Using HDV cameras in the HD workflow
Apr 1, 2005 12:00 PM, BY DAVE BLACKHAM
 Table 1. This table of comparative formats shows that HDV is reasonable specified but highly compressed. Click here to see an enlarged diagram. |
Granada Bristol is a production center for observational documentaries and wildlife programs. Bristol is a hub for television documentary production and is located about 160km west of London.
Production teams are always looking for new equipment that can assist the shooting in difficult conditions or at remote locations. Now that much programming is commissioned in high definition, the facility was looking for replacements for the older DV and Betacam formats.
The HVR-Z1 camcorder is new from Sony, and the facility has found it produces some very pleasing results. Certainly, it is a big step on from its PD150 and PD170 predecessors. The camera can be used to record in either DVCAM or DV, or in the new ‘HD2’ HDV format. Using the camera to shoot pictures and sound for SD programs, capturing in either DV or HDV, the camera promises to perform well and will be of benefit to productions crews.
DVCAM capture, DV edit
When capturing media in HDV format for HD productions, the camera should not be thought of as another ‘true HD’ camera, but as a small, portable camera that could be used in situations where it is not possible to deploy larger HD or film cameras. It also can be used for HD special effects work, where the size and cost of deploying the camera could get shots not possible or affordable with larger and more expensive technology.
HDV capture, DV edit
There seem to be four potential workflows for the camera and the resulting media. No doubt, users will think of many others.
HDV capture, HDV edit
This workflow works fine. A significant benefit over some other similar-size cameras is the native 16:9 aspect ratio of the camera. Used as a compact true 16:9 DVCAM camera, the Z1 is a step forward in image quality and functionality over previous models.
Used as a small 16:9 camera capturing HDV and using the replay deck (Sony HVR M10E), the camera can be used to perform a down-convert to DV via the iLink down-converter and edit in a DV edit system. This appears to work equally as well capturing at DV on the camera. The benefit is that the images are of higher resolution on tape, so the possibilities of resize and other similar effects exist in post or perhaps maintaining an HDV archive.
HD camera-only
The resulting sequence could be used for inclusion into either SD or HD productions. So far, there isn't widespread availability of HDV edit, so evaluation is tricky to get reliable comparative results.
The HDV format
The results from HDV-captured and edited material is impressive. Using the HDV edit for inclusion in an HD sequence, the camera performs well, and the material can undoubtably be used in an interlaced HD sequence (or with a good adaptive deinterlacer) with some caveats. Avoid wide-angle shots, where a large-format HD camera or film technology would produce superior results. But, used as a small, cost-effective HD camera, the unit will fill a gap in the market.
Deployed as a small HD camera with an external HD converter, the camera could be put to good use. It could be used with an IEEE1394 and Y/C to HD-SDI converters and then recording to higher-quality HDCAM recorder or live to a switcher to give new production options.
When used in HDV recording mode, the camera records to the HD2 standard of recording (1080i) as opposed to the HD1 (720p) mode. Table 1 shows that HDV is reasonably specified but highly compressed.
While the Z1 is less sensitive by about one stop against the PD170 and two stops against the PD150, performance is adequate in low light. This could increase the noise floor if used in very low light, thus causing the likelihood of visible coding artifacts in the data stream. Limited tests performed with the Z1 did not suffer from any serious issues.
Progressive/interlaced capture
Sony advises a native ASA rating for the camera about 100. This compares with 500 ASA for the DVW 790 and 320 ASA for the HDW F900 with 180-degree shutter applied at 25p (so 620 ASA native).
The lens is a 1.6/4.5 — 54mm Carl Zeiss lens. Other users have suggested this limits the camera's performance. Tests confirmed that the camera would support better-quality optics. It is good for SD and reasonable in HDV, but a higher specification lens would push up the price of the camera.
How Granada Bristol is using HDV
The camera has a pseudo-progressive mode (Cineframe) that uses one field and then interpolates to give a complete frame. Using this mode and recording in DVCam mode seems to produce a useful “film” feel to the image with no appreciable loss in quality bearing mind the images seems to be processed in HD and then down converted to DV.
Used in HDV mode, the line-interpolation results in half the vertical resolution so in my view should be avoided. The use of HDV material in an HD production needs to have all the resolution going, so it is recommended to shoot only in the native interlaced modes. If the images are used in a progressive HD sequence, then use an adaptive de-interlacer. There are some good products on the market such as the de-interlacer in Final Touch by Silicon Color, Algolith or Revision's FieldsKit.
Granada Bristol is currently using the Z1 on shoots for UK-based observational documentaries, with improved results over the Sony PD150 or Panasonic DVX100A DV cameras, which the facility previously would have been used.
Small cameras such as this have always been an important part of the tool kit. They often used where larger cameras could not be used or where long shooting periods put the rental costs beyond program budgets. So, given the options of not getting the footage at all or perhaps losing a camera to hostile beasts, by adopting the Z1, the production team can shoot sequences at improved quality for its programs, plus stay in budget.
The facility also is using the camera for observational documentaries based in distant locations as a small ‘HD’ camera. It uses the camera where larger HD cameras cannot be deployed in hazardous locations, again giving good results.
Dave Blackham is Granada Television's Bristol operations manager. He would like to thank Nick Hill from Provision and Granada Television cameraman Andy Leonard for their help with the tests.
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