| Page (1) of 1 - 02/16/07 |
 email article |
 print
page |
|
The tools of cinematic production in the digital age are often celebrated as adhering to the much touted 'trickle-down' effect whereby the high-end inaccessible tools of yesterday are the common indie producer's tools of today. This is of course evidenced in a range areas from compositing to 3D graphics, from high-definition to real-time editing systems; all once the domain of dedicated hardware systems and now perfectly at home on a laptop.
But the trickle-down idea of technological power flowing from the few to the many; from the big-budget to the no-budget, really only tells half the story. With this technological ebb and flow also comes a perspective shift in expectations and ambitions of filmmakers and, by proxy, the expectations of viewers. Where once the small-studio or indie producer would have been simply happy with a system capable of putting their shots in the right order; now the availability and accessibility of formats and modes, previously out of reach, has raised the bar on the quality and complexity of what small productions expect to create and deliver. So it is that, just when beloved acronyms like DV and HDV seem well embedded and a hand-held $5000 camera shooting Standard Definition makes the biggest Australian movie hit for ages in the form of 'Kenny', we see the rise of viable uncompressed SDI post-production for the indie studio.
For the uninitiated, SDI stands for Serial Digital Interface and is a standard protocol for transfering and capturing uncompressed video material for post production. Long the staple of electronic news gathering and DigiBeta format productions, SDI hardware is now increasingly finding its way out of the broadcast studio and into smaller production houses and indie studios. Where once the hardware requirements for working with uncompressed video material were prohibitive, a number of hardware developers are now aiming directly at lower-budget users and leveraging the massive computational power of current computer workstations fitted with multi-core processors.
Leading this charge for sometime has been California-based AJA Video Systems. The company?s latest release is the Xena line of 8bit and 10bit uncompressed HD/SD SDI capture cards. More than simply another step in a long line of similar hardware tools, the Xena pushes at the trickle-down boundary further by offering a high-end hardware solution that integrates tightly using plug-in protocols into the widest possible range of software tools; in some cases software applications that cost a fraction of the Xena hardware itself.
Australian based supplier of AJA products, Adimex, provided DMN for testing a Xena LHe card with Break-out box fitted into a certified HP XW8200 dual-Xeon workstation and a SanMan RAID storage array. This monstrously fast and powerful system together comes in at around A$15000 all together making it more than viable for outright purchase for a small studio and proportionally cheap to rent/hire out.
Before getting to how well the card and its associated software worked its worth first considering what the benefits of Uncompressed SDI are. The overwhelming majority of video formats in use both at the low and high end of the spectrum acquire in some form of compressed state; humble DV uses 5:1 compression, HDV uses Mpeg2 long GOP compression and similarly XDCAM also uses Mpeg, even DVCProHD and HDCAM both use various modes of compression in colour sampling, temporal compression and resolution ? so to declare that 'Compressed = Bad' and 'Uncompressed = Good' is a gross simplification that doesn't stack up to real-world production.
So why uncompressed? And indeed what are the advantages of shooting in a compressed format but capturing to your editing system as uncompressed? These are two questions and so have two answers, both of which center on the notion of an 'acquisition' format and and 'production' format and that there are distinct advantages to them not necessarily being one and the same.
In the broad picture, the advantages of an uncompressed video signal is simply the avoidance of any of the problems caused by compression; motion artifacts, blockiness, colour loss. The downside is the massively increased file size and data-rate of uncompressed images. They are simply too unwieldy and impractical unless you have very serious hardware to store them and push them around. The more significant question is to whether there is a noticeable difference between the two and this is where a consideration of what you're planning to do with the video enters the picture.
If you're planning on lots of colour grading, lots of motion-based effects and filters, if you're planning on lots of keying and compositing then all these processes draw upon the colour and frame information in the video signal - and a compressed signal is a starved signal...! On its own it may look fine but start trying to blend it, warp it and generally mess with it and you'll quickly see the warts and cracks appear in your video image. Performing these sort of manipulations on an uncompressed signal however can give much better results because there is simply more colour information and resolution to play with ? sharper keying, smoother colour grading.
