JVC GZ-HD7: World''s First 1920x1080 MPEG-2 Camcorder, Part 1

My JVC GZ-S3 Staticon camera and GZ-C3 VHS-C VTR circa 1983
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When I tested JVC''s DR-HD100 60GB hard-disk recorder for a review published in Broadcast Engineering (November 2006), I had the opportunity to experience both the advantages and disadvantages of hard-disk video recording. My conclusion was that the HD100 was a compromised by the need to carry it along with the camcorder. While I was happy with this kind of rig in 1983—it is not what I want today. The obvious solution is to eliminate a camcorder''s tape transport and replace it with a hard drive.

The JVC GZ-HD7 (MSRP of $1,799.95) features a three CCD imaging system.
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Each of the JVC GZ-HD7's 1/5in., 16:9 CCD has 570,000 elements that are progressively scanned every 1/60 second. Analog RGB signals from the CCDs are converted to digital data using 14-bit A/Ds. The Blue and Red CCDs are offset by one-half pixel from the Green CCD along both horizontal and vertical axes. Therefore, JVC uses the same resolution CCDs and employs similar pixel-shift technology as does Panasonic for its four-times-more-expensive AG-HVX200 P2 camcorder (click here for Barry Braverman's review of the HVX200). (The HD7''s resolution is approximately equal to the Panasonic HVX200.)

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The GZ-HD7 supports three MPEG-2 encoding modes: FullHD mode records five hours of 1920x1080i VBR at up to 30Mbps (26.6Mbps average); the “HDV equivalent” mode records five hours of 1440x1080 CBR at 27Mbps (the limit of D-VHS); and the SP mode records seven hours of 1440x1080i VBR at up to 22Mbps. For the latter two modes, each line is downscaled to 1440-pixels before encoding. For more, click here.

Stereo audio is encoded as MPEG-1 Layer 2 (MP2) at 384kbps. The video and audio elementary streams are multiplexed into a Transport Stream where each Data Packet has 192 bytes rather than the 188 bytes found in M2T files. This type of stream is called M2TS and the files are given a .TOD extension. A shock-resistant 1.8in. 60GB hard disk records the data stream.

Up to 25 minutes of SP can be recorded to a 4GB SDHC card so the GZ-HD7 is able to also perform as a sold-state HD camcorder. This opens the option to record video in physically demanding situations such as skydiving.

Left: 1440x1080; Right: 1920x1080
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To check encoder quality, I recorded cars speeding past the camcorder. I found no difference in MPEG-2 blocking artifacts between the 30Mbps VBR and 27Mbps CBR modes. I checked the 22Mbps VBR, SP mode the same way, and I was surprised to find no increase in artifacts.

Using Photoshop to check frame grabs, I concluded that although FullHD mode does not provide significant additional horizontal resolution, its greater luma and chroma recording bandwidth provides cleaner video with almost no aliasing. However, the quality difference is slight—so if your editing workflow requires HDV-equivalent video, you should not hesitate to use 1440CBR mode.

With the camera''s sharpness set at mid-point (default), the image has minimal edge enhancement artifacts in all recording modes. To subtly increase video clarity, I incremented sharpness by one tick. For the remainder of my testing, I used FullHD with Sharpness set at +1.

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Although designed by JVC''s consumer group, the GZ-HD7 has exposure controls that emulate those of “pro” video cameras. They provide the option of shooting under full manual, semi-automatic, and full automatic control. This flexibility enables a pro to choose the amount of automation required in each shooting situation.

Conversely, if you are new to shooting HD, you can shoot using the camera''s excellent Full Auto mode. As your shooting skills develop, you can learn to use the manual controls. Consumer camcorders that either lack a complete set of exposure and focus controls, or that hide these controls under menus, cannot offer you a real growth path.

• Shutter Priority Mode: You set shutter speed by pressing the "S" button. Use the setting dial to increment or decrement shutter speed from 1/2 second to 1/4000 second.
• Aperture Priority Mode: Similarly, you set aperture by pressing the "A" button. Use the setting dial to increment or decrement the iris: 1.8/1.9, 2.0, 2.8, 4.0, 5.6, and 8.0.
• Full Manual Mode: You can also independently set shutter speed and aperture. However, if AGC is enabled, in low-light situations AGC has the ability to increase or decrease exposure. Because the aperture setting has no mid-stops, I recommend the “exposure bias” technique.
• Exposure Bias Function: The Exposure Bias function can be used when the camcorder is in Shutter Priority mode, Aperture Priority mode, or neither mode (i.e., standard AE operation). Press the "Bright" button and use the setting dial to decrement or increment exposure in 1/3-stop steps. To fully lock exposure, press and hold the setting dial for a second.
• Run-and-Gun Exposure Setting: In high-contrast situations, nudge the LCD-mounted joystick right for Programmed AE menu. Now select Spotlight mode, which decreases auto-exposure by 2/3 stop. This effectively eliminates burned-out highlights.

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For backlit situations, you can press the camera''s "Backlight" button to increase auto-exposure by 2/3 stop.

By pressing the "Backlight" button twice, the camera switches to spot-metered AE. As those shooting widescreen know, the center of your composition is typically unimportant—so JVC enables you to use the joystick to move the spot-meter from the center to either side of the frame. To lock exposure, press and hold the joystick for several seconds.

