Multimedia
Blogs
Forum
Affordable HD
Whitepapers
Newsletters
Events
Advertisers
DCP Directory
MillimeterHDV@Work
Feb 22, 2005 12:52 PM
HD Distribution Using D-VHS
Steve Mullen
Ask most folks in the video industry “what is D-VHS?” and you are likely to get a puzzled look. This lack of knowledge is especially prevalent among those buying Sony’s FX1 or Z1 cameras. These folks are often convinced they have only two distribution options -- use the WM9 HD encoder or wait until high-definition DVD recorders arrive late this year.
Ask a home theater aficionado what D-VHS is, and you’ll get a far more knowledgeable answer. D-VHS is well known because some buy D-Theater pre-recorded movies in the 1080i format with Digital Dolby 5.1 soundtracks. D-VHS also allows those with i.LINK-equipped HD set-top boxes to record clones of HD programming.
Now D-VHS has a new role as a very affordable (street price about $500) way of distributing HD productions. But what exactly is D-VHS? The primary ingredient is a VHS transport. Add to this base all the usual electronics that go with any VHS deck.
What adds the “D” to VHS is the inclusion of several unique functions. A standard definition MPEG-2 encoder is the primary “digital” component. It can encode three sources: the internal NTSC tuner, composite and S-Video inputs, and DV via an i.LINK port.
The i.LINK port can also input and output 720p30, 720p60, 1080i50, and 1080i60 MPEG-2 data streams. Data from this port can be recorded at up to 28.2Mbps in “HS” mode. JVC 720p HDV products can be connected directly, via i.LINK, to a D-VHS deck to make clones of HDV tapes. (Unfortunately, in my tests, Sony’s 1080i HDV cannot be cloned to D-VHS.) Two D-VHS tape cassettes are available. The DF-300 cassette, which has a 31.7GB capacity, can record 2.5 hours at the HS rate. The DF-420 cassette, which has a 44.4GB capacity, can record 3.5 hours at the HS rate. Talk about an inexpensive all digital MPEG-2 archiving format!
JVC D-VHS decks have an optical digital audio port that outputs either Dolby Digital 5.1 or 48kHz PCM audio. While most editing applications export only a PCM stereo soundtrack, others paths offer the potential to record an AC-3 soundtrack. You can edit widescreen HDV and add a Dolby 5.1 soundtrack to your production.
If you need to drive an HDTV from your computer, connect the HDTV via analog component to a D-VHS deck. Now feed, via i.LINK, either 720p or 1080i through the deck from the computer. The deck will act as a realtime MPEG-2 digital-to-analog converter.
A JVC D-VHS deck can be used as a downconverter for HD MPEG-2 input via i.LINK. For example, you can record videotape or burn a DVD in realtime using the D-VHS deck as an HDV-to-NTSC/PAL converter. Connect your tape deck or DVD recorder to the D-VHS deck via S-Video. On the D-VHS deck, select “Convert all to 480i” and select “4:3 monitor” if you want a letterboxed copy, or “16:9 monitor” if you want an anamorphic-widescreen copy. This procedure will work for both 720p and 1080i HDV.
There are three models of JVC D-VHS decks you can use for these applications: the HM-DH30000U, HM-DH40000U, and the SR-VD400US.
The HDV Sweet Spot: 720p30
By Steve Mullen
NLE playback performance is based on the number of pixels in an MPEG-2 frame. Table 1 shows these values for 720p30 and 1080i60 video. Also shown are values for 720p60, which, were it to become available, moves more pixels than does 1080i30 during each 1/30 second.
Simply put, with 1080i30 video, every MPEG-2 decode will require either nearly twice the computing power or nearly twice the time -- or some increase in both. One option is to edit MPEG-2 without the need to demux and transcode. This is possible with native HDV editors running under XP. (No native Mac NLE yet exists.) At NAB 2004, the president of a company highly regarded for its codec development and NLE systems told me that realtime editing of native 1080i would require a dual 3.2GHz Xeon PC. That is turning out to be true.
There is another way to look at the issues of 1080i editing. That is to appreciate the “sweet spot” that 720p30 represents. The 1280x720 HDV format has the inherent advantage of progressive scanning. Progressive scanning yields an image with no interlace flicker, no interline twitter, no motion artifacts, and more efficient encoding that minimizes MPEG-2 blocking artifacts.
Because interlaced cameras must use CCD row-pair summation in order to suppress interlace flicker and interline flicker, effective vertical resolution is reduced by 25 percent. Therefore, the 1080-line interlaced format will carry an image that has about 800 lines of vertical resolution -- not much more than the 720 lines provided by 720p.
There’s very little difference between the effective horizontal resolution of a 1080i camera that uses three 960x1080 CCDs and a 720p camera that uses three 1280x720 CCDs. In short, there will be little if any visible resolution difference between these 720p and 1080i HDV camcorders.
Blackmagic Design Announces DeckLink for Mac OS X 4.8
Blackmagic Design has announced the immediate availability of DeckLink for Macintosh v4.8 software, which includes new features for all users of the company's popular DeckLink family of standard definition and high definition broadcast video cards.
