Look at the many steps that footage typically goes through before getting to air or distribution.

And these steps are often further sub-divided or expanded. 

For example, portions of the video during the editing might be sent off to the graphics department for added effects work — with the resultant composited footage then brought back into the editing.

And after a program is finally edited, the sound is often stripped off and sent to an audio mixing facility for “sweetening.”  Then that new mix is brought back into the edit system and conformed to the picture before the program is laid off to the edited master tape.

You might ask, does maintaining unity gain really matter in this digital age?  You might be thinking, what with all the computers being used throughout, can’t one just adjust levels digitally as needed at any point along the way?

The problem with that thinking is that making radical adjustments at any stage in the pathway can introduce “noise” in either the video or audio.  Plus, you can correct only so far. 

Here is an everyday example of what I am talking about.  You may have tested the limits yourself when working on an underexposed digital photo in Photoshop or similar graphic program.  Sure, the computer software allows you a lot of correction ability that was unimaginable just a few years ago.  But chances are, if the photo is seriously underexposed or “out of whack” color-wise, you will be limited as to how much correction you can apply.  Despite your best efforts, chances are you will not be able to get the image to look very good.

Now, let’s look again at the production/post-production path chart – and think of every step as a point where the picture “gets taken” by your camera – an opportunity to affect the signal . . .
 
See the importance of maintaining consistency – or unity gain?

And the same goes for audio.

So how does one maintain consistency throughout the production and post-production chain?  How do we know what the intended or proper Picture and Audio levels are at any point in the production/post production process?   How do we know what is real?

The two basic metrics used to confirm proper levels are SMPTE (Society of Motion Picture and Television Engineers) bars for video, and 1K hertz tone for audio.  Check out this link for more details on those: http://tinyurl.com/59xckj

That is why it is standard procedure to lay down at least 30-secs of bars and tone at the beginning of every tape shot in the field and on every edit master and subsequent dub master.  Bars & Tone provide an industry reference.  When you release your videotape for broadcast or duplication, the 30 seconds of Bars & Tone at the beginning of your tape insures all of your hard work will be reproduced accurately.

For those dealing directly with the technical aspects of production and post-production, there are other intricacies to keep in mind when calibrating equipment in the signal path to bars and tone.  For video, there is component video http://tinyurl.com/pgvyh, SDI (serial digital interface) http://tinyurl.com/2u4wvp and of course the burgeoning High Definition field http://tinyurl.com/6c7d8j  &  http://tinyurl.com/5s6y8h

Also, remember to check the calibration of your “reference set-up equipment.”  About once a month check the calibration of your color monitor, waveform/Vector scope and the Audio Meter.

For audio there is the variable of whether the meter you are using is a VU (volume units) or PPM (Peak Program Meter).  Read more about that here: http://tinyurl.com/6xzp3d

And there is also the realm of digital audio to consider.  Formats such as AES http://tinyurl.com/676et3  and Dolby 5.1 “surround sound” http://tinyurl.com/onwte

One last note about audio meters and tone.  If the audio meter is “summed Mono” (Left & Right channels combined), the meter will read 3 dB hot when playing tone on both audio channels at the same time.  Always play the audio channels one at a time to confirm proper Tone level on a “Mono Meter”.

Suffice it to say that unity gain is important to always keep in mind whether you work in a large production facility or an indie production boutique.  Almost every broadcast and cable network insists on a strict quality control review of programs being considered for air.

If unity gain has not been carefully maintained throughout the production control, I can almost guarantee you that issues will arise that will result in the program being rejected.  And as a producer or technician, that is something you do not want to hear.

So, avoid that frustration (and added expense).  Watch your levels closely throughout the production and post-production process.  Insist on unity gain throughout.

Your comments are encouraged below.

Feel free to contact Chris Vazquez at chris.designsmith@verizon.net or 301-953-1427.

Other articles you might be interested in:

Is there generation loss in digibeta?  Check out Chris’ article: http://tinyurl.com/6yd6gn

Curious about setting up your editing timeline correctly?  Check out David’s blog: http://tinyurl.com/5mbl8u

Need CD, DVD or tape duplication?  Contact David Ryan at dryan@videolabs.net or 301-217-0000 x104

OLED displays are based on the organic process of “electro phosphorescence”. Think of Fireflies, plankton, and many sea creatures, they all have the ability to produce organic light.

OLED panels are based on electro phosphorescence research.  The panels use electrical current to stimulate organic materials (typically polymers) to produce red, green, blue, and white light. They do not require a backlight, use a third the power, have a wide viewing angle, have a contrast ratio of 1,000,000:1, can produce 16 million colors, and refresh at 200 times per second for extremely smooth motion. However, like most emerging technologies, OLEDs have a lot of advantages and a few disadvantages.

