Multimedia
Newsletters
Blogs
Whitepapers
Events
DCP Directory
Mill Directory
Edit Calendar
Advertisers
Reader SurveyHDV@Work
Nov 14, 1997 12:25 PM
Canon's HDV at 24fps: a revised look
By Steve Mullen
Over the last few months, two new HDV camcorders have come to market that offer 24 frames-per-second HDV video. The first to ship was JVC's GY-HD100, which offers progressive-scan CCDs and true 24p. The second, Canon's XL H1, provides 24fps video. The Canon XL H1 employs 1080-line interlace CCDs, while the JVC HD100 has 720-line progressive CCDs.
Canon does not claim it captures “24p” because its three 1.67 Megapixel CCDs do not capture a "progressively scanned" image. In this way, the XL H1 is like the Sony Z1 and FX1, which also use interlace CCDs.
At its website, Canon calls its “24fps mode” by the marketing name 24F. Canon claims 24F “gives the look and motion of film.” Clearly, the “look and motion of film” requires 24fps with a constant interval between frames.
The obvious process that could accomplish true 24fps is to clock the 1440x1080 CCDs at 48Hz. By clocking the CCDs at 48Hz, a constant stream of video frames is captured. This eliminates the non-equal time between frames of Sony's CineFrame 24. It also inherently supports a 1/48th second shutter, something not provided by CineFrame 24.
While Canon has a perfect right to withhold information on the process by which 24F is obtained, given the claim of film motion, the company should disclose whether 24F has a constant timebase. When I asked if the camera captured with a “constant timebase,” Canon representatives declined to answer.
Employing the Kell factor of .85 with a 1.33:1 (1440x1080) aspect-ratio image, the H1’s effective horizontal resolution should be about 920 lines. (The use of non-square pixels indicate effective vertical resolution should be about 700 lines.)
Interlace-scanning CCDs employ row-pair summation to reduce interlace line flicker and twitter. Row-pair summation reduces effective vertical resolution to almost 800 lines in 1080i60 mode.
In 24F mode, Canon could use its “DV Frame Mode” technique to read out the CCDs. This “vertical green-shift” mode employs every other field and creates the luma signal by adding Red+Blue pixels from rows 1 and 3 together with the sum of Green pixels in rows 2 and 4. This solution would yield about 600 lines of effective vertical resolution.
Another option would be to use Smart Deinterlacing to create each frame from both fields. While static resolution will be that of an interlaced frame (approximately 800 lines), resolution for moving objects (not the entire field) will be as low as that of a field (about 400 lines).
One possible marketing advantage of Smart Deinterlacing is that because resolution tests are inherently static, they indicate about 800 lines of effective vertical resolution. This would allow Canon to claim there is no loss in resolution between 60i and 24F. (Some Internet reports do indicate a test resolution of 800 lines.) Hopefully, anyone purchasing a $10,000 camcorder will realize that since video almost always has motion, de-interlacing cannot provide resolution equal to interlace scanning.
The Canon XL H1's DIGIC DV II chip outputs video with or without pulldown. The 24F data has 2:3 pulldown added to the odd and even lines of each de-interlaced frame to yield 1080i60. The 30F de-interlaced video is already 1080/60PsF (Progressive segmented Frames), while 60i is, of course, already 1080i60. Thus, 1080/60PsF and 1080i60 are output as 4:2:2 uncompressed video from the XL H1's HD-SDI port and from the analog port.
The 1080/60PsF and 1080i60 are also MPEG-2 encoded. Canon has supplied all major NLE vendors with XL H1 units so they can implement a capture process that enables 24F and 30F to be stored to disk as 24fps or 30fps video that is free of interlace artifacts.
Canon did provide sensitivity data for the XL H1 in both 1080i60 and 24fps modes. With the standard kit 20X HD lens (at wide angle) in Auto Mode and with a Gain of 18dB, the data are:
60i, 1/60 shutter speed = 7 lux
24F, 1/48 shutter speed = 6 lux
30F, 1/30 shutter speed = 4 lux
For the XL2, comparable data are:
XL2 with the standard kit 20X lens (measured at Wide Angle) in Auto Mode with a Gain 18dB:
60i, 1/60 shutter speed = 5.5 lux
24P, 1/48 shutter speed = 10 lux
30P, 1/30 shutter speed = 6.5 lux
These data indicate: (1) The H1, whose CCDs have about 2.5X more elements, is only slightly less sensitive than the XL2 in 60i mode, which is a major accomplishment; and (2) Canon’s 24F will deliver almost a half a stop greater sensitivity than shooting 24p using the XL2. Video Systems will soon review the XL H1.
