HDV is a format for recording of high-definition video on DV cassette tape. The format was originally developed by JVC and supported by Sony, Canon, and Sharp. The four companies formed the HDV consortium in September 2003.
Conceived as an affordable high definition format for digital camcorders, HDV quickly caught on with many amateur and professional videographers due to its low cost, portability, and image quality acceptable for many professional productions.
HDV and HDV logo are trademarks of JVC and Sony.
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. If an aperture is wide, then uncollimated rays are admitted, resulting in a sharp focus only for rays with a certain focal length. This means that a wide aperture results in an image that is sharp around what the lens is focusing on. The aperture also determines how many of the incoming rays are actually admitted and thus how much light reaches the image plane (the narrower the aperture, the darker the image for a given exposure time). In the human eye, the pupil is the aperture.
An optical system typically has many openings, or structures that limit the ray bundles (ray bundles are also known as pencils of light). These structures may be the edge of a lens or mirror, or a ring or other fixture that holds an optical element in place, or may be a special element such as a diaphragm placed in the optical path to limit the light admitted by the system. In general, these structures are called stops, and the aperture stop is the stop that determines the ray cone angle, or equivalently the brightness, at an image point.
In some contexts, especially in photography and astronomy, aperture refers to the diameter of the aperture stop rather than the physical stop or the opening itself. For example, in a telescope the aperture stop is typically the edges of the objective lens or mirror (or of the mount that holds it). One then speaks of a telescope as having, for example, a 100 centimeter aperture. Note that the aperture stop is not necessarily the smallest stop in the system. Magnification and demagnification by lenses and other elements can cause a relatively large stop to be the aperture stop for the system.
Sometimes stops and diaphragms are called apertures, even when they are not the aperture stop of the system.
The word aperture is also used in other contexts to indicate a system which blocks off light outside a certain region. In astronomy for example, a photometric aperture around a star usually corresponds to a circular window around the image of a star within which the light intensity is assumed.
Shutter Speed
The camera's shutter speed, the lens's brightness (f-number), and the scene's luminance together determine the amount of light that reaches the film or sensor (the exposure). Exposure value (EV) is a quantity that accounts for the shutter speed and the f-number.
Multiple combinations of shutter speed and f-number can give the same exposure value. According to exposure value formula, doubling the exposure time doubles the amount of light (subtracts 1 EV). Making the f-number one stop brighter (reducing the f-number by a factor of \scriptstyle \sqrt{2}) also doubles the amount of light. A shutter speed of 1/50 s with an f/4.0 lens gives the same exposure value as a 1/100 s shutter with an f/2.8 lens, and also the same exposure value as a 1/200 s shutter with an f/2.0 lens.
In addition to its effect on exposure, the shutter speed changes the way movement appears in photographs. Very short shutter speeds can be used to freeze fast-moving subjects, for example at sporting events. Very long shutter speeds are used to intentionally blur a moving subject for artistic effect. Short exposure times are sometimes called "fast", and long exposure times "slow".
Adjustment to the aperture controls the depth of field, the distance range over which objects are acceptably sharp; such adjustments need to be compensated by changes in the shutter speed.
Gain and ISO
Some cameras and camcorders have both an adjustable ISO setting and a Gain setting. Which one should you use or should you use both?There are differences between the two settings, but for all practical purposes, they control the same aspect of video. You may not remember film, but in those days all films were rated with an ASA rating which today is called an ISO rating. Kodachrome, for instance, was a Kodak film used in both cinematography and still photography. For movies it was available in 8mm, 16mm, and 35mm. It was also available in various ISO/ASA ratings from 24 to 200. The ISO determined how much light was required. The smaller ISO ratings required more light, but had a finer grain and created better images. Larger ISO numbers required much less light, but looked grainy. Higher quality images required a low ISO rating.In many video cameras and DSLRs, you can dial in the ISO which is helpful when you need more light sensitivity. The cost is degraded images which show more grain.The size of the digital camera’s image sensor dictates what ISO setting provides the least amount of digital noise. Larger sensors produce less noise or grain. Smaller sensors produce more digital noise at higher ISOs (like 800). Digital camera image sensors are designed to perform best at the lowest ISO, just like with film. On most digital cameras this is ISO 100, although some high end DSLRs the ISO rating is as low as 25.The larger Full Frame sensors are the size of a 35mm frame. They allow for more and larger pixels to be packed onto the image sensor, producing smoother, grain-free images at higher ISO settings sometimes as much as 1600 ISO. Like film, the lower the ISO rating of the camera sensor, the better the image quality is going to be.The major reason to use ISO rather than gain is to correlate the camera sensitivity with a light meter. Light meters must be adjusted to the ISO. The meter measures the amount of light and its internal computer indicates which f-stop and shutter speed is needed for a particular ISO. Cameras have built-in light meters which measure the light and in auto mode set your camera to an f-stop and shutter speed to make an ideal exposure. If there is not enough light, the meter opens the iris and increases the shutter. If these are not enough, it raises the ISO of the camera which degrades the image by adding grain.
