12-21-2009, 06:46 AM
My experience is that source material with an original aspect ratio (OAR) of 4:3 that is broadcast in HD will not scale to fill the screen.
An HD signal must be encoded at one of two predefined resolutions (720 or 1040). When 4:3 OAR material (that is, by design, at a lower resolution than either of the two used for HDTV) is encoded for HD broadcast, black bars are added on the side prior to encoding; the bars become part of the encoded signal. When the TV shows the bars, it is faithfully decoding the signal as it was broadcast.
An HD signal must be encoded at one of two predefined resolutions (720 or 1040). When 4:3 OAR material (that is, by design, at a lower resolution than either of the two used for HDTV) is encoded for HD broadcast, black bars are added on the side prior to encoding; the bars become part of the encoded signal. When the TV shows the bars, it is faithfully decoding the signal as it was broadcast.