OLED Technology… OLED displays contain several thin layers stacked up to allow “electrical current” to flow through the layers. Based on the attraction of positively and negatively charged particles, current flows from the “Cathode Layer”, through the organic material, to the transparent “Anode Layer”.  As current flows between the cathode and anode the mid-layer organic material is stimulated to produce visible light.  The color of the light is dependent on the type of organic material placed between the cathode and anode. OLED panel layers are laminated on a substrate of clear plastic, glass, or foil. The layers vary depending on the intended function of the panel, but the basic structure contains the following layers.

- Substrate: Provides a base for the display (clear plastic, glass, or foil)

- Anode: Removes electrons when the current flows

- Conductive Organic Layer: Creates the electron “holes” when current is applied

- Emissive Organic Layer (creates light): Transports electrons from the cathode

- Cathode: Injects electrons when the current (electricity) flows

A Passive or Active matrix is used to control how and when the OLED display produces light. Passive-matrix OLED (PMOLED) panels use strips of anodes and strips of cathodes off-set by 90 degrees to create an X-Y grid. The intersections of the strips create the pixels where the light is emitted. Energizing selected strips determines which pixels turn on and which ones remain off. PMOLED displays are inexpensive to produce, but limited to small screens (2 to 3 inch diagonal). Passive displays are best suited for text and icons, and are found in cell phones, PDAs, and automotive dash boards.

Active-matrix OLED (AMOLED) panels use a “thin film transistor” (TFT) array to form a control matrix. The TFT array contains the circuitry to turn on the required pixels to form an image. AMOLED’s are used for large screen video displays.

OLED Pros and Cons… Some of the advantages of the OLED for HDTV displays; extremely fast refresh rate for smooth motion, no back-light required, ultra thin panels (3 – 10 millimeters), flexible substrate for roll-up displays, transparent displays as depicted in the film “Minority Report”, 170 degree viewing angle. The disadvantages are they’re expensive to manufacture, have only a 10,000 hour (3 year) life span for the blue organic layer, the OLED matrix is easily damaged by water and requires a method of moisture sealing to protect the display.

Future Applications… One of the more interesting applications of the OLED technology is in room lighting. White OLED panels emit light that is brighter and more energy efficient then fluorescent lights. White panels can be produced in a variety of color temperatures.Other OLED suggestions include foldable electronic newspapers, wall-size television monitors, and heads-up instrumentation for aircraft and automotive windshields.

For additional information take a look at the following links…

CES 2007 video report on OLED TVs http://www.youtube.com/watch?v=5rMFZ4O_oLs

Sony’s 11″ OLED panel ($2,500) http://www.sonystyle.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10551&storeId=10151&identifier=S_BrandShowcase_OLED&SR=sensory:shop:oled:ss&ref=http%3A//www.sony.com/index.php

OLED-TV Display/Monitor Technology News  http://www.oled-display.net/oled-television

Watch for more about video engineering with Chris here on DavidRyanMediaSolutions.com

Chris Vazquez can be contacted at chris.designsmith@verizon.net or 301.953.1427

And don’t forget, for all your media replication needs (CDs, DVDs & videotape) contact David Ryan at dryan@videolabs.net 301-217-0000 x104   Y hablo espanol.

Re-recording the Timecode… Most professional video tape recorders have had the ability to insert new time code. Typically the longitinudinal TC track was accessed via insert edit function and restriped with the desired timecode. All DV formats have timecode recorded in the allocated digital data sectors. The Sony HVR-1500 deck has the ability to perform a “timecode insert” on an existing DVCAM recording. The procedures for the TC insert are listed on pages 68-69 of the HVR-1500 operations manual. The link to download a copy of the manual is provided at the end of this article. Unfortunately, the TC insert feature is not currently available for the HDV format.

Timecode Regeneration – Avoiding Problems… If your DV camera or VCR has only basic TC control settings, each new tape will start at 00:00:00:00. To ensure continuous TC the “regen” option must be turned on. Typically, this requires adjusting a switch, or activating a menu function on the camera. With the TC generator set to “regen”, previously recorded video must be played for a moment to allow the TC generator to read the existing TC on the tape. When the TC generator sees the existing TC, it locks to the playback TC (jam-syncs) and generates new matching timecode. The camcorder must perform a back-space edit to allow the TC generator to see the last second of the existing TC before switching to record for the new video. Although uncommon, some camcorders provide a menu setting to de-active the “back-space” function. If the back-space function is off, a break in the TC may be created every time the recording is stopped.

