TECH TIPS
Captured!
And Why It's Better than Exporting QuickTime Files
by Scott Janush
This is a quick combination tutorial on how to capture QuickTime files for your sound and music departments using Final Cut Pro direct from your Avid editing system, as well as a little bit of information on watermarks and serial digital interface (SDI) video (http://en.wikipedia.org/wiki/ Serial_digital_interface).
I’m currently on my third production on which I have provided capture files for turnover, and I had every intention of doing the same on this project. In the past, I had used the AJA I/O box running component inputs and the Canopus ADVC-110 running S-Video inputs. I was going to use the Canopus on this project, but we received a request from our sound vendor to use the AJA Io LD with SDI video for a higher-quality capture than what the Canopus could provide using the S-Video inputs. All of the boxes interface to the computer using a single FireWire 400 cable.
Using the SDI outputs required little work on the Avid side, other than hooking a BNC coaxial cable from the SDI output of our Adrenaline break-out box to the AJA box and additional lines from the mixer (Mackie 1604 VLZ) to the audio input of my Apple G5 tower.
The AJA will embed audio along with the video in the SDI signal, but we chose to use the analog outputs of our mixer to provide on-the-fly flexibility when needed. We used the control room outputs, fed via the bus outputs, and sent this to the stereo analogue input on the G5.
Why Capture?
Why would you want to capture as opposed to exporting a QuickTime
file or turning over tapes? If you turn over tapes, there are the
obvious costs of tape stock as well as any additional dub costs if
those are required. In addition, there are security risks with sending
turnover tapes out for dubs.
By capturing playback on the fly, you can get an A-B reel out the door in less than 30 minutes, from pressing play to putting it in the hands of a courier on the way to a vendor. Using this method, you can capture versions for sound and music departments, each with a unique ID burned into the picture, in under one hour.
Exporting is a great way to go if you have the time. While I find there is a quality difference to be gained by export, the time needed to process the files is slower than capture. While this certainly works in an ideal world, I often find that we work in less than ideal circumstances, and thus require a faster turnaround––especially with finessing deliveries of last-minute visual effects. Plus, you are more likely to watch the sequence if it plays on a monitor, as opposed to just exporting in the background.
Given the scenario in which we provide tapes to our sound departments, they would take our tapes and capture their own QuickTime files. Capturing in editorial allows us to eliminate generation loss. I believe that the trade-off of time gained over exporting supercedes the slight quality gain that might be achieved via export.
Hardware Needed
The two solutions listed below are external stand-alone converters
that are FireWire-based. These are the easiest to implement––requiring
only a FireWire connection to the computer––as well as
being the most versatile for our purposes. In addition, these connections
are the only way to use a laptop or slotless computer for capture.
Canopus ADVC-110. This is a low-cost converter that handles analogue composite and S-Video signals, and is a definite bargain at its price point of $269. You will find large numbers of this box in use at facilities the world over, due to its tremendous value; in addition, it is NTSC and PAL compliant. It’s likely that your sound or music departments are already using a Canopus box for either capture or playback (www.canopus.com).
The AJA Io LD converter handles digital SDI signals. This box is considerably more expensive at $999, but does provide a significantly cleaner signal for capture via the SDI signal path (www.aja.com).
There are other PCI card-based solutions, at various cost points up and down the scale, but these are less flexible in terms of moving the capture configuration from one editing system to another––unless you plan on moving the capture CPU. For example, Black Magic has a PCI board for SDI conversion that is $295, but it would be tied to a specific CPU into which it is installed (www.blackmagic-design.com).
With respect to CPU power, I am currently using a dual 1.8 Ghz G5, since that is what I had around, but you could also use a G4 tower, of which there are many. At these data rates, any current CPU is able to cover the load without any problems whatsoever.
Software needed
In the past, many sound and music departments regularly used Adobe
Premiere in conjunction with an Aurora igniter card using a Motion
JPEG codec (www.auroravideosys.com).
Recently, additional hardware and software that allow more flexibility in terms of capture have come to market with lower price points. These would include Final Cut Pro and various converter boxes (www.apple.com).
 Figure 1. |
FCP Capture Template
Within Final Cut, create or modify a capture template to reflect your vendors’ individual needs. You will need to specify frame size, input source for audio and video, compressor (codec) quality and frame rate. And you have the option to limit data rate for playback. Ask your vendors for their specific requirements for their configurations. This is our template for our sound company (see Figure 1). The Digitizer and input are where we have selected the AJA Io LD as our image source.
