If you use any external display to view video files in Pro Tools, it’s important that you take into consideration video latency — the delay between video being output by Pro Tools and appearing on a screen. This will be different depending on which method you use to view your video file and what device you use to view it with. For example, some people use video projectors, which tend to have a higher latency than other display devices. Why does this matter? Well, if you are trying to get things in sync with the video and the video you are viewing is delayed, then all your carefully positioned ‘hit points’ will be out of sync on the finished product and you will have a very unhappy client on your hands! Note that video latency is an issue with both TDM and LE systems. Pro Tools has a feature in the Movie menu where you can compensate for this latency to make sure everything is bang in sync, but first you need to know how much compensation to apply!
There are some extremely useful documents on the amounts of latency on the different systems at the Pharoah Editorial site. Richard Fairbanks compares all the different options outlined above with their relative performance and has been very supportive on the Digidesign User Conference on these matters.
What you need
In terms of the materials needed to work to picture in Pro Tools, you will encounter three basic elements, some or all of which will need to be delivered to you. First, you’ll obviously need the movie file. Second, you’ll want an EDL (Edit Decision List) from the video edit, if one exists. This is a list that records how and where the video was edited. Third, there is what’s called ‘sync audio’, if any exists for the project you’re working on. Adverts, for instance, are often shot ‘mute’, with all sound added in post-production.
This workflow has been made a lot simpler with the introduction of electronic delivery of these elements. Before, you would get the video and audio on tapes which would then need digitising and loading into your audio editing system, and then the EDL (which often used to come on a floppy disk) would be used to ‘conform’ the audio material to match the video edit against the original timecode data from each edit. This process is rarely plain sailing, and is thankfully less common these days.
The EDL now more often comes in the form of an OMF (Open Media Framework) file: there are other formats like AAF but the OMF format is still the most common one. These are interchange standards that enable the user to import, edit and export information to and from different brands of editing station, whether video-to-audio, audio-to-audio or audio-to-video.
OMF files can come in two types, ‘embedded’ or ‘referenced’. An embedded OMF is one large file that includes all the audio used in the project and the EDL consolidated into one file. A referenced file is where the OMF file is simply the EDL data, which then points to all the individual files, in the same way as a Pro Tools Session does. The down side of the referenced format is that it is very easy to lose a few files in the transfer process, and I always ask for an embedded OMF file. These can easily be created from video workstations like Avid or Final Cut Pro. If the video editor is unsure on how best to handle the OMF export, there are loads of help guides available on the Internet. We will be drawing up some useful guides to help, watch this space.
How they come
The OMF and video files tend to be delivered on DVD±R or on a portable hard drive as the DV video files can be quite large — around 200MB per minute of video. My last project came in at over 50GB of data!
Note that if the file is delivered to you on a DVD±R, you’ll need to copy it off onto a hard drive before trying to import it into Pro Tools. Put the DV movie onto a different drive to your audio files — your boot drive will be fine if you don’t have another drive other than your audio drive. While you’re on the ‘phone to the client, try to make sure they send video with ‘burnt-in’ timecode. This is where the timecode is overlaid, in numbers, on the video so at any point you can see the exact timecode point. This is very useful to check that the video file matches the Pro Tools timeline by going to the end of the video track and comparing the burnt-in timecode with the Pro Tools counter.