The Advanced Television Systems Committee (ATSC) is the group that helped to develop the new digital television standard for the United States, also adopted by Canada, Mexico, and South Korea and being considered by other countries. It is intended to replace the NTSC system and produce wide screen 16:9 images up to 1920×1080 pixels in size—more than six times the display resolution of the earlier standard. However, a host of different image sizes are supported, so up to six standard-definition "virtual channels" can be carried in a single broadcast. ATSC also boasts "theater quality" audio because it uses the Dolby Digital (AC-3) format to provide "5.1" surround sound. Numerous auxiliary data services can also be provided.
ATSC coexists with the more widely used DVB standards, and ISDB being implemented in Japan. The system includes the capability to carry PAL- and SECAM-format video (576 displayable lines, 50 fields per second) along with NTSC (480 displayable lines, 60 fields per second) and film (24 frames per second). Broadcasters who use ATSC and must retain an analog signal have to broadcast on two separate channels, as the ATSC system requires use of an entire six megahertz channel. The system has been criticized as being complicated and expensive to implement and use. Many aspects of ATSC are patented, including the AC-3 audio coding, and the VSB modulation. The standards ATSC depends on are often ambiguous, one example would be the EIA-708 standard for closed captioning.