That said, most productions short of those of George Lucas and Michael Mann, wont be shooting 4:4:4 uncompressed images anytime soon and so the acquisition format is invariably going to be a compressed one; HDV, XDCAM, DigiBeta, DVCProHD and so on. When your source is compressed the damage, so to speak, is already done so what are the advantages then to capturing uncompressed?
There are in fact a number of advantages to uncompressed capture of compressed source footage. On a simple level you give your footage a significant amount of post-production 'headroom' for while you can?t and won?t increase the quality of your footage by capturing uncompressed via SDI (which can expand the colour sampling to 4:4:4 instead of the 4:2:2, 4:2:0 or 4:1:1 of compressed sources) you do allow a level of data-space for the application of effects and composites ? literally there is more room to move in the file because its colour space is enlarged and data-rate increased. Even from a compressed aquisition, compositing and colour grading uncompressed video in post can yield significant improvements over the same processes on the native material.
The second major advantage is in output. At the end of uncompressed post you have an uncompressed master ready for telecine to 35mm for projection, HDCAM SR master tape or any other output without any compression-on-compression taking place.
There is also a hidden gem in current model HDV cameras that opens a whole new element to SDI uncompressed production with compressed format cameras. Many HDV cameras (namely Sony's A1, Z1 and V1 as well as Canon's XL H1, G1 and A1) have either Component or direct SDI output connectors that bypass the camera's internal MPEG 2 compression processing. What this means is that it's possible with these small HDV cameras to shoot fully uncompressed video directly output from the camera to a Xena SDI capture card, into a computer and written to the hard drive. While this might be logistically impractical in the field or even on location, it is certainly viable in a studio or sound-stage environment ? particularly for chromakey/greenscreen work ? all the advantages of keying uncompressed HD acquired on a camera that probably costs less to buy than the studio space is to hire.
So this brings us to the Xena LHe. The Xena is more than just an interface box for an SDI signal to flow, it?s really designed much more as a complete system form ingesting, managing, encoding, previewing and outputting uncompressed video material and in this regard stands as a very complete and cost effective SDI solution.
The Xena LHe hardware itself offers SDI input/output (at 8bit and 10bit) of standard definition and high-definition as well as analogue component I/O. Audio is handled by the embedded 8 channels of SDI audio or 2 channel balanced analogue audio. But central to the Xena's effectiveness is not so much the hardware itself as the software and application integration that accesses it. The Xena provides plug-in integration and direct support for a very wide range of applications, including Adobe Premiere Pro, Sony Vegas, Photoshop, Autodesk Combustion and After Effects, and in doing so not just provides access to the hardware via these software tools but also adds functionality to them. For example After Effects does not have any video capture functionality of its own but with the plug-in for the Xena hosted within After Effects a new capture utility is added that allows for direct capture from the source via the Xena straight into your After Effects project.
The Xena however also possesses its own software system for capture and conversion of SDI video streams. Known as Machina, this software utility, which functions as a stand alone tool independent of any host application, provides a comprehensive set of capture options. Most notably of these is the capability to capture natively and directly from the Xena into a wide variety of file formats and wrappers, including QuickTime, AVI, Targa and Tiff image file sequences as well as Cineon for 2k film resolution. The only issue we discovered with this in testing was that footage captured to an AVI wrapper needed to be written as separate files for video and audio. Not of itself a major deal as highly accurate timecode ensures that re-syncing of audio and video is a very simple affair but it is certainly an extra step that you could do without. The Xena had no such issue with writing to a QuickTime wrapper.
The Machina software is very straight forward to use with a clear flow of choices for ingesting, monitoring and outputting your project. But the interface design of the software is one of those dreaded tools that skins over the top of the generic Windows interface with its own colour scheme and operational graphics. Sticking to a conventional Windows OS skin would be a much simpler and much better choice rather than trying to re-invent the interface wheel.