Check the TC Number Display… If TC regen is working properly the TC display should change from 00:00:00:00 to a new running time code when playing an existing recording. If your back-space function is not working try manually cueing the tape to the desired edit point, with tape in pause press the record/play buttons. In essence we want a series of clean assemble edits, with internal regen timecode to avoid discontinuous timecode problems.For additional information take a look at the following links…

Sony HVR-1500 Operation Manual, pages 51-54 & 68-69 http://www.visionaryforces.com/downloads/Sony_HDV-1500_HD_VTR_Operating_Instructions.pdf

Sony HVR-Z1U guide, pages 76-77 http://bssc.sel.sony.com/BroadcastandBusiness/docs/manuals/hvr-z1u.pdf

Feel free to share any questions or thoughts you may have in the comments below.

Watch for more about video engineering with Chris here on DavidRyanMediaSolutions.com

Chris Vazquez can be contacted at chris.designsmith@verizon.net or 301.953.1427

Processing Video… The Digital Betacam VCR processes video using the following parameters; color sampling at a rate of 4:2:2, a maximum data rate of 90 Mbps, 10 bits per sample, and a compression ratio of 2:1.

Compression of the video signal, by its very nature creates some loss of information. The compression software (algorithm) is tasked with evaluating the video frames for similarities. As similarities are identified, the video data can be recorded for the first frame with a flag to re-use the data for the next video frames. When a change in the picture content is detected, the process starts over.

Loss of Picture Information… For instance, if our picture has a blue sky that “basically” doesn’t change for 30 frames, we can record the blue sky data for frame 1 and re-use the data when playing back frames 2 to 30. This provides a significant reduction in the amount of data to record on the tape.

If our original blue sky contains slight differences in color, we may lose some of the blue shading during the compression process. Satisfying the compression ratio may require compromising on the picture detail. This is why video processed at a high compression ratio tends to lack detail.

The DigiBeta format has been successful because it has a low compression ratio and is very efficient in recording and playing back the video signal.

File Transfer… At the beginning of the article I mentioned it was possible to avoid generational loss if you could make an exact copy of the digital file recorded on the tape. On the rear of some of the current generation professional VCR’s there is a BNC connector labeled “SDTI” – Serial Data Transport Interface. The SDTI connector “allows for lossless transfer of data to other devices which have the same codec”. Since this is a “file transfer”, the video can also be dubbed faster than real time.

For additional information take a look at the following links…
Compression in Digital VTRs – http://pro.jvc.com/pro/d9/ARTICLES/WATKINSON.htm
What is SDTI? – http://www.digitalpostproduction.com/Htm/Tutorials/WhatIsSDTI.htm

Watch for more about video engineering with Chris here on DavidRyanMediaSolutions.com

Chris Vazquez can be contacted at chris.designsmith@verizon.net or 301.953.1427

SD Pixels… In video we have high definition devices (HD) with a native 16:9 format and standard definition devices (SD) using a 4:3 format. When recording on an SD format like DV tape or DVD disks, we are limited to a 4:3 rectangle of 720 x 480 pixels (480 viewable scan lines).

If you’re shooting on DV tape and the camera has ability to record in “anamorphic mode” the result will be an intentional horizontally squished image. This process will fill all of the available SD pixels when displayed on a widescreen picture image.

Viewing a corrected image from the camera or DV deck… If your SD 4:3 video monitor has a 4:3/16:9 button, you can view a corrected widescreen image by selecting 16:9. The image will appear letterboxed. You can also accomplish the same effect by adjusting the vertical height on most monitors.

Editing… During the edit process the anamorphic DV footage stays in its original form – squished. Some edit software can “display” a proper widescreen image on the computer monitor during the editing process without rendering.

Encoding an Anamorphic master to DVD… Within the DVD encoding standard is a provision (flag) to identify the disk has anamorphic program material. When the disk is played, the DVD player and the widescreen DTV will recognize the anamorphic signal if the menu settings are in the correct mode.

In conclusion, anamorphic enhancement is a tool that allows us to use existing standard definition video equipment to record and display a widescreen image at the best resolution possible.

For additional information take a look at the following links…
Final Cut Pro – http://docs.info.apple.com/article.html?artnum=75079
The Ultimate Guide to AW DVD – http://www.thedigitalbits.com/articles/anamorphic/
World’s Easiest Explanation of AW – http://gregl.net/videophile/anamorphic.htm

Watch for more about video engineering with Chris here on
DavidRyanMediaSolutions.com

Chris Vazquez can be contacted at chris.designsmith@verizon.net or 301.953.1427