FCP to Avid Workflows

I am often asked to edit TV programmes in Final Cut that will be finished in, or at least will somehow pass through an Avid system. This workflow is actually very straightforward, but can go horribly wrong if you don’t understand the different ways that Avid and Final Cut/Quicktime handle video. There is a lot of great information out there on the web, but also a lot of disinformation – with Avid fans dissing FCP and vice versa – so as a user of both, I thought I would try to draw it all together into one blog entry.

Let’s say you finish your edit in FCP and output a ProRes 422 Quicktime. Your file will be tagged with information on the colour space the video is encoded in. If you use the Finder to ‘Get Info’ on your new ProRes file, it should look something like this:

ProRes Info

Note in the ‘More Info:’ section the Color Profile is HD (1-1-1)

The options you could see are:

1-1-1: HD (Rec. 709)
6-1-6: SD(SMPTE-C)
5-1-6: SD (PAL)

So, with this file, Quicktime knows to set the color space, gamma and so on to be suitable to correctly(ish) display Rec. 709 video on your computer screen, irrespective of the display gamma you have set.

If you ‘Get Info’ on a DNxHD Quicktime generated by Avid you’ll see something like this:

DNxHD info

This time, there is no Color Profile information, so Quicktime doesn’t know how to display this video. It’ll have a go, but it will be wrong, and it will be differently wrong on different computers - for instance, Mac OS X 10.5 and earlier used a system gamma of 1.8, 10.6 and above use 2.2. Rec. 709 (sort of) has a gamma of 2.35 (in Europe) or 2.4 (in the USA).

This comes down to a fundamental of the way Avid works. Avid has always been intended to be used with an external, broadcast monitor, so what is displayed on the computer monitor isn’t intended to look ‘right’. In contrast (pun intended), FCP intends that you see the ‘right’ answer on the computer monitor though, to be honest, even if it worked properly this is a flawed concept as you really need a calibrated broadcast monitor anyway.

So much for Quicktimes, what does this mean in transferring video from FCP to Avid?

Firstly, and most importantly, if you ‘Import’ a ProRes Quicktime into Avid you will get the wrong answer! Both the gamma and the colour information will be incorrect.

Remember that Quicktime expects to convert the raw data in the file to the appropriate colour space as it’s displayed, using the Color Profile tag. Avid, however, assumes that the raw data in the file is correct, and doesn’t perform any conversions, so when it reads the file it gets the wrong answer.

Fortunately, if your Avid Media Composer is later than 3.5, you can use Avid Media Access (AMA) plug-ins. Don’t ‘Import’ the Quicktime footage, just link to the file using AMA. The AMA plug-in uses Quicktime to read and convert the footage, providing Avid with the corrected, raw data it is expecting.

All well and good, but what about a DNxHD Quicktime file output from Avid?

This file will have two essential problems. As we have already discovered, it won’t have a ‘Color Profile’ tag, so Quicktime won’t know how to adjust the video to suit your computer monitor. Secondly, we have to take into consideration Avid’s video range.

To cut a long story short, Avid uses the broadcast standard of black being nominally translated to a digital value of 16 (8-bit) and white being 235. Your computer expects black to be 0 and white to be 255. There’s a bit of complication because a computer (and most other displays) use RGB and broadcast uses YUV, but the specified matrix that converts one to the other doesn’t change these levels.

So, as well as the gamma and colour profile of the video being wrong, black will look like a dark grey, and white will be some Dulux shade of ‘off-white’.

Avid does provide a setting to expand (on export, or contract on import) these levels, but for broadcast work you never/rarely want to do this.

On the plus side, you can ‘Import’ a DNxHD Quicktime into an Avid and get correct levels and gamma.

There is another gamma related wrinkle, whilst we are talking about Final Cut. If you import a still image into FCP, the chances are that its gamma setting will be ‘Source’, as in this example:

FCP Still Properties

You’ll need to change this value to 2.35 for HD, or your stills will look washed out (as the default gamma is 1.8).

So, that’s enough rambling. What does it mean to your FCP to Avid workflow?

  1. It’s fine to generate a ProRes (or similar) file from FCP if you are moving it into Avid, but remember you must use AMA to get the file into Avid - don’t ‘Import’ it.
  2. If you want to export a Quicktime using the DNxHD CODEC, don’t be frightened if it looks a bit odd played back in Quicktime. If you import it back into FCP it will be wrong.
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