Highdef Pre and Post Production
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When any new technology is introduced, a new way of thinking is often necessary to make it work properly. This has proven to be true with Highdef production. What this ultimately means is that preparation is critical to guarantee success. And with preparation comes the need of knowledge, a clear understanding of the technology from acquisition through post and distribution. Equally important is the attitude of an open mind, not assuming anything from past experiences in other formats.
Before starting a Highdef project, there are certain elements of the process that need careful consideration. One perspective that seems to be quite relevant is to look at the project from the end to the beginning. In other words, start with post production and distribution, then move backwards to acquisition. The following list of considerations will help to illuminate the HD production process, and should be factored into any acquisition format decision.
Film out and deliverables
If the project will be released in theaters, it is likely you will need to transfer your finished HD edit to 35mm film at the end of the production process. If this is the case, for Highdef, it will be best to shoot your project in 24P, the progressive-scan format that mirrors film frame by frame. If you want your project to look like film even if it will only be shown on television or digitally projected, then it's also best to use 24P as your origination format. If you want the final product to look real, as if you are there, living it live, then the 1080i/60 ("1080i") format will serve you best. This is the format that most documentaries use to make the viewer feel like he or she is "there." For example, projects about sharks will seem more "real" in this format. If you use 1080i for a dramatic project, it will have a "soap opera" look because of the feel of the format, and you will be forced to add a "film look" later in the process if you want to eliminate that effect.
Color Correction/Digital Intermediates
Before shooting, it is best to be clear on the color treatment your project is going to have. If you want to create a special look, it's best to have an in depth discussion early how that will be accomplished all the way through distribution deliverables.
Color Correction in HD has nearly infinite possibilities today, especially if the original footage has been shot fairly straightforward, without too much filtration, without crushing the blacks, or over exposure. Blacks can always be crushed in the final product if that is what is wanted, but if they are crushed at the beginning, there is almost nothing you can do to change that later. The same is true for over exposure. Unlike film negative, HD has nothing to work with if over exposed. On the other hand, underexposed HD often has enormous flexibility to recover imagery. This flexibility has created the concept of Digital Intermediates. Projects like "Oh Brother Where Art Thou" had an amazing look: all created after the shoot. By transferring the film to HD and then manipulating the color, contrast, gamma, brightness, etc., the end product was very stylized to match the subject matter. After the changes are made, the digital master created is the Digital Intermediate. From this master, all subsequent copies are made in film, DVD and video.
It is also possible to create the look on the set through filtration and "painting" the image in the camera. For example, the look of the movie "Once Upon a Time in Mexico" was created mostly in the camera. Creating the image on the set is a wonderful time saver later, but you need to be sure that's the look you want, because it will be nearly impossible to change later. Because the images can be controlled while filming with high quality monitors, and HD is "what you see is what you get (WYSIWYG)," you have enormous control on set.
Color correction can be done in several ways. Probably the best is with a system like DaVinci's 2K color corrector. With power windows and other features, maximum flexibility is achieved. Skies can be changed from gray to blue or vice versa. Colors can be muted or emphasized, and overall corrections can create a "period piece" look. Sony also provides a very flexible color correction system in their switchers, and non-linear systems are now offering similar capabilities.
It's important to understand how long it will take to do the color correction you want. Sometimes it can be done in a few hours for a feature if all you're doing is correcting a few camera and lighting changes. Other times, it can take a week or more of work depending on the complexity. A discussion with a colorist before the shoot is worth the time.
If the project is destined for transfer to 35mm film, most of the color timing will be done digitally prior to the transfer. Sometimes additional film effects can be created such as a chemical bleach bypass process on the final master. Obviously, it's good to do tests to see if you will be getting the image you want.
It should be noted that color correction in post is limited by the bandwidth reduction techniques used by the recording medium. Timing your look in the camera gives you a more defined color palette to create your look and increases the capability to make more subtle adjustments in post. But, it can also reduce your ability to make drastic changes in color later. In some ways timing in camera is similar to picking a certain film stock for its color signature.
In the next few years, all projects will probably go through the Digital Intermediate process because of the incredible flexibility and reliability. Knowing how you will handle the color correction early will help immeasurably when you're filming.
