• Blogs
• Forums
• Tradeshows
• Partners
• White Papers
• Events

HDV Editing Using Avid’s Liquid 7.1, Part 1

Jul 10, 2006 4:46 PM, By Steve Mullen

What would it mean to your HDV editing workflow if you could insert multiple video formats into a Timeline? I found one answer to this question when I spent several weeks working with Avid's Liquid 7.1.

The question is a natural follow-on to most of what has been covered in the last few months in HDV@Work. When we looked in depth at interlaced HD and how it was processed by progressive displays, the issue at heart was converting one HD format to another. In the last few issues of HDV@Work, we explicitly examined the topic of media conversion when I dealt with the use of legacy video. Nevertheless, we never really addressed how various media could be brought together.

If one is working with Final Cut Pro, the solution is to convert the different video formats to the format you will use for editing the majority of your source material. With Liquid, the solution is far simpler -- simply edit with little, or no, regard to format. Right now, I have two HD sequences on my PC. One sequence was created as 720p30 HDV while the other sequence was created as 1080i60 HDV.

The 720p30 sequence contains: 720p30, 720p24 (yes, 24p), 1080i60, 16:9 DV, 4:3 DV, and 4:3 MPEG-1 shot with a cellphone in Malaysia. (I included the latter because it showed Muslim women and their kids enjoying a Christmas exhibit at a shopping mall in Kuala Lumpur at the same point in time when such exhibits were considered by some in America as “offensive” to non-Christians.) The screenshots below show how I customized Liquid's toolbars to meet my editing needs.

The 1080i60 sequence begins with multiple Sony Z1 clips followed by the entire 720p sequence. I simply dragged the 720p sequence from Liquid’s Sequence Rack (bin) into the 1080i sequence.

My goal is to record the first sequence to HD1 (720p) and the second to HD2 (1080i), plus create widescreen DVDs and widescreen DV tapes from both sequences. Everything is ready for export.

Of course, we are way ahead of ourselves in this odyssey. We need to go back to NAB, where I saw an excellent demo of Liquid. I wound up watching the demo as a way to relax after learning Avid and Apple were not yet supporting 720p24 or 1080 24F. The demo quickly took my mind off 24fps. It was clear that Liquid had undergone a beneficial revision of its human interface.

Over almost a decade, I have reviewed what is now Liquid four times. My first review opened with this paragraph. “It's only fitting the FAST 601 is the first MPEG-2 system to undergo an in-depth review in Video Systems, as it is the first MPEG-2 system brought to market. Being first to market is always a mixed blessing. If the market is waiting eagerly for the new technology, being first is great. But when the market doesn't understand the new technology and so hasn't yet come to desire it, being first is problematic.”

So problematic, that by my third review I wrote, “Edition is the name Pinnacle has given to a version of purple -- which is the DV version of an NLE developed, several years ago, for blue. While blue was a work in progress from FAST of Germany, the NLE application developed for blue was shipped on FAST’s 601. (The 601 was a 50Mbps MPEG-2 NLE system that had the misfortune to be released at the height of DV-mania.)” Pinnacle had bought FAST and got 601, purple (the NLE software for the 601 and blue), and blue itself. Pinnacle named them Liquid. (Avid now owns Pinnacle Systems.)

It is ironic that years after FAST developed an MPEG-2 NLE, many of the other NLE suppliers are working feverishly to do the same. To date, this has meant simply hacking support for specific flavors of HDV. Had these companies developed an MPEG-2 engine that worked like a hardware codec -- as did FAST -- all the flavors of HDV would inherently have been supported.

Jumping back a few years, my second review covered Sony’s ill-fated ES-3 NLE. I began the review by saying, “The entire ES-3 is built for Sony by FAST of Germany. The software is identical to that on the FAST Silver (a.k.a. 601). Except for the InnoVision-designed CG, there are no pulldown menus. One either clicks on FAST-designed command icons (many of which you'll never have seen before) or right-clicks on an object to get a list of commands relevant to the object. Sounds neat, but often it is not. For example, after logging clips, I wanted to perform a batch-digitize. I could find no icon that 'looked like' it might do the job. Help told me to 'choose the command Batch Digitize from the Content area shortcut menu.' Duh! So I started right-clicking on every object and surface until I got the correct pop-up menu.”

Avid now refers to this GUI as Classic, and it is still available. For those purchasing Liquid today, the new GUI features a set of menus and is vastly easier to learn.

In my fourth review of Liquid, I described a powerful enhancement. I said, “Liquid Edition PRO significantly enhances the Edition rendering engine to support realtime preview.” As video frames were decompressed, the CPU rendered simple effects. Edition PRO shipped with a PCI card that contained analog I/O plus a GPU chip to co-render effects.

Pinnacle’s documentation (with the word Pinnacle replaced by the word Avid) now covers seven classes of effects: classic clip effects and classic transitions (none of which are realtime, but which can be background-rendered), CPU clip effects, CPU transition effects, GPU clip effects, GPU transition effects, and special effects. Special effects can use the CPU and/or GPU. (The GPU is no longer on a PCI card as the software uses your PC’s graphics processing unit.) The latter five effect classes have the potential to provide realtime previews, but also can be rendered in the background prior to export to tape. (The screenshots below show how I customized the Effect Racks for my editing needs.)

What makes Liquid’s effects set difficult to comprehend is that the same filter can be available in multiple classes. Unfortunately, these filters may, depending on their class, have slightly different names and available features, use different algorithms (thereby offering potentially different quality levels), and may preclude, should you use them, certain downstream workflows. For example, the powerful realtime Color Correction function does not support keyframes. If you need keyframes, you will need to use the far less capable CC.

In the next few installments, I will share what I learned about working with Liquid 7.1. I will also cover topics that emerged precisely because of Liquid’s many strengths.

For those who decide to use Liquid, I will provide the specifics of my HDV workflow. And, of course, I’ll let you know how the HDV and DV exports looked -- and how well DVD creation worked.

© 2009 Penton Media, Inc.