None of the exposure controls require you to use the camcorder''s system setup menu. Very nice!

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Like most consumer camcorders, the HD7 has been tuned to image Caucasian skin as a “healthy” pinkish-tan rather than a more accurate pale white. This red push, plus the camcorder's saturation level, can lead to “sunburned” faces. Therefore, I recommend these settings: use MWB for artifical illumination; use AWB (or MWB) under Sunlight; use MWB under Overcast/Cloudy, and Open Shade; use Fine for Daylight Fluorescent Illumination; and use Cloudy when shooting indoors and the majority of
illumination is from skylight.

The HD7's latitude and vertical smear are typical of CCD-based camcorders.
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I estimate the GZ-HD7 has about a 9-lux sensitivity with AGC enabled. (That would be a Japanese rating of 18 lux.) If I'm correct, a 9-lux sensitivity will be a significant negative to many shooters. According to JVC, the maximum gain applied in AGC mode is +18dB—although my estimate is +12dB. Whatever the numbers, the GZ-HD7 is very useable in most situations where there was a normal level of illumination. When you need to avoid video gain noise, simply engage Twilight mode to limit gain to about +6dB.

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Fujinon supplies the Everio''s 10X optical-zoom lens, which maintains nearly the same brightness (f/1.8-f/1.9) throughout its f=3.3mm-to-33mm optical zoom range (a 35mm equivalent of 39.5mm to 395mm). Unlike most lenses, the Fujinon has little lateral chromatic aberration on high-contrast objects.

To focus, you can use either auto or manual focus. With manual focus, you will likely want to engage Focus Assist. The 207,000-pixel, 2.8in. LCD and large 0.57in., 269,000-pixel color VF will now switch to black and white. Use the wonderful wide rubber ring on the lens to adjust focus. Edges in sharp focus can be outlined in red, blue, or green.

Because the focus ring drives an “inner focus” servo system, you do not need to zoom to full Tele before you focus. However, if you plan to zoom in during a shot—before the shot—zoom in to the maximum point of your planned zoom and focus. If you don''t plan to zoom, or plan to zoom back, frame your shot and focus.

You can enable AF with the Focus Assist system engaged so you can monitor AF operation. Allow AF to achieve focus and then disengage AF before the shot. While AF worked well under good illumination, in low-light, I did not find AF useable as it “hunted.”

Unless you have the HD7 on a tripod, even with a very steady hand, you will not want to zoom past 3X because of the camera''s dreadfully ineffective OIS system. Thankfully, at 3X, the 35mm equivalent focal length is about f=140mm—a more than an adequate “medium-tele” focal length.

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The HD7''s audio limiter effectively prevented clipping. Moreover, there was no “pumping” of the audio level from gain added at low signal levels. Unfortunately, the omni-directional surface mounted stereo mic is exceedingly sensitive to wind, even with Wind Filter engaged. When there was no breeze, the integral mic sounded fine. When you plug in an external mic to the 1/8in. stereo “power-plug” jack, dual level meters are displayed.

The HD7 camcorder has an industry standard four-pole, 1/8in. AV jack. Unfortunately, whoever designed the original AV jack specification a decade ago made it incompatible with all 1/8in. headphone plugs (circles). The solution is simple: head to Radio Shack and buy an iPod cable plus an “in-line” 1/8in. female stereo jack. Wire as shown in the diagram at right.

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The GZ-HD7 can capture 1920x1080 16:9 stills or 1440x1080 4:3 stills to the disk or to an optional SD/SDHC memory card. You can also capture 1920x1080 stills from video clips on the harddrive or memory card to the memory card.

One of the benefits of any camcorder with random access storage is the number of pre-edit functions you can execute. Functions include browsing thumbnails of what you''ve shot; assigning shots to categories; browsing by category; deleting clips; protecting clips from deletion; and viewing clips in forward or reverse (normal, frame-by-frame, slow, fast, or clean pause). You can also skip from clip to clip plus create one or more playlists. Once you review shots stored on random-access media, you will never want to go back to tape.

The Everio is equipped with three digital interfaces: i.LINK, HDMI, and USB. I used the HDMI port for viewing all my test footage. HD-recorded material can be output via analog component jacks plus downconverted for output in SD via the analog component and composite/S-Video output jacks. When the “Video/S Output” menu is set to 16:9, output is anamorphic. When set to 4:3; output is letterboxed.

Based on a menu setting, the i.LINK port is output as “DV25” or “MPEG-2.” (HDV can be output only from video shot in 1440CBR mode.) The DV25 data stream can be recorded as anamorphic 4:3 video by a DV camcorder/VTR, DVD recorder, or NLE. MPEG-2 can be captured by an NLE that supports HDV. Interestingly, I was able to clone 1440CBR 27Mbps data streams to a Sony 1080i HDV VTR. Note that only a playlist can be output via i.LINK. Therefore, the clips you want must be entered into a playlist.

After several months of testing—including an informal comparison with an HDV CCD camcorder three times more expensive—I came away very impressed with JVC''s GZ-HD7. Given its incredibly low cost, for those who are willing to invest the time to learn how to use its many features, it is a great value. (See www.mindspring.com/~d-v-c to learn about an available GZ-HD7 Guide.) In Part 2, we will learn how the USB port supports a wide range of workflows using both OS X- and PC-based NLEs.