How does the AJ-HDC27V acquire and record at 24P?

Though the camera section of the AJ-HDC27V can acquire at 24 frames per second (fps) progressive scan (and various other frame rates), the VTR section always records at a constant 60-fps progressive scan, yielding a standard HDTV 720p/60 format tape. In fact, this is the case regardless of the frame rate at which the camera section is acquiring, which is a particularly important feature that avoids audio synchronizing issues in post production, or the requirement for the use of a parallel audio recording system. To create the 60fps signal for tape recording from the 24fps camera output, the AJ-HDC27V utilizes an adaption of the proven telecine technique of 2:3 pulldown -- except in this case, it is applied to convert a 24fps HD signal to a 60fps HD signal, rather than a 24fps film reel to a 60 fields per second NTSC video signal.

What is the image quality of the AJ-HDC27V?

The AJ-HDC27V camera provides 1280 x 720 pixel progressive scanning at all supported frame rates up to 60fps. A full bandwidth 4:2:2 10-bit resolution HD-SDI BNC output is available for line recording onto Panasonic's full bandwidth 4:2:2 10-bit resolution D-5 HD studio mastering format VTRs (AJ-HD2700 and AJ-HD3700). An internal DVCPRO HD format recorder in the AJ-HDC27V provides a highly mobile, economical, and high quality field production camera/recorder which is also capable of recording progressive scan images at up to 60fps, but at 8 bit resolution on tape. Therefore, for critical studio applications such as green screen compositing, we recommend that test shoots are performed to compare the results of DVCPRO HD and D-5 HD recordings, respectively. Regardless of the recording medium chosen, AJ-HDC27V images provide a rich, film like quality and the camera provides an extremely wide latitude, with unusually well defined blacks and excellent highlight handling capabilities.

What other frame rates does the AJ-HDC27V offer?

The AJ-HDC27V supports a wide range of progressive scan frame rates other than just 24fps. Operators can either select TimeLapse mode or any frame rate between 4pfs and 33fps, plus 36fps, 40fps and 60fps progressive. By varying both frame rate and shutter speed, the AJ-HDC27V operator can simulate many of the characteristics of film cameras including " undercranking" and "overcranking", realizing smooth speed changes when the final material is played back at 24fps. As previously described, regardles of the frame rate of the camera section, the recording section always records at 60fps, which avoids potential audio synchronizing issues later in post production.

In order to create a 60fps signal for tape recording from a camera that is acquiring at a wide variety of frame rates other than 24fps, the AJ-HDC27V simply modifies the pulldown pattern - for example at 12fps the pulldown pattern is 5:5, at 24fps it is 2:3, at 30fps it is 2:2, and at 60fps it is 1:1, which all yield 60fps for recording to tape.

What shutter speeds are available on the AJ-HDC27V?

The AJ-HDC27V offers the following shutter speeds: 1/100, 1/120, 1/250, 1/500, 1/1000 and 1/2000 sec. This feature, in combination with adjustable frame rates, allows the AJ-HDC27V to achieve motion-blur, warp-speed, stutter, and other in-camera effects. Frame-by-frame recording of varying durations and time between capture provide for built-in stop-motion and time-lapse photography capability.

What is the maximum recording time on a AJ-HDC27V?

Irrespective of the frame rate selected for the AJ-HDC27V camera section, the internal DVCPRO HD format recorder provides a maximum record time of 46 minutes per cassette. Similarly, with an external D-5 HD format recorder a maximum record time per cassette is 2 hours. HD video servers and HD NLE systems accepting a 720p line output from the camera head will be limited only by their available disk capacity.

How do I perform a standard definition finish with 24fps footage acquired by an AJ-HDC27V ?

As previously described, the AJ-HDC27V utilizes an adoption of the proven telecine technique of 2:3 pulldown to convert a 24fps HD signal in the camera section to a 60fps HD signal recorded on tape. For offline editing and standard definition finishing, downconversion to NTSC or component 525 (480i) line video is all that is required to initiate an NLE or tape-to-tape edit. The final result is analogous to a film to tape standard definition telecine transfer. Standard 30fps timecode is used in both HD master and SD downconverted signal cases; audio timing is also unaffected by downconversion. Internal HD to SD downconverters are available on all D-5 HD and DVCPRO HD tape recorder models, including the AJ-HD130DC field portable recorder.

How do I perform a high definition finish with 24fps footage acquired by an AJ-HDC27V ?

In high definition, there are several choices for editing AJ-HDC27V footage -- using 720p/60 and 1080i/60 formats or 720p/24 and 1080p/24 formats. In the case of 720p/60 editing, several HD production switchers and NLE systems now offer 720p/60 image processing. In the case of 1080i/60 editing, it is necessary to convert from 720p/60 to the 1080i/60 format. Provided that an internal format converter option card has been installed in the VTR, this can be performed during the edit session or at digitization directly from the output of a D-5 HD format recorder such as AJ-HD2700 or AJ-HD3700 or an AJ-HD150 DVCPRO HD format recorder.

In the case of 1080p/24 editing, the 2:3 pulldown sequence recorded by the AJ-HDC27V must be removed from the 720p signal and the source footage converted to 1080 progressive resolution. This can be easily accomplished by dubbing the source footage via a Panasonic AJ-UFC1800 Universal Format Converter to the desired 1080p/24 format editing recorder or HD NLE system. The 720p/24 format has recently been implemented in HD NLE systems from a variety of manufacturers, and offers a substantial reduction in required disk space per hour of stored footage, but it is not available as a tape-to-tape editing format at this time.

How do I convert variable frame rate footage shot with the AJ-HDC27V back to 24fps footage ?

Panasonic offers a hardware based Frame Rate Conversion to provide this function and is working with key NLE manufacturers to provide full support for variable frame rate digitization and conversion functions. As previously described, the AJ-HDC27V adds additional frames via the process of pulldown at the camera section output in order to make a constant frame rate of 60 frames per second at 720p resolution recorded on tape - a HDTV standard 720p/60 signal format. This pulldown sequence necessarily varies as the camera frame rate varies, so in order to identify which of the frames recorded to tape have new information, and which frames have repeated information, the AJ-HDC27V writes into the timecode user bits recorded on tape a mark for all "Active" or "new information" frames. Frames that are simply "Repeat" frames -- that is, frames duplicated by pulldown process in order to create a standard 720p/60 HDTV recording -- do not carry the mark data.

On playback through a Panasonic Frame Rate converter, these frame markers are used to control a variable frame rate recording cycle within the Frame Rate Converter. In this process the Frame Rate Converter only records the "Active" frames, and discards all "Repeat" frames. By playing back the "Active" frames at a frame rate of 24fps, the desired variable frame rate to 24 frames per second conversion is easily achieved. The Panasonic Frame Rate Converter can either output a 1080p/24 resolution signal for use with a 1080p/24 format recorder or HD NLE, or can re-insert 3:2 pulldown and provide a 720p/60 resolution output signal as desired.

Many HD NLE systems are also developing support for this technique, and after variable frame rate digitization may either convert to 1080p/24 resolution, or support 720p/24 native editing which provides significant savings in required disk space per hour of recorded material.