So, we decided to move to DNxHR. DNxHR is the new codec family developed by the engineers at Avid. After years relying on ProRes for our post-production workflows, we are jumping ship… but it’s no big deal. Really! Here’s a little article that explains why we are embracing this new technology and why you should too.
One codec to rule them all
Avid released its first open codec, DNxHD, as a response to the different HD codecs used in tapeless cameras. At the time there was no AMA (Avid Media Access) so users had to transcode everything to a single codec to get rid of the Long-GOP, the weird rasters and the heavy compression. Avid had many versions of the codec that were used for editing, finishing or delivering in HD.
Apple also had the same problem and eventually came up with the ProRes family of codecs. These I-frame codecs were easy to understand, resolution independent, and quickly adopted in tons of professional software and hardware solutions. ProRes also had the advantage of working much better with log-encoded footage. That’s why Arri chose it for the default codec in the Alexa and that most external recorder offer ProRes recording as a base option. It even forced Avid to certify the use of ProRes for native editing in Media Composer.
Made for 4K
With the growing demand for 4K deliveries, Avid had to find a way to offer its users a solid 4K codec. Their DNxHD family was only good for HD. They worked hard on creating a reliable, fast and small codec that could sustain the heavy bandwidth and size of the 4K frames without losing the software’s responsiveness.
In september 2014, they announced a new family of codecs for that purpose: the DNxHR
Here at CineGround, we don’t even use Media Composer that much. We mainly launch it once a month to conform projects edited on it by our clients. So, this wasn’t the main reason to explore this new solution.
Without any update from Apple for our 2013 black Mac Pros we had to move our 4K room to Lenovo Windows workstations to continue to give a decent service to our clients. With the acquisition of an 8K RED Epic-W camera, the hit on hardware was more than brutal but clients were still expecting a smooth and fast post-production workflow.
As we relied heavily on ProRes for our editing, color grading and finishing, we had to rethink our workflow. The main reason was the lack of support for ProRes on Windows PC. The problem is that none of the majors NLEs, color grading software or compositors available on PC have support for ProRes export. Most of them will read ProRes but not a single one will be able to export a ProRes movie. This means no ProRes proxies for raw footage, no ProRes export from the color grading suite for the online and no ProRes masters for the clients. This really was a problem for us. Until we discovered DNxHR.
On PC and MacOS
DNxHD was developed by Avid. Unlike Apple, their software run on both Mac and PC. So the codec is available on both operating systems. You don’t even need to install Media Composer to use DNxHR, Avid have free codec installers for Windows and macOS.
Avid also allows 3rd party developers and even competitors like Adobe, Apple and Blackmagic to use it.
Since september 2016, the 5 flavors of DNxHR are available as a source and export codec in Adobe Premiere and After Effects. They are supported in QuickTime (.mov) and in Material Exchange Format (.mxf) wrapper. Adobe even wrote its own playback engine for DNxHR.
Blackmagic supports DNxHR as a source, export, render and cache format since 2015. DNxHR 444 is one of the few codec they recognise as HDR-worthy, meaning that it can be use as a digital intermediate codec for camera originals without clipping highlights and shadows. It can also take the heavy bending required by HDR deliveries.
If you are using QuickTime based software like Final Cut Pro 7 or Final Cut Pro X, you can use the free installer that gives you access to the DNxHR codecs so that you can read the files in mostly any software available.
Whatever the wrapper
The DNxHR codecs are “wrapper independant” which means they can be used in a QuickTime wrapper (.mov) or an Material Exchange Format (.mxf). These are the two main wrappers used in professional video softwares. This also means that you generally can switch between wrappers without having to recompress to the same codec. If you ever have to switch wrapper, most software will only have to do a quick rewrap that won’t affect the quality of the embeded image in any way.
DNxHR is not just an efficient codec, it’s a fast codec. Compared to other similar codecs, it threads better. This means it can be more efficiently decoded by CPUs. This give the user more processor cycles to do something else like real time color grading or VFX. It also has a big impact on multi-camera edits.
If you computer needs a little boost with those big 4K DNxHR-encoded images, Avid even offers hardware acceleration for quick real time encoding on capture. The DNxIO (http://www.avid.com/products/avid-artist-dnxio) is a capture and playback interface developed by Blackmagic Design for Avid. It offer onboard DNxHR encoding for enabled softwares like Media Composer.
Good on set too
DNxHR is also widely
used available onset. Camera manufacturers like Sony, Panasonic, Arri and RED are now offering it as a recording codec directly in their cameras. Most video recorders out in the last two years also offer the option to record uncompressed HD and 4K camera feeds in DNxHR for more efficiency.
All around codec
Right now, DNxHR is the only codec family available throughout the whole production and postproduction, on both Mac and Windows and available natively in all the major post-production applications out there.
DNxHR is far more versatile than the original DNxHD. There are 5 denominations that can all be used in HD and 4K in whatever frame rate you need. Here is a quick chart showing the different flavors:
|CODEC||Bit Depth||Color sampling||Alpha support||Usage|
|DnxHR 444||10 or 12||RGB – 4:4:4||yes||Finishing / Cinema delivery|
|DnxHR HQX||10||4:2:2||no||UHD broadcast delivery (12bit)|
|DnxHR HQ||8||4:2:2||no||UHD broadcast delivery (12bit)|
|DNxHR SQ||8||4:2:2||no||HD and SD broadcast delivery|
|DnxHR LB||8||4:2:2||no||offline editing|
These are I-frame codecs meaning that each frame have info for every pixels and are independent from the previous and next frame. So depending on the frame size and the frame rate, you’ll get different file size and bitrate.
DHxHR bitares un MB/s
|Resolution||Framerate||DnxHR 444||DnxHR HQX||DnxHR HQ||DnxHR SQ||DnxHR LB|
|1920 x 1080||23.98||41.68||20.79||20.79||13.77||4.31|
|1920 x 1080||29.97||52.10||26.00||26.00||17.21||5.39|
|2048 x 1080||24.00||44.39||22.20||22.20||14.70||4.59|
|4096 x 2160||24.00||177.67||88.88||88.88||55.07||17.14|
For all those reasons, we will now use DNxHR for our dailies, intermediates, renders and masters. It gives us a more streamlined streamlined workflows with less variables. And since we work on all our projects hand-in-hand with our client, this decision will accelerates the transfers, the technical discussions and make every steps more efficient.
Colorist & Post Supervisor @ CineGround