Avid to synchronize product development on the Mac
Avid Technology announced its plans to synchronize development for its Mac product line in preparation for Apple’s introduction of Intel-based Macs next year. By synchronizing development for both Apple platforms, Avid’s initial Mac HD release is now targeted for mid-2006 for Avid Xpress Pro and Media Composer Adrenaline systems running on PowerPC Macs. Following the arrival of Apple’s Intel-based systems, Avid plans to deliver the same HD capabilities offered on PowerPC-based systems to Avid products running on the new Mac-Intel architecture. This development coincides with the company’s plans to achieve overall synchronization between Mac and Windows platforms by mid-2006.
“When Apple announced its plan to move to Intel processors this past June, we were as surprised as the rest of the industry, ” said Dana Ruzicka, vice president of post solutions for Avid. “The new Intel architecture shows great promise for improving Mac performance, but it also requires third-party developers to rework their roadmaps in order to support two Apple platforms. While this kind of wholesale change is good for the industry overall, we share our customers’ frustrations with the disruption it can cause in the short-term. Given how important the Mac is to our customer base, we’re embracing Apple’s Xcode development environment, which enables us to simultaneously develop for both PowerPC- and Intel-based Mac systems. Although our timeframe for delivering HD on the Mac is now mid-2006, our support of both the new Intel architecture and the existing PowerPC platform offers a path for all of our loyal Mac customers –- and helps us to better serve their needs in the long run.”
Avid editing systems running on PowerPC- and Intel-based Macs are expected to provide the following HD capabilities:
* HD editing support –-allowing users to edit major HD formats, including HDCAM, HDV, and DVCPRO HD.
* Avid DNxHD support and encoding –- enabling high-definition workflows at standard-definition data rates, but with the image quality of working at uncompressed HD resolutions.
* Realtime HD Multicam –- allowing simultaneous playback of all multicam views for on-the-fly editing in real-time.
For more information about Avid products and services, please visit: www.avid.com.
Media 100 announces Media 100 sw
Media 100, a provider of advanced editing systems for the corporate, broadcast, postproduction, and multimedia industries, has announced the availability of preorders of Media 100 sw. This software-only nonlinear editing solution uses media captured by Media 100i or Media 100 HD systems to edit, composite, mix, and export to DVD or Web. The product is expected to ship on November 15.
Featuring an intuitive and easy-to-learn NLE interface, Media 100 sw is a companion to existing Media 100 systems. While Media 100 sw currently does not capture or output to tape without the HDX video I/O board, all other functionality of Media 100 HD is included. Media 100 sw allows existing Media 100 users to add an affordable software-only NLE to their current workflow.
Media 100 sw can seamlessly interchange projects, programs, and media with Media 100 HD and all media from Media 100i. All existing import and export workflows, including sending to third-party compressors for MPEG-2 for DVD or MPEG-4 for web, continue to work as they do with the current shipping Media 100 HD product. A future standalone version will add support for FireWire capture and output from a range of DV and HDV decks and be available as an upgrade to the companion version. Version 1.0 key features include:
*Edit SD and HD material using the familiar Media 100 interface.
*Full media and graphics import/export capabilities as well as full support for all Media 100 codecs.
*Realtime effects and accelerated rendering (depending on processor and drive speeds).
*Fully integrated Boris Graffiti vector-based titling solution is included. Seamless interchange of media, bins, and programs to and from Media 100 HD.
*Supports media from Media 100i systems.
A comprehensive tutorial helps users to create a Media 100 sw program. Easy-to-use licensing includes Electronic Software Download (ESD) and a 14-day trial version. Media 100 sw will be shown at the NAB Post+ Production Show, along with Boris FX's integrated solutions. The exhibition takes place November 15-17 at the Javits Convention Center in New York.
Preorders of Media 100 sw are available through the Boris FX worldwide reseller channel or direct through Boris FX for $395 US SRP. The product is expected to ship on November 15. The version of Media 100 sw that adds FireWire support will sell for $649 SRP when it becomes available. Version 1.0 users will be able to upgrade to this version for $245 SRP.
