ITU-R Recommendation BT.601, more commonly known by the abbreviations Rec. 601 or BT.601 (or its former name CCIR 601), is a standard originally issued in 1982 by the CCIR (an organization, which has since been renamed as the International Telecommunication Union Radiocommunication sector) for encoding interlaced analog video signals in digital video form. It includes methods of encoding 525-line 60 Hz and 625-line 50 Hz signals, both with an active region covering 720 luminance samples and 360 chrominance samples per line. The color encoding system is known as YCbCr 4:2:2. The Rec. 601 is also used for SDTV and DVD.
The Rec. 601 video raster format has been re-used in a number of later standards, including the ISO/IEC MPEG and ITU-T H.26x compressed formats, although compressed formats for consumer applications usually use chroma subsampling reduced from the 4:2:2 sampling specified in Rec. 601 to 4:2:0.
The standard has been revised several times in its history. Its seventh edition, referred to as BT.601-7, was approved in March 2011 and was formally published in October 2011.
Background and history
In the early 1980s, digital television equipment was beginning to emerge, but each manufacturer was developing their own proprietary digital versions of existing analog standards like PAL, SECAM, and NTSC.
At an ITU meeting in 1981, CCIR Study Group 11 approved document 11/1027 describing the parameter values for a unified digital video format. This was adopted as Draft Rec. AA/11 "Encoding Parameters for Digital Television for Studios" by the CCIR Plenary Assembly in February 1982, later becoming ITU-R Rec. 601.
See also
- Digital component video
- YCbCr
- Rec. 709, the corresponding standard for high-definition television (HDTV)
- Rec. 2020, ITU-R Recommendation for ultra-high-definition television (UHDTV)
- ITU-R BT.656, ITU-R Recommendation for parallel and serial transmission formats for BT.601 video
- Pixel aspect ratio