AJA supply its own 8bit and 10bit CODEC with the Xena for writing to QuickTime with superb quality and functionality. This CODEC, once on your system, is then available for any video application that can read QuickTime (which is of course pretty much all of them). In effect this means that with the Machina software for capture the resulting files can be used freely in any application on your workstation and not just those that have support for the Xena card or function with the Xena plug-in. This is a very effective way to ensure that Xena hardware is a viable SDI solution regardless of what software you're using or how many machines you are sharing across in a studio.
 |
| XENA capture from After Effects |
In the current climate, where the shift to HD is not 100%, a large variety of projects need to flexibly move and switch between SD and HD resolutions. Here the Xena offers superb hardware-based 10bit HD to SD conversion that manifests itself a number of ways. Footage can be down-converted on capture from HD to SD, HD footage can be monitored in real-time to an SD monitor and SD copies can be directly run off from a HD master. The HD to SD conversion can be applied to any and all inputs and outputs on the Xena card and functions incredibly effectively in a mixed resolution environment.
In the current climate not only is format and resolution of key significance but also frame rate where variables have never been so wide resulting from the diversity of SD and HD delivery and production formats. Here the Xena shows its well round and versatile qualities freely handling all and sundry ? 25p, 50i, 30p, 29.97p, 24p, 60i and 23.976p.
Of course all this, on the right system, makes SDI uncompressed production seem like the only way to go. Certainly the advantages of uncompressed for those working in visual effects production or projects involving a high degree of post manipulation are obvious. But what mustn't be forgotten is that the quality of an image is 90% dictated by the quality of the lens in the camera. Everything else you do to the image from capture, to effects, to output is subservient to that first image process of the lens. Working with uncompressed footage from a camera with a crap lens on a set with poor lighting is not going to provide a great deal of benefit.
It also must be said that where once SDI capture was the only way to go across the board for high-quality moving image ingest and production it is now arguably regulated to a more specific role; one where its strengths are exploited for specific purposes rather than being the generic standard of ingest. Some may well ask if SDI is the 'past' rather than the 'future' of digital production? The incredibly high quality of compressed formats such as HDV and XDCAM and their respective cameras (whose optics and qualities are only getting better) along with the ultra efficiency of Firewire has drastically altered the need, or perhaps even desire, for SDI as a standard ingest method.
What can be said with some certainty is that whilst many productions will find no discernible or tangible benefit to an uncompressed workflow over a compressed one, those seeking to exploit the evolving nature of the moving image where expectations for the visual extraordinary are only growing, will find enormous benefit in hardware such as the Xena LHe.
The sheer flexibility of this product and its robust manner of dealing with mixed resolution environments makes it a superb choice for small studios and indie producers (and even large production houses for that matter) seeking to exploit every last frame and pixel of an image.
Page: 1
Mike Jones is a digital media producer, author, educator from Sydney, Australia. He has a diverse background across all areas of media production including film, video, TV, journalism, photography, music and on-line projects. Mike is the author of three books and more than 200 published essays, articles and reviews covering all aspects of cinematic form, technology and culture. Mike is currently Head of Technological Arts at the International Film School Sydney (www.ifss.edu.au), has an online home at www.mikejones.net and can be found profusely blogging for DMN at www.digitalbasin.net
Related Sites: Digital Producer , Media Workstation , Digital Video Editing , Audio Video Producer , BN - Broadcast Newsroom , Corporate Media News , Digital Post Production , DVD Creation , Presentation Master , Oceania , BN - Hardware , BN - Facilities
Related Newsletter: DMN Newsletter , Timeline Newsletter , KNews Newsletter , Digital Media Net , DMNForums , Review Seeker
To Comment on This Article, Click HERE
Most Recent Reader Comments:
Click Here To Read All Posts
Must be Registered to Respond (Free Registration!!!, CLICK HERE)
Vegas Pro 8 + Free Vegas Seminar Series
With 17 Reviews.
With 17 Reviews.
With 19 Reviews.
