Overview of High Definition Video
High definition video is a widescreen (16:9) format (as opposed to standard definition television which is a 4:3 aspect ratio) and offers extraordinary clarity that has created great excitement in the broadcast industry and with consumers who enjoy viewing high quality television. If you are new to HD video editing, one should be aware of the technical considerations when working with HD footage, such as resolution, scanning, frame rate, not to mention the computing power, hardware and software required to edit HD files. Ultimately the end use of your footage will dictate the capture, editing and export parameters which will best suit your needs and audience, whether delivered on feature film, broadcast television, DVD, World Wide Web or mobile devices. Royaltyfreestore.com offers royalty-free stock footage to help meet the needs of video professionals worldwide.
High Definition
Full HD resolution is 1920 x 1080 and is currently mostly broadcast in interlaced format. It can also be progressive. HD is a 16:9 aspect ratio but can be downcoverted to the standard definition 4:3 aspect ratio with an HD editing software program. Full resolution HD files are massive and require extreme computing power and storage capability and a broadcast pipe wide enough to handle the full resolution data stream not to mention a television set that is capable of displaying full resolution HD.
Currently, only the most expensive, very large HD TVs can actually display full resolution HD, so if you are a consumer check the display resolution and your wallet before you buy an HD TV. Not all television networks broadcast in the same resolution, some broadcast at full HD resolution, i.e., 1920 x 1080 interlaced and others choose to broadcast in 1280 x 720 progressive which is still high quality video but isn't as data intensive as full res HD. Progressive HD is non-interlaced.
The good news is HDTVs include software to auto scale the broadcast resolution to fit your HDTV screen and most come with remotes will allow you to manually toggle between widescreen and 4:3 aspect ratios allowing more optimal viewing of the varying broadcast resolutions while we transition from SD to HD in the next few years.
HDVTM
At the present time, due to massive file sizes, full resolution HD cannot fit on mini-dv tape widely used by videographers hence the inception of the HDV format. HDV's native 1440 x 1080 resolution can fit on a mini-dv utilizing MPEG-2 Long-GOP compression, the same compression method that many networks use to broadcast HD. Fortunately, professonal editing tools now facilitate mixing a variety of HD resolutions on the same timeline. To learn more about the HDV format, view the HDV Specification.pdf. The HDV format is gaining wide support by major industry players. To learn more about who is supporting the HDV format, visit http://www.hdv-info.org. Because HDV video uses rectangular pixels it can be upscaled to full HD resolution. HD CAMs and HDV cameras both record HD at full resolution and compress it to tape at 1440 x 1080i resolution, however the bit rate of an HD Cam is a bit higher than HDV cameras.
Progressive vs. Interlaced
HD and HDV formats offer two methods of scanning based upon ATSC standards, ie., interlaced or progressive. You may see HD video denoted as 1920 x 1080i or 1080p. 1920 refers to the horizontal width of the image. 1080 refers to the number of lines of scanned video per inch that make up the vertical screen resolution. i refers to the video as an interlaced format, where the image is composed of alternating lines of resolution that when broacast paint on screen as a complete image. The letter "p" stands for progressive which indicates the video is a series of complete images being broadcast in progression, much like individual frames of an animation. You'll also see HD resolution denoted at 1280 x 720p. 720p refers to the number of vertical lines that are scanned by the receiving TV during broadcast. Since many television networks broadcast HD at 1280 x 720p, many affordable HD TVs are manufactured at this screen resolution.
HD in Feature Films
Full resolution HD is ideal for feature film productions. The HD video can be converted to film and displayed in theatres using existing projectors. As theatres switch to digital projection the use of film in theatres will eventually become obsolete and replaced with digital video (as predicted by George Lucas who actually drove the design of Sony's HD cameras). Although this author did read recently that George Lucas is planning to produce more television programming than film going forward since more people are preferring HD TV viewing rather than to going to a theatre. (Which makes sense, because film stock is expensive and HD digital video production is so much faster, easier and offers great quality).
If however you intend to port your HD video into theatrical release and transcode it to film, for optimum quality its best to use HD footage sourced from a high bit rate camera. Before shooting video that you hope to port to feature film, be sure to record in the desired frame rate, as the frame rate for film is different than broadcast video and there are technical considerations involving frame rate and color pulldown that you need to understand in order for a quality conversion from HD video to film to happen. So be smart and do your homework before attempting to shoot the next blockbuster for theatrical release.
We hope this article has been helpful to you, but please be aware as a video professional or consumer there may be other technical considerations you may wish to take into consideration for your particular project needs or HD television set purchase that are not detailed here. Always talk to your clients before editing your video to ascertain their desired resolution and frame rate for the target media whether it is a feature film, broadcast television, internet video or DVD distribution.
