Slide 11 of 27
Notes:
Video conferencing is intended primarily for subjects of the “talking heads” variety. Typically the codecs employed do not do a good job of compressing video where large changes occur from frame to frame.
In general, the smaller the frame size and the slower the frame rate the fewer bits are needed to encode an image.
H.32x standards for frame rates are for a minimum of 7.5 frames per second (fps), up to a maximum of 30 fps.
H.32x standards for frame sizes are for a minimum of QCIF, to a maximum of CIF. Larger frame sizes can be used, but are not required for meeting the standards.
MPEG video is typically CIF size, with pixel replication and smoothing performed to display a final image of 4CIF size.
H.263 is a very efficient, but high compute level codec. It provides a better image on a per-bit basis than its predecessor, H.261.
It is important to have the subject well lit. Backlighting or very low light levels are typical problems in video conferencing.
Camera quality makes a considerable difference in the quality of the video recorded. Garbage in, garbage out.
