Avid DNxHD

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Avid DNxHD is a lossy high-definition video post-production codec engineered for multi-generation compositing with reduced storage and bandwidth requirements. It is an implementation of SMPTE VC-3 standard.[1] DNxHD codec was developed by Avid Technology, Inc. It is comparable with Apple's ProRes 422 which uses similar bit rates and has the same purpose.
Uncompressed high definition digital video has a substantially higher bitrate than standard definition and can require powerful computers to process and edit. Other codecs such as HDV, DVCPRO HD, AVC-Intra, AVCHD, and HDCAM use compression techniques that limit the spatial and temporal resolution of the image. While suitable for acquisition, these codecs will tend to degrade the image over the multiple encode-decode cycles that are typically required during the post-production of complex layered imagery.

DNxHD offers a choice of three user-selectable bit rates: 220 Mbit/s with a bit depth of 10 or 8 bits, and 145 or 36 Mbit/s with a bit depth of 8 or 10 bits.
DNxHD data is typically stored in an MXF container, although it can also be stored in Quicktime or AVI containers. A standalone Quicktime codec for both Windows XP and Mac OS X is available to create and play Quicktime files containing DNxHD material. There is also an experimental support for DNxHD in open source FFMPEG project.

DNxHD is intended to be an open standard, but as of March 2008, has remained effectively a proprietary Avid format. Ikegami's Editcam camera system is unique in its support for DNxHD, and records directly to DNxHD encoded video. Such material is immediately accessible by editing platforms that directly support the DNxHD codec. The source code for the Avid DNxHD codec is freely available from Avid for internal evaluation and review, although commercial use requires Avid licensing approval. It has been commercially licensed to a number of companies including Ikegami, FilmLight, Harris, JVC, Seachange and EVS[1].

DNxHD was first supported in Avid DS Nitris (Sept 2004), then Avid Media Composer Adrenaline with the DNxcel option (Dec 2004) and finally by Avid Symphony Nitris (Dec 2005). Xpress Pro is limited to using DNxHD 8-bit compression, which is either imported from file or captured using a Media Composer with Adrenaline hardware. Media Composer 2.5 also allows editing of fully uncompressed HD material that was either imported or captured on a Symphony Nitris or DS Nitris system. On February 13, 2008 Avid reported that DNxHD was approved as compliant with the SMPTE VC3 standard.[2]