio Pro is straightforward but again, although it's pretty basic, I prefer the more modern and simple VideoWave approach. All you need to do is select the DVD icon and then, using the Mode bar and the Library, you create your menus by selecting a background image, dragging on your video clips, choosing a button style, applying a text effect and then hitting the Burn button to save the files to hard disk or to your recordable device.
DVD authoring is moving into the mainstream.
Burning can take a long time as saving to DVD's highly compressed and high-quality variable bit-rate MPEG-2 format takes a lot of processing and isn't a real-time process without dedicated hardware. The results though are generally well worth the wait. Best of all you can write around 20 minutes of video files to a CD-R as a mini-DVD and this will be recognised and played back by most recent DVD players. Alternatively you can save around 60 minutes of VHS-quality video to the lower resolution MPEG-1 format and create a Video CD (VCD). This means that anyone with a recordable CD can now easily and cheaply publish their own accomplished multimedia presentations.
DVD and CD-based playback is impressive but it doesn't have the universal reach of Web delivery and this is undoubtedly the biggest boom area for video publishing. The big question is: what's the best Web video format? Currently there are four main formats in wide use on the Web: the open MPEG-1, RealNetworks' RealMedia RM, Apple's QuickTime MOV and Microsoft's Windows Media Video WMV formats. Unfortunately there's no simple single answer as this depends on a whole host of interacting factors such as the market penetration of the player, the importance of cross-platform playback, the target bandwidth, the performance and cost of implementing streaming delivery and other factors such as the ability to embed a Flash track for interactive control.
There are plenty of Web video formats and settings to choose from.
Which format is best for you will vary depending on your requirements and resources and all formats can claim unbelievably large markets - but overall it's possible to get a picture of the way the wind is blowing and it's quite a familiar story. MPEG-1 wasn't designed with the Web in mind and can't compete with the streaming capabilities of the ever-changing proprietary formats; RealNetworks was the pioneer but alienated many users and is losing market share; QuickTime trail-blazed some exciting advances but is still seen as a primarily Mac-based solution; which leaves Microsoft eating up the market thanks in no small part to its bundling of Media Player with Windows. In other words it looks very much like a repeat of the Browser wars where the integrated Internet Explorer eventually saw off Netscape and the other browser developers.
It's always hard to bet against Microsoft but the war's certainly not over yet and the opposing forces are regrouping. Apple has announced that the video component of QuickTime 6 is going to move on from its previous reliance on the Sorenson codec and will instead be based on the open MPEG-4 standard which offers near MPEG-2 quality optimised for streaming Internet delivery at lower than MPEG-1 data rates in the range between 10 KBit/s and 1 MBit/s. RealNetworks has also endorsed MPEG-4 by announcing support through a plug-in. This should mean that an MP4 video will be able to travel the Web and play back on any supporting player on any platform.
Not surprisingly Microsoft also has its eye on the future and has responded to the announcements with one of its own. The forthcoming launch of the "Corona" version of its Windows Media technology is set to see a number of enhancements including a 20% boost in the overall efficiency of its codec. Where MP4 targets low bandwidth delivery though, Corona is primarily aimed at the higher end. Here it aims to provide a true broadcast-quality experience for broadband users with new server and encoding software and a feature called Fast Stream that eliminates the need for buffering of streaming audio and video files to give an "instant on" channel-surfing TV-like experience.
Crucially Microsoft is also aiming Corona at the DVD market promising a 4:1 compression advantage over MPEG-2 which will enable a single DVD to hold all the Godfather movies or a CD to hold over an hour's worth of high quality video. Corona is also targeting video quality with a move into home cinema-style surround-sound and high definition HDTV with the ability to playback 720 x 1,280 video at 24 fps - providing "twice the quality in half the space". And 90% of DVD chipmakers have already announced support.
Before seeing both in action it's impossible to say which will win out between MP4 and Corona, let alone to guess who will win the battles of the future. Undoubtedly though the move to HDTV and surround-sound will eventually affect all aspects of computer-based video and in time some superior standard will take over from DV - hopefully providing a single video format that embraces camcorder, computer, CD/DVD and broadband Web. That's a few years off however, and in the meantime I'm more than happy with the huge advances represented by today's technologies and especially DV. If you are interested in graphics, design and publishing, there's nothing to stop you putting video to work already.
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