White Balance
In photography and image processing, color balance is the global adjustment of the intensities of the colors (typically red, green, and blue primary colors). An important goal of this adjustment is to render specific colors – particularly neutral colors – correctly; hence, the general method is sometimes called gray balance, neutral balance, or white balance. Color balance changes the overall mixture of colors in an image and is used for color correction; generalized versions of color balance are used to get colors other than neutrals to also appear correct or pleasing.
Image data acquired by sensors – either film or electronic image sensors – must be transformed from the acquired values to new values that are appropriate for color reproduction or display. Several aspects of the acquisition and display process make such color correction essential – including the fact that the acquisition sensors do not match the sensors in the human eye, that the properties of the display medium must be accounted for, and that the ambient viewing conditions of the acquisition differ from the display viewing conditions.
The color balance operations in popular image editing applications usually operate directly on the red, green, and blue channel pixel values, without respect to any color sensing or reproduction model. In shooting film, color balance is typically achieved by using color correction filters over the lights or on the camera lens.
Depth of field
In optics, particularly as it relates to film and photography, depth of field (DOF) is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image. Although a lens can precisely focus at only one distance at a time, the decrease in sharpness is gradual on each side of the focused distance, so that within the DOF, the unsharpness is imperceptible under normal viewing conditions.
In some cases, it may be desirable to have the entire image sharp, and a large DOF is appropriate. In other cases, a small DOF may be more effective, emphasizing the subject while de-emphasizing the foreground and background. In cinematography, a large DOF is often called deep focus, and a small DOF is often called shallow focus.
HDV’s Function
From the outset, the HDV 1080i specification of the HDV* format has been developed to record stunning HD images with 1080 active scanning lines on DV-specification cassette tapes. It adopts the MPEG-2 compression format, using 8-bit digital component recording at approximately 25 Mb/s, which is the same data rate as the DVCAM/DV format, enabling a long recording time on compact DV cassettes. For example, more than 60 minutes of high-quality HD images can be recorded on a mini DV cassette. As with the DVCAM and DV formats, the HDV format allows an i.LINK connection to compatible nonlinear editors, enabling a cost-effective HD production system. The sheer volume of HDV 1080i professional and consumer equipment used around the world is a clear indication that HDV 1080i has become one of the most popular HD formats.
Product Description
The compact professional camcorders manufactured by Sony have introduced a new level of mobility for ENG and documentary-making worldwide with their superb quality and compact dimensions. These camcorders have dramatically revolutionized the traditional methods of capturing video footage. With the new Sony HVR-V1U camcorder, now you can enjoy the same mobility with the breathtaking beauty of 1080/24P shooting, and have the freedom to create video material with much greater creativity and visual impact. The HVR-V1U will pave the way into a new world of HD video productions.
From the Manufacturer
Manufacturer Description The compact professional camcorders manufactured by Sony have introduced a new level of mobility for ENG and documentary-making worldwide with their superb quality and compact dimensions. These camcorders have dramatically revolutionized the traditional methods of capturing video footage. With the new Sony HVR-V1U camcorder, now you can enjoy the same mobility with the breathtaking beauty of 1080/24P shooting, and have the freedom to create video material with much greater creativity and visual impact. The HVR-V1U will pave the way into a new world of HD video productions. Overview
How it’s done Our professional HDV products offer exceptional quality - only made possible by Sony’s cutting-edge technical expertise. Our world-class semiconductor manufacturing technologies have enabled the development of a new CMOS sensor that offers the image quality to satisfy the most demanding professionals. Employing a 3-chip system, the 3 ClearVid CMOS sensor offers high-resolution images with rich and natural colors. Coupled with advanced technology such as the Sony Enhanced Imaging Processor and a high-quality Carl Zeiss Vario-Sonnar T lens, the full power of this imaging system is realized in the HVR-V1U camcorder. "Ready-to-edit" with the HVR-DR60 hard disk recording unit Video professionals can be confronted with tight production schedules, and balancing time with creativity can become a dilemma. The Sony HVR-DR60 frees you from such dilemmas by allowing instant editing of your video footage. The HVR-DR60 offers a unique hybrid concept, in which video material can be recorded to the hard disk and the camcorder tape simultaneously