One of the biggest mistakes made in Highdef production is the lack of planning for post production. And these mistakes can be costly in both money and time. For that reason, it's important to have a clear idea of your post production pathway. It's not enough to say that you'll use a non-linear system or a traditional online bay without examining both processes in detail with your specific project's requirements in mind.
The first consideration in post production is the downconversion format you'll be using. A downconvert is conversion from an HD format to an NTSC (standard definition) tape format with embedded (and possibly visual) time code, usually in a format that you have easy access to for inputting into your non-linear editing system. If the project is 24P, downconverting also changes the video from 23.98 fps to 59.94 interlace (insertion of a 3:2 sequence) and properly converts timecode from 24 frame to 30 frame.
The most common formats for downconversion are Digital Betacam, DVCam and DVCPro (DV or MiniDV are not recommended because of difficulty in producing embedded timecode that corresponds with the field tapes). These formats all have timecode capability, high quality digital imagery, and digital audio. These features make them ideal for inputting into an Avid, Final Cut Pro or whatever system you're using. Because your audio stays digital, it's likely that you'll be able to use the audio files you create when editing all the way through to the final audio mix. Less desirable formats include 3/4" or Beta SP. These have analog sound tracks, and picture quality is not as good as the digital formats. Some productions have begun to use products like the Evertz Afterburner or Miranda MDC-800 to perform downconversions directly on the set. Some have gone as far as inputting signals directly into an editing system on the set. This can allow for a shot to viewed in context of other shots that have already been completed.
The most important function of downconversion is proper handling of timecode from the HD field tapes. The Edit Decision List (EDL) that you take to the HD online session must have time code that relates directly to your field tapes so it is very important that the process is done correctly. You don't want to get all the way through the post process and find that the downconversion timecode was not handled properly. This can take a lot of time and money to fix.
If you have a 24P project where some tapes will be shot overcranked(slow motion) or undercranked(hyper motion), you need to take a couple of extra steps. First, these field tapes should always be shot on separate tapes from regular speed material. This is done because both the Panasonic and Sony systems do not automatically play back the images at slow motion, so all off-speed shots will need to be converted. For the Sony system of slow motion, create separate field tapes for every slow motion speed. The Panasonic system requires a Frame Rate Converter (FRC) which recognizes the different speeds set in the camera so mixed speeds can be rendered on the same tape. The Sony system uses frame interpolating hardware or software, and each speed is treated differently. Tapes shot for slow motion need to be copied to another HD tape at the desired slow motion speed. Then this new "effects" tape will need to be downconverted to the desired format for inclusion in the offline process.
Offlining for HD
With the current status of post production, it is recommended that non-linear offline editing for both 24P and 1080i projects be done in the NTSC video format. This allows for huge cost savings as creative and content decisions can be done on much less expensive editing equipment. The first step is to take the downconverts and digitize them into your non-linear edit system (NLE). Ideally all of your field tapes will have reel numbers in the hour part of the time code. This will separate them from each other easily in the list. In addition, care must be taken in the inputting process in the NLE to make sure that reel names are delineated properly. The most important of these steps is to designate 6 character alphanumeric reel names when digitizing (keeping it to only 4 characters is even better). If you fail to use proper reel names, you may encounter severe difficulties in on-line because many online editing systems only recognize the first 6 characters. So if you name your camera reels "MYREELS_001, MYREELS_002, etc.", when you get to online, all your reels will be listed as "MYREEL."
For 24P production, offline editing can be done as either a 24 frame or standard 30 frame project. If you keep your project standard 30 frame, the EDL can be converted from 30 frame to 24 frame at the start of the online process. This allows for any video editing system that supports timecode input and EDL export to be used for offline 24P production.
When doing 24 frame offline, generally you should not use any speed effects generated by the offline system in the EDL. They may look OK in the offline, but not work at all in 24P online. On the other hand, they may sometimes work, but you will want to see the final effect in 24P to make sure you want to use it. For that reason, it's probably better to create the off-speed effect in HD 24P first, then downconvert the result and put it in the list.
