A system for deriving a interlaced SDTV signal from a progressively-scanned television signal having substantially the number of active picture scanning lines in a frame as the interlaced SDTV signal has in a frame (i.e., two interlaced fields) and having a progressive scan frame rate substantially the same as the interlace field rate of the compatible standard-bandwidth television signal, said progressively-scanned television signal created by or derived from a HDTV source, and for deriving a progressively-scanned television signal from a interlaced SDTV signal, comprising:
- an encoder including:
- a low-motion signal processor receiving the progressively-scanned television signal and providing a interlaced SDTV signal having a field rate substantially the same as said progressive scan frame rate, but in which changes in the television signal active picture information do not exceed the interlaced television signal frame rate, said low-motion signal processing path including a time-domain lowpass filter,
- a high-motion signal processor receiving the progressively-scanned television signal and providing a interlaced SDTV signal having a field rate substantially the same as said progressive scan frame rate, in which changes in the interlaced television signal active picture information may exceed the interlaced television signal frame rate but do not exceed the interlaced television signal field rate,
- a motion control generator receiving the progressively-scanned television signal and providing a motion control signal, derived from differences in picture information from frame to frame of said progressively-scanned television signal, indicating the degree of motion in said progressively-scanned television signal, and
- a switch, controlled by said motion control signal, receiving the signal output of said low-motion signal processor and the signal output of said high-motion signal processor for selecting either of said signal outputs or a mixture of said signal outputs, in accordance with the degree of motion indicated by said motion signal, to produce said interlaced SDTV signal, the signal having a varying motion resolution, and
- a decoder comprising:
- a motion control generator receiving the interlaced SDTV signal and providing a motion control signal, derived from field-to-field differences, indicating the degree of motion in said interlaced SDTV signal, said motion control generator including a pattern detector providing
- a pattern YES/NO signal, where YES indicates the detection of a pseudo-film pattern and NO indicates the non-detection of a pseudo-film pattern, and
- a field merge signal, the field merge signal indicating, when the pattern YES/NO signal is in its YES condition, which pairs of interlaced fields are derived from the same pseudo-film frame,
- a low-motion signal processor, controlled by said field merge signal, receiving the interlaced SDTV signal and providing two identical progressively-scanned television signal frames from each pair of interlaced fields identified by said field merge signal,
- a high-motion signal processor receiving the interlaced SDTV signal and providing a progressively-scanned television signal having a frame rate the same as the field rate of said interlaced television signal, in which each frame is derived from at least one field of said interlaced SDTV signal,
- a switch, controlled by said motion control signal and said pattern YES/NO signal, receiving the signal output of said low-motion signal processor and the signal output of said high-motion signal processor for selecting, when the pattern YES/NO signal is in its YES condition, in accordance with the degree of motion indicated by said motion signal, one of said signal outputs or a mixture of the two signal outputs, the resulting signal having a varying motion resolution, and for selecting, when the pattern YES/NO signal is in its NO condition, the output of said high-motion signal processor, to produce said progressively-scanned television signal.