Q and A about HDV
HDV Specification
Advantages of HDV

Q Isn't picture quality deterioration such as block noise and errors usually a concern with MPEG-2?
A Since a bit rate after compression of 25 Mbps has been achieved, the format allows very good picture quality for recording and playback.

Q What companies support the HDV standard?
A  The HDV standard was established by four companies: Canon Inc., Sharp Corporation, Sony Corporation, and the Victor Company of Japan, Limited. Many companies including most of the non-linear software manufacturers have expressed their support for the HDV standard. For the latest list of companies that support this format visit http://www.hdv-info.org

Q What is the audio compression method for HDV?
A The audio compression format is MPEG-1 Audio Layer II. This format can compress and record a signal with a sampling frequency of 48 kHz and quantization of 16 bits, at a bit rate of 384 Kbps

Q Why are there so many companies supporting HDV?
A This is because it is a based on the global DV standard, and the same DV mechanisms can be used for HDV. Moreover, since it employs the broadcast standard for image compression, MPEG-2, it is possible to connect HDV devices with TVs and personal computers.

Q Which has better sound quality, HDV or DV?
A With DV's 16-bit 2-ch mode sound and HDV's audio recording, DV has better quality sound for the parts where compression is not carried out. However, since HDV uses a very high bit rate (384 Kbps) for sound compression, the sound quality is almost on par with uncompressed audio.

Q What kind of media is used for HDV?
A Conventional DV tapes are used for recording in HDV.

Q Is the HDV sound quality comparable to a music CD?
A Since HDV audio is compressed, theoretically it is inferior to CD sound quality. However, as mentioned above, by securing a high bit rate after compression, the sound quality is almost on par with that of a CD.

Q How long is the HDV recording time?
A It is the same as DV recording time. Also, with the HDV 1080i specification, there is no long- playing mode.

Q In the future, will the DV standard disappear and the HDV standard become mainstream?
A Along with the widespread adoption of HD broadcasting and HDTVs, it is expected that the HDV standard will soon become the norm. However, DV is currently the mainstream as far as price and the popularity of DV displays are concerned. Nevertheless, there will soon be more models of HDV camcorders on the market, and when the prices come down, HDV will likely replace DV as the main standard.

Q How is it possible that the large HD video data quantity of HDV can be recorded in the same running time as the DV standard on DV tape?
A Recording is possible in the same running time because MPEG-2 is used. MPEG-2 is a compression system that can realize high resolution even at a low bit rate by using information on differences between frames.

Q What is the difference between 1080i and 720p?
A The 720p specification employs progressive scanning with 720 vertical scanning lines (effective scanning lines), and the 1080i specification employs interlace scanning with 1,080 lines.

Q What is the difference between HDV and DV? Which has better picture quality? HDV and DV have different image compression and tape recording methods. Since HDV was developed in order to record and play back high resolution HDTV video, HDV has higher resolution from the standpoint of the number of  pixels.

Q Why are there two specifications (1080i and 720p) for the HDV standard?
A This is to enable the development of products that meet different HD infrastructures around the world.

Q What is the HDV video compression method?
A HDV uses MPEG-2 compression, and the bit rate after compression for the 1080i specification is 25 Mbps.

Q Which has better picture quality, HDV 1080i or HDV 720p?
A The picture quality depends on the specifications of the product. Select the specification that best meets your needs.

Q Is it possible to record HDV and DV alternately on the same DV tape?
A It is possible under the standard, but it depends on whether the manufactures will develop their products to allow mixed recording on the same tape.

Q How does the HDV error correction method differ between 1080i and 720p?
A The main difference is the correction coding ratio, and the mechanism for error correction over multiple tracks.

Q Can an HDV camcorder also record in DV?
This depends on the product specifications.

Playback and editing

Q If I play a DV tape containing an HDV recording on a regular DV camcorder rather than an HDV camcorder, and then output the signal to a TV, will it still be HD output?
A Tapes with HDV recordings are only guaranteed for playback on HDV camcorders. If you do try to do this anyway, either the video and sound will not play back, or depending on the model, it will determine that it is an HDV recording and warn you not to record over it.

Q Can I upload HDV data to my computer and edit it? Is it possible to edit both the video and audio just like with DV data?
A This is possible if you have an HDV application software on your computer. The type of editing will depend on your software.

Q Can tapes recorded with the 1080i specification be played back on a 720p-specification camcorder? Or vice versa?
A It may not always be possible for a 720p camcorder to play back a tape recorded in the 1080i specification, and vice versa. Compatibility depends on the actual specifications of the product.