New features include HD downconversion on capture for DeckLink HD models, Photoshop plug-ins that directly integrate 8- or 16-bit video frame capture and output via DeckLink cards in the popular graphics application. Also included in this release are single field pause, 12 channel HD-SDI audio support on DeckLink HD models, and improvements in compatibility with the voice over tool in Final Cut Pro HD.
DeckLink for Mac OS X v4.8 is available now to all DeckLink users at no charge, and is downloadable via the Blackmagic Design support website.
New features include downconversion on capture from HDTV 1080/23.98p/50i/59.94i video inputs. Capture an HDTV 1080 signal to a standard-definition file, in letterbox or anamorphic format, in realtime and with timecode intact with any DeckLink HD series card. This enables a seamless workflow between offline and online projects for the first time in one pass. Supported SD formats include 8- and 10-bit uncompressed, PhotoJPEG, DV or DV50.
HD 1080/59.94i output from an HD 1080/23.98p timeline in Final Cut Pro HD in realtime 3:2 pulldown is now supported in high definition. All DeckLink HD series cards can now play out HD 1080/23.98p media at HD/59.94i fps. This feature is extremely useful for monitoring purposes. HD monitoring and or preview can be done with a domestic HDTV, cutting costs of monitoring high-definition media.
The new Photoshop plug-in adds support for grabbing a still frame from the DeckLink video input directly into Adobe Photoshop. Plug-ins support both 8- or 16-bit RGB for full bit depth frame grabs. The new export plug-in for Photoshop allows still frames and graphics to be output to DeckLink's video output. This also includes alpha channel conversion to key output on DeckLink Pro cards, while other DeckLink models can use alpha channel for internal keying. This feature is specifically designed to enhance workflow for broadcast designers.
Single field pause eliminates flicker when playback is paused in a similar way to how many broadcast decks pause video. When editing video that has 3:2 pulldown or other field movement, this setting can allow for a much cleaner video display because interlace is removed. When playback is commenced, output is normal full field quality.
Voice Over Tool is supported in Final Cut Pro HD, enabling the user to capture voice over commentary and or voice over timing for pacing of the sequence.
Twelve-channel HD-SDI audio output supports the HDCAM SR deck, as well as professional video hardware such as DeckLink Multibridge. Eight-channel audio output is available via SD-SDI embedded audio.
16x9 Offers Improved Zoom Control for LANC HDV Cameras
16x9 Inc. has introduced a new version of the Zoe zoom control designed for use with the Sony HDR-FX1 and HVR-Z1U, Canon XL2, plus other LANC cameras. Ideal for digital cinematography, the Zoe-DVL provides variable stepless zoom speed control with preadjusted maximum speed, focus, record start/stop, and camera on/off in an efficient, operator-friendly package. The Zoe-DVL is priced at $360.
Featuring a more ergonomic design, the Zoe-DVL offers three thumb positions -- left, right, or center -- for greater comfort and control. The unit’s hallmark touch responsive rocker switch is engineered for intuitive operation. Zoom speed increases in direct relation to pressure applied to the zoom button, which allows for smooth ramp-up and precise manipulation. A rotating selector wheel provides preadjustment of maximum zoom speed.
Constructed of lightweight, durable polycarbonate, Zoe’s housing sports a streamlined new look. Mechanical side guards protect the selector wheel from damage or accidental repositioning. Separate buttons offer instant adjustment of focus and camera on/off functions. Controls are set apart and uniquely shaped for easy touch recognition. Functions are clearly indicated by bright LEDs.
Set up is quick and easy. The new 11.8in. (30cm) coiled cable extends to 35in. (90cm). A rugged elbow plug connects to the camera’s LANC output. Zoe’s improved quick-release clamp attaches to tripod panhandles of up to 34mm diameter.
Media 100 and Lumière HD Announce
HDV Support for Media 100 HD
Media 100 has announced Media 100 HD compatibility with High Definition Video (HDV) via Lumière HD. Through a software codec featuring Lumière HD support, customers will be able to shoot their projects cost effectively in the HDV format and, without additional hardware, bring the footage in for editing with all the 10-bit, Macintosh-based power of Media 100 HD.
"HDV cameras are taking the world by storm. The level of integration demanded by the marketplace is to have all the benefits of HD with the convenience of FireWire," said Steve Bayes, director of product marketing, Media 100 Business Unit. "By interfacing with Lumière HD, we are giving Media 100 HD customers the best of both worlds: a truly unique multi-format HD and SD editing environment together with the flexibility to shoot with an HDV camera and capture and transcode using whatever QuickTime codecs are loaded on their systems."
Producers may encode their HD output into an HDV MPEG-2 transport stream and transfer back to HDV cameras and decks, or produce masters for other formats, such as DVD. For producers not working in an SDI facility, support for HDV via Lumière HD, a standalone software, enables Media 100 HD customers to maximize this new shooting medium while saving on the costly equipment and infrastructure typically needed to shoot, convert, and deliver in high-quality HD.
"Lumière HD is the missing link to getting HDV material rapidly and easily from an HDV camera to an editing system," said Lumière HD President Frederic Haubrich. “We support the top HDV cameras from JVC and Sony, including the world's first 1080i HDV camera, the Sony HDR-FX1(E). Media 100 HD is a robust system with high-value HD and SD editing capabilities. We are pleased that, via Lumière HD support, the expanding community of savvy content producers and editors will now have the choice to shoot HDV."
