SMPTE 421, informally known as VC-1, is a video coding format. Most of it was initially developed as Microsoft's proprietary video format Windows Media Video 9 in 2003. With some enhancements including the development of a new Advanced Profile, it was officially approved as a SMPTE standard on April 3, 2006. It was primarily marketed as a lower-complexity competitor to the H.264/MPEG-4 AVC standard. After its development, several companies other than Microsoft asserted that they held patents that applied to the technology, including Panasonic, LG Electronics and Samsung Electronics. VC-1 is supported in the now-deprecated Microsoft Silverlight, the briefly-offered HD DVD disc format, and the Blu-ray Disc format. Format VC-1 is an evolution of the conventional block-based motion-compensated hybrid video coding design also found in H.261, MPEG-1 Part 2, H.262/MPEG-2 Part 2, H.263, and MPEG-4 Part 2. It was widely characterized as an alternative to the ITU-T and MPEG video codec standard known as H.264/MPEG-4 AVC. The Advanced Profile of VC-1 contains tools designed for coding interlaced video sequences as well as progressive scan video. The main goal of the development and standardization of the VC-1 Advanced Profile was to support interlace-optimized compression of interlaced content without first converting it to progressive scan, making it more attractive to broadcast and video industry professionals using the 1080i format. Both HD DVD and Blu-ray Disc adopted VC-1 as a supported video format, meaning their video playback devices are required be capable of decoding and playing video-content compressed using VC-1. Windows Vista partially supports HD DVD playback by including the VC-1 decoder and some related components needed for playback of VC-1 encoded HD DVD movies. Microsoft designated VC-1 as the Xbox 360 video game console's official video format, and game developers could use VC-1 for full motion video included with games. By means of an October 31, 2006 update, all formats of Windows Media Video could be played on the Xbox 360 from a disc, USB storage device, or streaming from a PC via Windows Media Connect/Windows Media Player 11. VC-1 is supported in the PlayStation 3 console and the FFmpeg project also includes a VC-1 decoder. On August 24, 2012, the Raspberry Pi Foundation announced hardware decoding support for VC-1. Microsoft codec implementations The VC-1 codec specification has so far been implemented by Microsoft in the form of three codecs, each identified with a unique four character code. WMV3 The Simple and