Q Can I upload HDV data to my computer and then save it on a DVD disc?
A If your HDV application software allows you to convert the data to SD, you can save it as a DVD video. Also, you can save it on a DVD data disk, which is the same concept as data backup. However, in this case it will not be compatible for use on a DVD player.

Q If I play an HDV recorded tape on an HDV camcorder, and then connect it to a non-HD TV and output the signal, will it provide better or worse picture quality than playing a DV recorded tape?
A This depends on the product specifications.

Q After uploading HDV data to my PC and editing it, can I then write the data to a DV tape using the HDV or DV standard?
A Either is possible if your HDV application software permits it.

A i.LINK(IEEE1394) connection is recommended.

Q What are the necessary PC specs to allow for uploading and editing of HDV data?
A Pentium 4 3.06 GHz or higher RAM: 256 MB or higher (1 GB or more is recommended) HDD: UltraATA100 i.LINK terminal as standard equipment Display: XGA or higher Video memory: 32 MB or higher Software: Windows XP SP2 or higher * The above specifications are provided as a guideline. Be sure to also check the specs required by the application software.

A This is possible using an HDV application software on your PC. The file format will depend on your software.

A If the data is uploaded in MPEG-2 format without conversion, the file will be about the same size as a DV file of the same running time. A ten minute video is about 2 GB.

Glossary

The number "720" indicates the number of scanning lines, and "p" indicates progressive scanning.

This is the name of the HDTV service developed by Japan's NHK. Digital HDTV is also called Digital Hi-Vision in Japan.

The number "1080" indicates the number of scanning lines, and "i" indicates interlace scanning.

This is a standard for connecting computers to peripheral equipment. The name i.LINK is a nickname for IEEE 1394 developed by Sony. It allows up to 63 devices to be linked together, and has a maximum transmission speed of 400 Mbps. It has the advantage of providing power through the connection cable, as well as a hot plug (able to connect or disconnect without cutting the power to the device). It is used to connect with DV camcorders. In the DV standard i.LINK is called a DV terminal.

The aspect ratio is the ratio of the screen width to height. Conventional TVs have an aspect ratio of 4:3, while HDTV has a wider ratio of 16:9.

MPEG-2 is the video standard, and Dolby AC-3 is the audio standard.

Interlace scanning

Interlace scanning is mainly used for TV broadcasts. The reason for this is that if the image continuity is high and interlace scanning can provide smoother movement as mentioned previously, while the frequency range is limited, it is adopted since the reduced resolution is not very noticeable.

Compression 
A generic term for any technology that enables data to take up less space. Compression can be applied to data files, images, audio, or video. Lossless compression is used for software, text files, or any application where all the original bits must be retained when a file is decompressed. Lossy compression is most often used for digital audio, video, or images, where some of the original data can be sacrificed to reduce large file sizes. Lossy compression degrades the quality of the original data somewhat. But the smaller file size makes the data much easier to store and faster to transmit.

Composite Video 
A type of video signal in which all the necessary video information is combined into one signal. This is the type of signal used for broadcast TV in the United States. Most computer monitors use RGB video, in which the red, blue, and green signals are sent separately to produce a sharper image

For all of these standards MPEG-2 is used as the video coding, while MPEG-2 Advanced Audio Codec (AAC) is used for the audio coding. It has the advantage of allowing the use of common receivers regardless of the transmission format, as it is offered together with services such as EPG and data broadcasting.

These terminals transmit each of the three video chrominance difference signals: Y (luminance signal), R-Y (signal of red signal minus luminance), and B-Y (signal of blue signal minus luminance), through separate cables. Since three cables are used, the terminals are also divided into three.

MPEG means "Moving Picture Expert Group", and is the name of the organization that developed the standard for recording video and audio as digital data. It also indicates the video and audio digitalization standard created by the same organization. MPEG-2 is one of the standards developed by this organization, and is used in various fields including DVDs and digital broadcasting.

This is broadcasting through digitized cable signals. The digital cable TV standard includes ISDB and DVB.

This stands for "Multiple Sub-Nyquist-Sampling Encoding", which is an HDTV broadcasting system based on an analog format developed by the NHK Science & Technical Research Laboratories (NHK STRL) in Japan. This format was a precursor to today's HDTV system.

This indicates digital broadcasting from man-made satellites orbiting the earth. The digital satellite broadcasting standards include ISDB and DVB.

