Most current revisions of SMPTE 372M, SMPTE 424M and EBU Tech 3299 require YCbCr color space and 4:2:2 chroma subsampling for transmitting 1080p50 (nominally 2.08 Gbit/s) and 1080p60 signal. Studies from 2009 show that for digital broadcasts compressed with H.264/AVC, transmission bandwidth savings of interlaced video over fully progressive video are minimal even when using twice the frame rate; i.e., 1080p50 signal (50 progressive frames per second) actually produces the same bit rate as 1080i50 signal (25 interlaced frames or 50 sub-fields per second). In the United States, the original ATSC standards for HDTV supported 1080p video, but only at the frame rates of 23.976, 24, 25, 29.97 and 30 frames per second (colloquially known as 1080p24, 1080p25 and 1080p30). In July 2008, the ATSC standards were amended to include H.264/MPEG-4 AVC compression and 1080p at 50, 59.94 and 60 frames per second (1080p50 and 1080p60). Such frame rates require H.264/AVC "High Profile Level 4.2", while standard HDTV frame rates only require Level 4.0. This update is not expected to result in widespread availability of 1080p60 programming, since most of the existing digital receivers in use would only be able to decode the older, less-efficient MPEG-2 codec, and because there is a limited amount of bandwidth for subchannels. In Europe, 1080p25 signals have been supported by the DVB suite of broadcasting standards. The 1080p50 format is considered to be a future-proof production format and, eventually, a future broadcasting format. 1080p50 broadcasting should require the same bandwidth as 1080i50 signal and only 15–20% more than that of 720p50 signal due to increased compression efficiency, though 1080p50 production requires more bandwidth or more efficient codecs such as JPEG 2000, high-bitrate MPEG-2, or H.264/AVC and HEVC. In September 2009, ETSI and EBU, the maintainers of the DVB suite, added support for 1080p50 signal coded with MPEG-4 AVC "High Profile Level 4.2" with Scalable Video Coding extensions or VC-1 "Advanced Profile" compression; DVB also supports 1080p encoded at ATSC frame rates of 23.976, 24, 29.97, 30, 59.94 and 60.