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MillimeterHDV@Work
May 23, 2005 9:47 AM
The State of Editing HDV
Steve Mullen
As you made your away around the nonlinear editor booths at NAB, it’s very likely you were presented with marketing messages that promoted each company's ideal way of editing HDV.
The four techniques include draft, proxy, native, and digital intermediate. Let’s work our way through all these options. The use of FireWire and MiniDV tape makes it easy for folks to think of HDV as simply high-definition DV. There are, however, significant differences that make HDV editing very different from DV editing. There are three crucial differences. First, HDV uses inter-frame compression, while DV does not. Second, HDV audio is MPEG-1 Layer 2, not PCM. And third, the number of pixels is either 2.7X (1280x720) or 4.5X (1440x1080) the number of pixels employed by DV.
All these differences lead to the need for a huge amount of computation to accomplish editing. This need can be satisfied in several ways. One alternative breaks the task into less computationally intensive steps, which is the approach used by the draft, proxy, and digital intermediate solutions.
The other alternative, editing native HDV, performs all the computations while you are working with the timeline. As you might expect, to obtain good timeline performance, a very powerful computer is required.
We are all likely familiar with using draft editing techniques. We batch-capture a tape using a codec different from the one used by our camcorder. Naturally, this codec is chosen because it can decode faster than our tape’s codec. Apple’s PhotoJPEG can be decoded faster than DV, so it has long been used as non-NTSC/PAL draft codec for DV.
After the production has been edited, the timecode of the draft clips is used to generate a batch-recapture of the HDV material. Of course, this requires HDV equipment with frame-accurate capture ability.
Currently there is now only one proxy solution—DVgate Plus from the Sony Pictures division. It is available only with Sony VAIO computers. DVgate captures the entire HDV tape into clips. Because HDV is only MPEG-2, it is a simple task to play and trim HDV source clips. However, once you drop a trimmed clip into the timeline, a background transcode from HDV to proxy is performed on the clip. The transcoded clip is called a temporary proxy clip.
By splitting the pre-editing process into two phases, the amount of computing power required is significantly reduced - to the point where a fast 3.0GHz P4 or a dual 2.0GHz G5 can handle the task. The key to splitting the computational tasks is to first capture and convert HDV to an intermediate codec—and then edit this more efficient intermediate codec.
iMovie HD and Final Cut Express HD capture to the Apple Intermediate Codec (AIC). Unfortunately, AIC is not considered a very high-quality intermediate codec. In the Windows XP world there two manufacturers of digital intermediate formats: CineForm and Canopus.
All CineForm versions employ an intermediate codec called Carlsberg (CFHD). The CFHD codec is based on wavelet compression. CineForm empathizes that CFHD was designed to be a very high-quality Intermediate codec operating in a 4:2:2 color space. Quality is high because low-data-rate HDV MPEG-2 is decoded and then recompressed to a high-data-rate (80Mbps) codec.
Canopus has its own intermediate codec called “HQ.” Canopus believes that by using an intermediate that does not degrade either HDCAM or DVCPRO HD yet requires vastly less bandwidth than using 10-bit uncompressed, it has developed the optimal solution for editing HD and HDV. (Canopus also supports native HDV editing for those with dual 3.4GHz Xeon computers.)
All the current capture solutions transfer HDV via i.LINK. However, an alternative is to allow an HDV device to decode the 720p or 1080i video to analog component HD video. See my story "From Camera to Edit Suite" in December 2004 Video Systems for the full explanation. Below is an abbreviated treatment.
HDCAM and DVCPRO HD VTRs output HD-SDI (SMPTE 292M). A tiny HD10A converter from AJA Video Systems accepts YPbPr analog via three BNC jacks. The HD10A digitizes the analog input and then converts it to a bit stream that is available on three BNC HD-SDI output jacks. Next, you connect the HD10A’s BNC output to a Kona HD, Kona HD 2, or Blackmagic Pro PCI board’s input BNC using a high-quality 75-ohm coax cable.
Upon HD input, the uncompressed digital video can be stored to disk using Apple’s uncompressed 8-bit and 10-bit. A RAID is required because, for example, 1080i video requires a data transfer data rate of 124MB per second. Additionally, the Blackmagic and Kona 2 HD boards have the option of compressing using the DVCPRO HD codec. Now this compressed HD video can be stored to disk.
Windows-based NLEs that can directly capture and edit a Transport Stream include Avid Xpress Pro HD, Canopus Edius 3.3, Pinnacle Liquid Edition 6, and MPEG Edit Studio Pro. Both Apple’s FCP 5 and Avid’s Xpress Pro HD are also able to edit native HDV. The level of realtime supported is directly proportional to compute power.
Before the timeline can be recorded to an HDV camcorder or deck, the PCM audio must be encoded into an MPEG-1 Layer 2 Elementary Stream. This stream and the MPEG-2 Elementary Stream must then be re-packetized to a Transport Stream.
Sony unveils new CMOS-based HDV camcorder
Sony is expanding its lineup of HDV products for professionals with the new HVR-A1U model, based on a 1/3-in., 3-megapixel Complementary Metal Oxide Semiconductor (CMOS) imager.
Sony has improved upon the key attributes of traditional CMOS sensors with proprietary technology, and this innovative CMOS device is also accompanied by Sony’s Enhanced Imaging Processor (EIP).