This is the SDTV broadcasting format established by the "National Television Systems Committee" in the US. It uses interlace scanning with 525 scanning lines and a frame frequency of 30 Hz.

This is a terminal that can transmit the three chrominance difference signals that make up the video signal: Y (luminance signal), R-Y (signal of red signal minus luminance signal), and B-Y (signal of blue signal minus luminance signal), in one cable. Its name comes from the fact that the shape of the terminal looks like the letter  "D." The types of terminals include the D1 terminal for 480i, the D2 terminal for 480p and 480i, the D3 terminal for 1080i, 480p, and 480i, and the D4 terminal for 720p, 1080i, 480p, and 480i. In order to transmit the HDTV video signal, the devices at both ends need to have D3 or D4 terminals.

This is the number of scanning lines that actually produce the image on the screen.

PAL is an abbreviation for "Phase Alternation by Line", which is an SDTV broadcasting format developed in the former West Germany. It uses interlace scanning with 625 scanning lines and a phase frequency of 25 Hz.

This stands for "Digital Video Broadcasting", and is the digital TV broadcast format developed by the DVB project established jointly by European manufacturers. It includes standards for terrestrial, satellite and other forms of transmission, and the main standards include DVB-T for terrestrial digital, DVB-S for satellite digital, and DVB-C for cable digital broadcasting. MPEG-2 is used as the standard for video coding, and MPEG-2 Layer I and II are used for the audio coding standard. DVB is not just for HDTV, but also provides a lot of services that use the data reduction benefits of digitalization to create multiple channels.

Progressive scanning is a display method where lines are scanned in order from the first to the last, and one image is produced with one scan. It is also called non-interlace scanning. For example, if there are 480 scanning lines, the lines are scanned in order from the first to the 480th line. The advantage of progressive scanning is that a picture without flickering can be achieved.

This is the standard for videocassette recorders, which can record images and sound in the digital format on special compact tapes. It has the advantages of good quality through recording in the digital format, and high compatibility with computers.

This is the connector used for composite video / audio, and component terminals. It was developed by RCA in the US.

A field indicates one image under the interlace system. With interlace scanning, one image is one field, that is to say, there are two fields in one frame.

Resolution indicates the level of the picture quality. When the resolution is high, then the picture clarity is also high.

Field frequency indicates the number of fields produced in one second.

Scanning

Scanning involves the movement of light points to produce TV images. TV pictures are produced by the movement of points of light, which create afterimages. The points of light move from the left to the right side of the screen's top row, and then repeat this movement in the next row from left to right. Once the right side of the bottom row is reached, one image has been completed.

A frame is an image unit where all the scanning lines are scanned. Since one image is produced with one scan under progressive scanning, one frame equals one image. However, with interlace scanning, one frame equals two images, as two images are produced with a single scan.

This is the line created by the points of light moving from left to right across the TV screen. The larger the number of scanning lines, the sharper the picture.

Frame frequency is the number of frames produced in one second.

SDTV stands for "Standard-definition Television", indicating the usual TV picture quality before the development of HDTV. It is a TV broadcasting standard with an aspect ratio of 4:3.

HDTV stands for "High-definition Television", which is a new TV technology that provides more realistic images than conventional televisions. In order to increase the feeling of realism, a high level of resolution needed for larger screen TVs has been achieved, along with the adoption of a 16:9 aspect ratio. Furthermore, HDTV is a next-generation television broadcast standard that is a complete departure from the existing broadcast formats of NTSC, PAL, and SECAM.

This is the SDTV broadcasting format developed in France called Sequential Couleur A Memoire (Sequential Color with Memory). It uses interlace scanning with 625 scanning lines and a frame frequency of 25 Hz.

This is the standard for studio production to allow easy international exchange of HDTV content. It establishes standards for the HDTV video signal including the number of scanning lines. All the HDTV broadcasting formats follow the studio standard so that video content can be easily exchanged from one region to another, even though the broadcasting formats differ.

This is the videocassette recorder standard that can record and play back HD (aspect ratio of 16:9) video and audio using widely available DV tapes. Since it employs the MPEG-2 compression system, it can record in the same running time as the DV standard, despite the higher resolution involved. HDV includes the 1080i specification using 1,080 effective scanning lines (interlace), and the 720p specification with 720 lines (progressive).

This is digital broadcasting from TV towers built on the ground. The terrestrial digital broadcasting standards include ISDB, DVB, and ATSC.