CGI, VFX, Slo-Mo
If your project has a lot of visual effects (VFX) work, you may want to use a format that has higher resolution per frame than standard HD. That is why George Lucas is now shooting Star Wars with Sony's new SR HDCAM format. His artists will have more color information per pixel to deal with and manipulate. However, if you don't have George's budget, you may want to avoid the new formats until they have clear post production pathways that are proven. The standard HDCAM format has proven to be very viable here too. 720P works well for television output, but some artists don't feel it has enough detail for theatrical output for graphics because of the 1280x720 pixels that it provides. Having said all this, it must be remembered that each project is different and there is no way to generalize the best system for specific needs. The camera acquisition portion of visual effects shots are usually converted from the HD tape into computer files as individual frames. These can then be manipulated by any number of processes and systems to create the effect that is appropriate for the project. Once the frames are completed, they can be transferred back to a "VFX tape" and downconversions made to intercut the VFX shots with the offline.
Because it is so easy to import graphics, animations or other CGI (Computer Generated Imagery) into non-linear systems, it can sometimes be problematic when it comes time to online. The quality of the imagery that looks good in offline may not be adequate for HD. Also, moves, and other effects created in the offline process on graphics will often not work in online. For still graphics, it's best to create them in the resolution of the final HD format. This will either be 1280(H)x720(V) or 1920(H)x1080(V). You can bring these files to the online session for integration into the assembled show, or use the following process. For animations and other CGI, treat them like they are a separate entity just like another field tape. Render them out to frames and have them transferred to an HD tape. Preview the animations in HD to make sure that they look right. Animations can fool you if you have only seen them on computer screens. Then, just like field tapes, downconvert the "CGI tape" and include it as a reel element in the EDL.
If your 24P project has a lot of slow motion effects, you have several choices. The first is Panasonic's Varicam which is able to capture between from 4 to 60 progressive frames per second at 1280 (H) x 720(V) resolution. These pictures are recorded to a DVCProHD tape. Through the use of a frame rate converter (FRC) or an NLE with Varicam support, you can extract these frames to reveal the various slow/fast motion looks. This has the best comparison with "overcranking" and "undercranking" used in film. If you need extremely high frame rates (above 60fps), it is probably best to shoot in film and transfer to HD. The second HD slow motion alternative is with Sony's HDCAM 1920 x 1080 format. Using various techniques, post production houses can extract motion information from specially shot HDCam tapes to produce slow motion. For the best results, shoot for slow motion on HDCam using the following table:
Desired Slow-Mo Speed
Equivalent speed for film shoots
Set HDCam Camcorder to this frame rate.
Make sure that you shoot different slow-mo speeds on different tapes and let your post house know which tapes are at which speeds so that the conversion will be done properly. Other frame rates can be created using the Sony system, but occasionally some pictures will not convert well. Specifically if lateral motion is extreme in the frame, then the motion blur between successive fields will make it difficult to create clean progressive frames. The engineers are hard at work to find new alternatives, but this is what is available now.
The best way to determine which format or solution will be best for your FX, CG or off-speed effects, is by testing prior to shooting. Camera rental companies and post houses will usually cooperate with tests if you promise to bring the final job to them.
Titling or Character Generation (CG) in HD has some unique issues as well. You should view credits at HD resolution, but also make sure that you preview them in any other format that you will be delivering as well. A title that looks good on a large, clear HD monitor may be unreadable or partly off the screen on an edge cropped VHS. This may affect the size of the titling and the font choices, especially for thin fonts. Previewing in the distribution formats is the key and will save much grief later.
If titles are created as graphics before the online session, it's important that their size is exact. If a title or graphic is rendered and then blown up to accommodate a size change in a DVE, you will lose resolution and may make the titling unacceptable. It becomes essential to determine size, placement, and other attibutes early in post production prior to the final online, and preview them as soon as you can in both HD and SD outputs.
For 24P projects, the critical titling mistake is expecting a credit roll to fit into a specified length of time. Because of the low frame rate, rolling credits need to run very slowly so that they do not appear jerky. It is best to prepare your credit roll before the audio mix is complete so that the timing can be correct.