with time code synchronized. Simply connect the HVR-DR60 to a PC running compatible nonlinear editing software. The computer will immediately recognize the recorded data files for a dramatic improvement in editing efficiency. With the HVR-DR60 hard disc unit, the time-consuming digitizing process is a thing of the past. Another huge appeal of this Hybrid configuration is its improved efficiency in archiving operations. With your source footage available on tape and hard drive, you can immediately store the source tape in your video library without making copies to other media. Your work footage is already there on the HVR-DR60 hard disk. Further more, the HVR-DR60 has been developed by Sony as a perfect companion for the HVR-V1U. Sony’s HDV product lineup has been further expanded, giving you the freedom to be even more productive. Offering HD quality in a compact, lightweight, and mobile design
Progressive 1080/24p -- progressive shooting The HVR-V1U camcorder provides 1080/24p acquisition with 2:3 pull-down recording - compatible with existing Sony professional HDV equipment. The 24p scan signals are recorded on tape as 60i signals through means of 2:3 pull-down. Similarly, a 30p scan signal is recorded as a 60i signal by dividing each frame into two fields. This allows your 24p and 30p scan footage to be played back or fed to an editing suite using the thousands of units of Sony HDV equipment already in use throughout the world. Leading manufacturers are scheduled to release nonlinear editing software compatible with this 24p scan mode. These nonlinear software will be able to detect the 2:3 sequence and remove the 2:3 properly. This way, the editor will be able to create a 24p project, edit precisely at 24fps (23.98 progressive frames per second) throughout the process, and output the final master as:
The HVR-DR60 hard disk drive can be used with existing HDV/DVCAM camcorders equipped with an i.LINK interface such as the HVR-Z1U, HVR-A1U and DSR-PD170P. However, use with the HVR-V1U offers unique features only available in this combination. Checking the operational status on the HVR-V1U On the LCD and VF of the HVR-V1U, you can easily check the operational status of the HVR-DR60 (connection, rec status, battery level, remaining recording time, recording folder name, etc.). This keeps you aware of both the camcorder and hard drive status without taking your eyes away from what you’re shooting. Tapeless recording with the HVR-V1U The HVR-DR60 hard disk drive can synchronize with the record command that is outputted from the camcorder. The HVR-V1U differs from its predecessor in that it can send a record signal with out the presence of a tape inserted. Thus tape-less, "Hybrid recording" is possible by connecting the HVR-V1U with the DVR-DR60. Maximizing the efficiency of non-linear editing
Via a simple i.LINK connection, the HVR-DR60 Hard Disk Recording Unit allows recording of a compatible HDV1080i stream from an HDV camcorder, or a DV stream from a DVCAM camcorder. The 1.8-inch internal HDD offers a large capacity of 60GB, which translates into an impressive approximately 270 minutes (4.5 hours) for both HDV and DVCAM recordings. The HDV1080i stream is recorded as native HDV files (.M2T), while DV stream is recorded as AVI files (.AVI :DV Type1). When connected to a PC, the HVR-DR60 is recognized as a standard external drive, so you can immediately access and edit the recorded footage just as any typical video file. This saves the time previously required for digitizing material from the tape to PC -- time that could otherwise be spent for more creative and productive editing tasks. Many NLE programs will be able to access files and control the HVR-DR60 hard disk drive via the i.LINK connector. With compatible programs, the HVR-DR60 hard disk drive will behave as a VTR, but with a random access file structure which will allow immediate access to clips on the disk.
Using the hybrid recording function of the HVR-V1U camcorder, in which video and audio material is recorded simultaneously to the hard disk and tape, you can be assured that you won’t lose an important shot. In the rare case that either the tape device or hard disk fails, you will always have a backup. The hybrid function also facilitates archiving operations of your all-important source footage -- which in most cases do not allow for reshoots. After a shoot, immediately archive your source tape and use the HVR-DR60 material as your work footage. Unlike camcorders using low-capacity recording media, there is no need to invest the time and effort in copying the original data to a separate high-capacity medium. Just reformat the HVR-DR60 and you are ready to go on your next assignment. Same batteries that power your camcorder The last thing you want to worry about on location is using different types of batteries. With the HVR-DR60 hard disc drive you can use the same InfoLithium L Series batteries that are used for the HVR-V1U, HVR-Z1U and DSR-PD170 camcorders. Using the smallest capacity NP-F570 battery, the HVR-DR60 operating time is approximately 270 minutes (4.5 hours), and with a high-capacity NP-F970 unit, this increases to approximately 810 minutes (13.5 hours). Long operating hours are possible with the batteries that Sony HDV users already have at hand.
