Monitor Functionality

[This is preliminary documentation and subject to change.]

Monitors for a broadcast client should have the following key attributes:

• Support for the minimum resolution, currently 640 x 480. However, 800 x 600 resolution is recommended. Typical satellite digital broadcasters transmit main level and main profile MPEG-2 — the middle level of the five possible levels of MPEG-2 encoding for video data. That transmission level translates into 720 x 480 x 30 frames per second for NTSC. For PAL, this level translates into 720 x 576 x 25 frames per second. As a result of this transmission type, display decimation occurs at 640 x 480 resolution, which is why 800 x 600 resolution is strongly recommended.
• Support for color gamma suitable for display of television and computer data. Diverting an MPEG stream to a computer monitor can cause color problems. These problems occur because the MPEG stream is encoded into an abstract color space, then decoded and sent to a computer monitor with a different, possibly greater color gamma than an NTSC display device.
• Picture tube that is ideal for both computers and televisions. Such a picture tube has high luminance, analog super Video Graphics Array (SVGA) inputs, medium phosphor persistence, and a progressive scan of 60 hertz.
• Good corner convergence.
• Large screen size. For an optimal viewing experience, it is recommended that OEMs build large-screen monitors for Broadcast Architecture, 31 or 33 inches in size measured on the diagonal. However, the broadcast functionality works on any size computer monitor, leaving the ultimate configuration up to the OEMs.
• Refresh rate of 60 hertz, or an integral multiple of 60 hertz, for any mode in which video is displayed. Most source video, such as NTSC or MPEG-2 video and film, is created or adjusted through temporal rescaling at a 3:2 ratio. This adjustment is performed expressly for 60 hertz television monitors. Further rescaling to other refresh rates, such as 72 hertz, introduces unacceptable motion artifacts, such as nonlinear screen motion. By using a refresh rate of 60 hertz or a multiple thereof, the monitor can be balanced with the monitor phosphor.

  For a flicker-free viewing experience, a medium-persistence phosphor should be used instead of a short-persistence phosphor. If the refresh rate is fixed at 120 hertz, the standard computer-monitor phosphors can be used.