High definition (HD) is the star of the moment. In fact, the last edition of the NAB had her as the main protagonist. However, when we try to bring the concept to everyday work, we notice that the delights of this new world are sometimes clouded by bandwidth requirements, which can reach almost 1200 Mbps, and storage capacity, which are getting higher, more expensive and difficult to manage.
To alleviate this conflict, different coding systems have emerged, and continue to emerge. One of them is DNxHD, a technology developed by Avid that allows post-production tasks to be carried out in HD, but with technological needs similar to those of the universe of standard definition (SD, Standard Definition).
For example, this technology works in a 4:2:2 color space. It supports the different formats of HD projects (720 p/60, 1080 p/i at 30, 25 and 24 frames per second, among others). This means that it offers more than 15 possible resolutions with that sampling. In addition, it is available in three bandwidth configurations: 220 Mbps (for 10-bit video), 220 Mbps (for 8-bit video), and 145 Mbps (for 8-bit video). Just as a comparison, it can be noted that uncompressed standard definition 8-bit video requires about 200 Mbps, which follows that the performance is much more than acceptable.
Moreover, this decoder provides support for the most widely used native HD formats. And if the concern is quality, it is valid to clarify that this technology eliminates the resolution losses of the conversion of a format before compression.
Exchange times
One of the conflicts that arises whenever a technology like DNxHD appears is to what extent it can become compatible with similar ones. In the specific case of the Avid encoder, it uses the MXF (Material Exchange Format) standard, which allows a direct exchange of materials with any product of other brands, as long as they support this standard.
As a complement, Avid also introduced DNxchange, an input/output device that allows channels to work with HD material without having to update their digital interfaces (SDI) or standard definition routers , as it makes it easier to convert the HD-SDI signal (from cameras, switches, routers and decks) in DNxHD content. Once the conversion is done, there is a free way to pass the HD material through the existing SD-SDI infrastructures. This tool is very useful for the deployment of HD in broadcasters that do not want to make large infrastructure investments in the short term.
Those who use Media Composer Adrenaline HD can now use this technology, installing the Avid HD extension on Avid Adrenaline Digital Nonlinear Accelerator. Those who have DS Nitris, will receive it as part of a free upgrade. In all cases, thanks to SD-like storage bandwidth requirements, collaboration and material sharing over a Storage Area Network (SAN) is possible.
Even Xpress Pro users have the possibility to incorporate DNxHD and work in HD, achieving great image quality even after multiple generations and with the ability to export directly to Windows Media 9 (MWD HD). With this tool it is possible to play and render DNxHD materials in local storage.
One of the pioneers in the implementation of DNxHD has been TF1, the French television, which adopted this technology for its post-production process in high definition, after acquiring a DS Nitris system and eight Media Composer Adrenaline HD editors. TF1 is one of the driving forces behind high-definition television across Europe and is committed to its broadcast. In Argentina, he was employed by Artear (Canal 13) for his HD miniseries, "Sin código".
One more alternative so that high definition does not also mean high costs and great difficulties.
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