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- A sequence of still images at 24 fps, for film out
- A 23.98 YUV (uncompressed) HD file, for output to CineAlta products
- A 23.98 SD MPEG2 file, for the highest quality DVD mastering possible
- A 60i HDV file (2:3 added back in), for creating an HDV edit master
- A 60i YUV (2:3 added back in, uncompressed) HD or SD file, for outputting to Digital Betacam or HDCAM for broadcast
High-resolution 1080 progressive scan Thanks to the 3 ClearVid CMOS Sensor and Enhanced Imaging Processor technology, the HVR-V1U supports 24p (progressive) scan, the frame rate of film and 30p (progressive) scan modes, in addition to typical 60i. The signals generated by the 3 ClearVid CMOS sensor are processed in the progressive domain as 1920 x 1080p signals, allowing high-resolution progressive footage to be captured. Devices Enhanced imaging processor This special imaging processor in the HVR-V1U has been developed to bring out the full power of the 3 ClearVid CMOS sensor by handling the video signal output in 1920x1080p and 4:2:2 color space. Its unique signal processing separates the image data into its texture and brightness components and processes these independently. This makes it possible to reproduce images with a high level of clarity, from the very darkest to brightest areas of the image. The signals from the four surrounding photodiodes are used to reproduce one more signal with the Enhanced Imaging Processor technology.
Carl Zeiss Vario-Sonnar T lens with extra-low dispersion glass The HVR-V1U camcorder is equipped with a high-quality Carl Zeiss Vario-Sonnar T lens. Featuring a 62mm filter diameter, this lens offers a multilayer coating, extra-low dispersion glass, aspherical glass and excellent spectral characteristics that result in reduction of chromatic aberration.
20x optical lens and wide conversion lens The HVR-V1U camcorder’s built-in 20x optical zoom lens enables long-range shots of sports events or wild animals with the stunning visual impact of HD images. Moreover, the digital extender increases the zoom ratio to approximately 30x. The optional VCL-HG0868K 0.8x wide conversion lens uses the bayonet mount system for instant attachment or detachment. Combining these lens features, you can effortlessly capture close-up or wide-angle shots as your video production requires. 3 ClearVid CMOS sensor The ClearVid CMOS sensor has been developed using the most advanced technologies in the semiconductor industry. Thanks to the unique grid arrangement of the photo diode sensors, in which each is rotated by 45 degrees, sensor resolution has been optimized while maximizing the photosensitive surface area. Combining this imaging system with its associated Enhanced Imaging Processor technology, has enabled the use of a sophisticated interpolation scheme original to Sony and entirely different from conventional spatial offset techniques. The 3 ClearVid CMOS sensor system is the core element enabling the 1920x1080p video signals. Also, unlike CCD sensors, there is no vertical smear when shooting high-intensity subjects, which further reduces shooting condition constraints. Wide dynamic range Features like shadowed faces and overbright hair are clear and natural-looking. Even with mixed dark and bright areas in the same shot, the whole picture appears natural thanks to the wide dynamic range. With HVR-DR60 (not included)
Small size and perfect balance The HVR-DR60 hard disk drive measures just 79 x 44 x 100 millimeters (W x H x L) in size, and weighs only 227 grams (excluding battery). Using the supplied shoe adapter, the unit can be mounted on the cold shoe of the camcorder. Also, by use of the optional bracket VCT-1BP, it can be mounted on the rear of the camcorder, where it will not affect the mobility of the compact camcorder. HDD Smart Protection Three advanced technologies are used for reliable recording performance of the HVR-DR60:
- Rubber shock absorbers hold the HDD unit in place, preventing external shock being transmitted when the HVR-DR60 chassis is subject to impact.
- A 3G sensor detects gravitational acceleration in three dimensions, so however the HVR-DR60 may be oriented, the sensor can detect if it has been dropped -- in which case power to the HDD is shut off and the recording heads are retracted from the disk platters, pausing read/write operations. This protects the HDD from being damaged when the unit is accidentally dropped and subject to strong impact.
- The third feature is a buffer memory, capable of storing approximately 14 seconds of video and audio footage. Recordings are made by first writing the data to the buffer, and then writing the buffer data to the disk platters. Consequently, if the 3G sensor temporarily interrupts disk writes, video footage is not lost.
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DSLR and HDV video recording
High-definition video is video of higher resolution and quality than standard-definition. While there is no standardized meaning for high-definition, generally any video image with more than 480 horizontal lines (North America) or 576 lines (Europe) is considered high-definition. 720 scan lines is generally the minimum even though the majority of systems greatly exceed that. Images of standard resolution captured at rates faster than normal (60 frames/second North America, 50 fps Europe), by a high-speed camera may be considered high-definition in some contexts. Television series' shot on high-definition video are made to look as if they have been shot on film, a technique which is often known as filmizing.
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