4 minute read
A mezzanine workflow is a kind of offline workflow that can provide a smoother editing process than editing directly from the camera files.
The most common offline workflow is a proxy workflow, where you use smaller, low-quality files to edit with and then reconnect back to the camera files afterward.
With a mezzanine workflow, you transcode your camera files into a codec that is both good for editing and very high-quality (not very lossy). Because the codec is very high quality, almost all of the original information from the camera files has been preserved, and so it’s not necessary to re-link back to the camera files – you can just export directly from the intermediate files or hand them off to your color correction team.
There will be some theoretical loss of information when you transcode into this codec, but if you pick a good enough intermediate codec, the difference will be small enough that you don’t need to worry about it.
Part of the reason why the Mezzanine workflow is common is because it used to be a lot harder to use a proxy workflow. Some of the major software providers didn’t make it particularly easy to relink back to the original camera files, and so people would choose a Mezzanine workflow for the simplicity. Nowadays, however, the offline/online switch is pretty easy to do in any editing package.
One exception could be when you have a lot of mixed footage types. If you have multiple frame rates and frame sizes in the same project, switching back and forth from the proxies to the capture codecs can be a headache. A mezzanine workflow solves that problem.
If you are using some third-party tools to help prep and organize your footage before you start cutting, those can also make the relinking process more tricky with a proxy workflow. One common example might be software that automatically syncs audio tracks or multicam shoots.
One downside to the mezzanine workflow, however, is that you can’t “bake in” the LUTs for your editor – you’re going to need to apply a LUT via a color-correction effect in your editing software. If you were to include the LUT in your transcode for Mezzanine workflow, you would be losing all of the benefits of recording in log in the first place.
The other obvious downside is that you need to store all of these (much larger) files while you’re editing, and you will also need higher-speed storage than you’d need with a proxy workflow.
The key to picking a good Mezzanine codec is to make sure that you are preserving all of the information from your capture codec. An intermediate codec will never make your images better (more detailed explanation below), but it can definitely make them worse if you choose the wrong codec. The important thing is to understand the details of your original footage and make sure that your intermediate codec is at least as good as your capture codec in each area. If you capture your footage on a DSLR like a Sony A7Sii at 4K, then you will be recording in a 4:2:0, 8-bit, Long-GOP codec at 100Mbps. You want an intermediate codec that is at least 4:2:0 and 8-bit. Going beyond these values (e.g. to 4:4:4 and 12-bit) won’t hurt, but it also won’t help at all, so it’s probably not worth the extra storage space.
Let’s say, for example, that we want to go with a ProRes codec. We have 4 options to choose from that are 4:2:2 and 10-bit.
145Mb/s ProRes 422 Proxy
328Mb/s ProRes 422 LT
471Mb/s ProRes 422
707Mb/s ProRes 422 HQ
You might think that all you need is to match the camera bitrate (100Mbps), but you actually need to greatly exceed the camera bitrate. This is because h.264 is a much more efficient codec than ProRes. Because h.264 uses long-GOP compression, it can pack a lot more information into those 100 megabits than ProRes can. In order for ProRes to match the image quality of h.264, you need a much higher bitrate. We would recommend only using ProRes 422 or ProRes 422 HQ if you’re starting with a 100Mbps h.264 codec. ProRes 422 will probably do just fine, but if you have lots of storage space, then going up to ProRes 422 HQ will have a slight edge.
While it’s fine to simply match the bit-depth and color sampling when choosing an intermediate, you should always increase the bitrate at least a little. If you’re going from long-GOP to a non-long GOP codec, then you should increase the bitrate a lot.
Side note: If you wanted to go with DNxHD instead of ProRes, you have similar options, except that DNxHD also offers an 8-bit version for the lower-end codecs. Since our footage is 8-bit to start with, that won’t hurt us at all.
Video collaboration solved.