Avid Settings
Nothing listed in this section is different from what you might do
for a digital cut, and is merely the method that I have found to work
well.
 Figure 2. |
Film Speed
The key to making this work is to have the Avid play the sequence
at video speed (23.976 fps) rather than film speed (24 fps). Since
post sound is usually performed at video speed, this mode will emulate
the playback speed chosen when doing a digital cut at 23.976 fps (see
Figure 2).
Watermarks and IDs
Like most people, I use the title tool to create burn-ins and IDs
for the Avid.
|
For this process, two additional picture tracks are needed. The lower of the two tracks is for a footage and timecode (TC) burn-in placed in the upper letterbox. This goes on the first track above your existing timeline. Depending on your source, this can play with either a luma or chroma key in real time, non-rendered.
In my case, I have multiple clips that contain various windows, depending on the vendor needs, ie, a DI house may want a frame count and TC, while sound may want footage and TC, and music may want TC only.
While it is possible to create a burn-in with every timebase known to man, as much as possible, I like to give people what they want without crowding their frame too much. You can create these in the Avid, using the TC FX plug, but they are not real-time tracks and that destroys the premise of a real-time capture. I create these in After Effects and bring them into the Avid as real-time keys, either luma or chroma, depending on the BG, and they will run in real time, with the ID track above it. The second, higher track is for the ID track.
The Avid provides the opportunity to set color and opacity on all titles. You can take advantage of that and lower the opacity on certain titles, essentially creating a watermark that will appear to be embossed over sections of the image, while still allowing sufficient visibility to work unimpeded. I create a minimum of three titles in one graphic.
Title one is placed within the image at the top of the frame with the “property of” banner. Title two is placed at the bottom of the image with the version ID information. The third title is placed in the center of the image with the ID of the person or vendor receiving the file or tape. I size this title as large as possible until the point of pain is unacceptable to the vendor. You can generally get away with more blockage to the music department. Keep in mind that everyone’s concept of unacceptable is different.
|
All three titles are created at 100 percent opacity with drop shadows. The large central ID title is the one you want to turn into a watermark. In order to do this, select the title with the arrow tool, select the fill, shadow and border colors, then click and hold on one of the transparency boxes to the right of the color boxes. While holding on this box, lower the opacity until you have a look that you think is acceptable. To the left is more opaque and to the right is more transparent. Typically, I fall in the 80-90 percent range for the fill and shadow. Salt and pepper to your own taste.
The good-looking cat in the photo is named Baskin (see Figure 3) and I’m pretty certain that he does not want to find a pirated copy of himself being sold in Times Square before the release of his feature debut. A distinctive watermark spelling out “Editors Guild” in large letters may make it less likely to happen.
The secure aspect of a watermark of this size makes it far more difficult for anyone attempting to pirate the sequence––unless they intend to darken the image so much that it is unrecognizable, or they intend to cover up the text block, obliterating the name (see Figure 3).
|
Avid Timeline
Since we are capturing wild, without the benefit of deck control,
we will get multiple frames of whatever is on the output of the Avid
at the start of the capture process.
To eliminate this, add filler to the start of your sequence in the
timeline. The capture will only have frames of black, and then will
have a clean picture start once the sequence gets rolling (see Figure
4).
Once all of your tracks are in place, render all tracks below the top two. This will prevent the titles from going non-real-tim and having a drop-out. Back the cursor up to the head of the sequence, hit the capture button in FCP and press play on the Avid. When the sequence is finished, press Escape to stop the capture process in FCP. If you captured to your shuttle drive, you are ready to go. If you want to be nice to your sound and music people, you can do the following to make their day go a bit easier.
Using QuickTime Pro, it is possible to trim a QuickTime file, leaving only the selection you want. To eliminate the recipient from having to find the actual first frame of the head leader, open the capture file in QuickTime Pro. You should see two little brackets surrounding the playback cursor. Move the right bracket until it is on the last frame, prior to the leader or picture start. Using Command-X, delete the frames between the start of the QuickTime file and the frame before the location of your bracket. You can also hit Command-X repeatedly, which will delete the frame being displayed. Once you are on the picture start frame, close the file and save. Instant trim!
Hand the media to your courier and hopefully you are out the door just a little bit earlier.
Scott Janush is currently working as the First Assistant Editor on Shoot ‘Em Up for New Line Cinema. He will provide template files related to this article for those who are interested and can be contacted at scott_janush@ yahoo.com.
[ return to top ]