If you're doing your preparation for titling in word processing software before online, you'll save time and money. Templates are available from some edit facilities that facilitate this process. Conforming your titles to these templates will make it easier for the editor to input your titling into the online systems titling tool. For example, the Chyron DuetHD works very well with Microsoft Word file inputs. By putting in tabs and certain formatting instructions in Word, the DuetHD will be able to import long credit rolls and make formatting quick and easy. Fonts can be chosen at the time of the online session, but if you have a specific font in mind, check with the facility to see if they have it available. If they don't, you can usually bring them to the online session as true-type fonts for use in titling. Remember to give them the whole font on a disk for input into their system.
Prepare your list for Online
Once the offline is complete, the EDL needs to be exported from the offline NLE.
Here is some information for editing on an Avid system in preparation for a linear online. Other NLE's (Final Cut Pro, Premier Pro, etc) will have similar steps:
- Make sure that your reel names are 6 characters or less. If you fail to use proper reel names, you may encounter severe difficulties in on-line!
- Make notes in the EDL describing any effects, transitions, color treatments or anything that would be of use in the online session. The EDL format does not transfer information such as flips or picture in picture and these must be manually entered in the online suite but will carry notes to describe these events.
- Make a Digital Cut of your entire program (or of each film reel if
- Use the EDL Manager to output your final EDL(s). Each video track must have its own EDL, and only one EDL needs to have the audio tracks. To output an Edit Decision List (EDL) for use in a linear bay, you should insure that the following choices are made on the Avid. Use CMX B-Roll indication, A-Mode EDL on a DOS disk with clip names and no black events. Here's how to accomplish this on an Avid:
"CMX 3600" should be chosen under the FORMAT pull down menu. "A (Record In)" should be chosen for SORT MODE. Under DUPE LIST, select the "Multiple (B-Rolls)" option, with STARTING EVENT set to "1", then click OK. Under OPTIMIZATION, select "Optimize EDL". Make all other selections as shown below. We've compiled this Avid screen shot to help with your selections:
The EDL should be saved on removable media. When saving your edit list, use the DOS syntax of 8 alphanumeric characters without spaces followed by ".EDL". The following are valid names; TEST.EDL, VER6a.EDL, SAM39581.EDL and 2304.EDL.
- You should always bring a copy of your final sequence in a bin to your online session. The online facility then has the option of putting the list into one of their Avids to fix any problems.
Edit controllers can re-sort your list in any order desired. For this reason, it's best to receive a list that is sorted A-Mode. If you must pre-sort your list in a different manner, simply output multiple lists, with at least one sorted A-Mode, as outlined above. In addition, most facilities makes extensive use of advanced EDL tools, such as EDL Xpress and Pre!Reader to optimize your list for the fastest possible assembly time. Contact your editor for more information about auto-assembly options.
Send your EDL to the online facility a couple of days before the online edit. This will allow time for checking the list in advance and allow for any fixes to be made. Every system has its own quirks about EDL's. It's best to identify and resolve these issues before your session. It is often a good idea to also send a copy of the program (picture and sound) from the offline system as well. This can allow for scratch audio and video to be prepared for assistance in the online session.
Before you head to the online facility check that you have the following:
|VFX Reels, CGI Reels, Slow-mo Reels|
|Any still graphic element files|
|The completed EDL(s)|
|An output (Digital Cut) for reference checking and scratch audio.|
|Titling information in the proper format (including Font files if needed)|
Your show will be assembled according to the timecode information in the EDL. If you are having audio done separately, it is possible to reduce the amount of time spent in online if you do not have audio assembled in the online suite. The rough cut of the audio from the Digital Cut may be used as scratch track audio in these cases.
Because most projects end up on DVD today, and because DVD requires very high quality control standards, it is extremely important that your online facility has the best in monitoring, both visually and electronically. High quality HD scopes are essential. The HD monitor needs to be calibrated properly so you know what you're getting is exactly what the viewer will see. In addition, it's a good idea to see what the image will look like in NTSC video as you assemble the program. Just because it looks good in HD doesn't necessarily mean it will look good when it is downconverted.
If you can discuss your EDL with the online editor ahead of time, do it. Often an experienced online editor can point out problems that should be corrected before you go into online.
Preparation is the key. Knowing your EDL, FX, titling, graphics and color correction intimately ahead of time will save you money. Online assembly of an HD program should be a simple process. It will be if you come prepared.