The EIP enables the high-speed processing required for capturing high-definition video images, and allows an HDV camcorder to record and playback high-quality still images. The first professional high-definition application of this enhanced imaging technology is in the HVR-A1U model. EIP technology is also at the core of a new consumer product counterpart, the Sony HDR-HC1 Handycam.
“The combination of a 3-megapixel CMOS sensor with our Enhanced Imaging Processor enables a camcorder to capture and process high-definition video and still images with unprecedented levels of gradation and detailed image reproduction,” said Bob Ott, vice president of professional video and audio products for Sony Electronics’ Broadcast and Production Systems Division. “Building on our long history of imager and camera development, we’re now offering our customers yet another option to choose from among the many diverse HD acquisition tools in the Sony product family.”
A Family of HDV Products for Professionals
The new HVR-A1U HDV camcorder complements Sony’s first entry into the professional HDV market, the HVR-Z1U. Introduced last fall, more than 37,000 units of Sony HDV products have already been delivered to customers worldwide.
The new HVR-A1U model now offers professional videographers another option for the capture and playback of HD images. The HVR-A1U offers many of the same features as the HVR-Z1U, such as balanced audio, XLR inputs, SMPTE timecode, and a Carl Zeiss Vario-Sonnar T* Lens. However, its smaller footprint makes this camcorder ideal for applications where space is at a premium or extreme mobility is required. For example, potential applications may include mounting on a skydiver’s helmet or placement on the hood of a racecar.
Sony’s CMOS sensor produces natural and rich tones for both light and dark areas of an image. To achieve wide dynamic range, EIP technology employs an algorithm that separates image data into its texture patterns and brightness components.
CMOS-based technology helps eliminate the presence of smear, which is created by vertical bands of bright light stretching from the top to the bottom of an image’s “bright areas” and occurs when something extremely bright like a pin-point light source is shot.
Sony has reduced the size of the transistors within an image’s pixel matrix, allowing for a larger area of the photo-sensitive portion of the pixel and enabling more light to be taken in than with a conventional CMOS sensor. In addition, the Correlated Double Sampling circuits on the sensor achieve extremely low-noise image quality.
Sony’s CMOS-based sensor circuitry runs at lower voltage and consumes less power than conventional CCD-based processors, resulting not only in longer battery life but also allowing for the use of smaller batteries so the camcorders can be smaller overall.
The HVR-A1U can record and playback HDV, DVCAM, and DV content, with the ability to downconvert footage into standard definition. A widescreen Hybrid LCD monitor is also included. Other key features include:
· Still image capture – Maximum pixel size for still images is 2.8M (1920x1440) pixels in Memory Mode. Users can record 1.2M (1440x810) pixels in Tape and Play/Edit Mode.
· Histogram Indicator – Users can check the brightness of an object and easily adjust exposure by viewing this graphical presentation.
· Tele Macro – This feature enables users to capture a macro image from a distance, especially useful for shooting smaller moving objects, and it also provides the ability to make subjects more prominent against a backdrop and to suppress shadow projection.
Professional Media Optimized for HDV Applications
Sony’s highest-quality 6mm videotape, DigitalMaster, is the recommended professional media for HDV applications. These 63-minute cassettes (model PHDVM63DM) use Sony’s AME (Advanced Metal Evaporated) II Technology and its unique dual-active magnetic layers.
By improving on an already successful product, the new AME II manufacturing process employs Hyper Evaticle IV magnetic grains, improved lubricants, and a refined Diamond-Like Carbon (DLC) layer. DigitalMaster tape exhibits greater packing density of magnetic grains, higher retentivity, higher output, and lower noise. The result is a more robust tape with 60 percent fewer dropouts and 90 percent fewer errors.
The HVR-A1U HDV camcorder is expected to be available in early fall, at a suggested list price of less than $3,500.
Adobe Video Collection 2.5 Will Include Photoshop CS2
Adobe Systems Incorporated announced the Adobe Video Collection 2.5 Professional edition will now include Adobe Photoshop CS 2 software, a major upgrade to the package. Adobe Video Collection 2.5 Professional edition includes Adobe Premiere Pro 1.5, Adobe After Effects 6.5, Adobe Audition 1.5, Adobe Encore DVD 1.5, and now Adobe Photoshop CS 2 software. The addition of Photoshop CS2 will put even more power, precision and control in the hands of film and video professionals to create high-impact, broadcast-quality images and effects.
Adobe Photoshop CS 2 adds new features to the Adobe Video Collection Professional edition. The new Vanishing Point tool enables users to clone, paint and transform image objects while retaining visual perspective, reducing the number of steps needed to create realistic effects. Users can take advantage of 32-bit HDR color, YUV processing, and support for 16-bit Photoshop color images to achieve the highest color fidelity possible when working on HD or film projects.
FireWire Preview makes it possible to view projects on a television monitor through a new direct export feature during the creation process. With Smart Objects, users can scale and transform images and vector illustrations without losing image quality — as well as create linked duplicates of embedded graphics — so that a single edit updates across multiple iterations. In addition, the new Adobe Bridge, included with Photoshop CS2, makes it easy to organize, find and preview a wide range of media formats, including video.
Adobe Video Collection Professional edition for Microsoft Windows XP is immediately available to customers in the United States and Canada. International versions are expected to begin shipping in late May and early June.
Adobe Video Collection Professional edition is available at an estimated street price of US$1,499. Customers who own the previous version of Adobe Video Collection Professional edition will be eligible to upgrade for an estimated street price of US$399. Adobe Video Collection Standard customers can upgrade to Adobe Video Collection Professional for an estimated street price of US$799.
