HDV is a format for recording high-definition video on DV (digital video) 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. HDV and HDV logo are trademarks of JVC and Sony. In HDV, video and audio are encoded in digital form, using lossy interframe compression. Video is encoded with the H.262/MPEG-s Part 2 compression scheme. Stereo audio is encoded with the MPEG-1 Layer 2 compression scheme. The compressed audio and video are multiplexed into a MPEG-2 transport stream, which is typically recorded onto magnetic tape, but can also be stored in a computer file allowing for convenient file-sharing for reference, archiving filmed material, editing (including the addition of metadata such as subtitles and closed captioning) and transcription.
Two major versions of HDV are HDV 720p and HDV 1080i. The former is used by JVC and is informally known as HDV1. The latter is preferred by Sony and Canon and is sometimes referred to as HDV2. HDV 720p format allows recording high definition video (HDV-HD) as well as progressive-scan standard definition video (HDV-SD). HDV-HD closely matches broadcast 720p progressive scan video standard in terms of scanning type, frame size, aspect ratio and data rate. Early HDV 720p camcorders could shoot only at 24, 25 and 30 frames per second. Later models offer both film-like (24p, 25p, 30p) and reality-like (50p, 60p) frame rates.
Sony adapted HDV, originally conceived as progressive-scan format by JVC, to interlaced video. Interlaced video has been a useful compromise for decades due to its ability to display motion smoothly while reducing recording and transmission bandwidth. Interlaced video is still being used in acquisition and broadcast, but interlaced display devices are being phased out. All modern computer monitors use progressive scanning as well.
Because HDV video is recorded in digital form, original content can be copied onto another tape or captured to a computer for editing without quality degradation. Depending on capturing software and computer’s file system, either a whole tape is captured into one contiguous file, or the video is split in smaller 4-GB or 2-GB segments, or a separate file is created for each take. The way files are named depends on capturing software. Some systems convert HDV video into proprietary intermediate format on the fly while capturing, so original format is not preserved.
HDV footage can be natively edited by most non-linear editors, with real-time playback being possible on modern mainstream personal computers. Slower computers may exhibit reduced performance compared to other formats such as DV because of high resolution and interframe compression of HDV video.