HDV is a format for recording of high-definition video on DV videocassette 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. Video and audio coding HDV video and audio are encoded in digital form, using lossy inter frame compression. Video is encoded with the H.262/MPEG-2 Part 2 compression scheme, using 8-bit chroma and luma samples with 4:2:0 chroma subsampling. Stereo audio is encoded with the MPEG-1 Layer 2 compression scheme. The compressed audio and video are multiplexed into an MPEG-2 transport stream, which is typically recorded onto magnetic tape, but can also be stored in a computer file. The data rate for both the audio and video is constant and is roughly the same as DV data rate. The relatively low video data rate can cause bit rate starvation in scenes that have much fine detail, rapid movement or other complex activity like flashing lights, and may result in visible artifacts, such as blockiness and blurring. In contrast to the video, HDV audio bitrate is relatively generous. At the coded bitrate of 384 kbit/s, MPEG-1 Layer 2 audio is regarded as perceptually lossless. Recording formats 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. The HDV 1080i defines optional progressive recording modes, and in recent publications is sometimes called HDV 1080 or 1080-line HDV as progressive 1080-line recording becomes commonplace. HDV 720p 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. Earlier 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. HDV-SD is a mode for recording progressive-scan standard definition video. Such a video is sometimes called enhanced definition video (EDTV), but is