Patent ID: 7142246

Claim:
An apparatus for producing an output stream of de-interlaced image frames from an incoming stream of interlaced image fields, the interlaced image fields including complementary pairs of fields which together comprise a frame, comprising: an input buffer including field buffers storing the incoming stream of interlaced image fields; field match detection logic, coupled to the input buffer, to assert a match signal upon detection of matching fields in field buffers storing fields from the incoming stream separated by a current field and; de-interlace logic, coupled to the input buffer, to read complementary pairs of fields from the input buffer, and to output de-interlaced frames; and control logic, coupled to input buffer, the field match detection logic and the de-interlace logic, which causes fields from the incoming stream of interlaced fields to be written to field buffers in the input buffer, and which causes pairs of fields in the input buffer to be supplied to the de-interlace logic in a de-interlace sequence, including supplying a current field from one of the field buffers paired with a complementary field selected from one of two fields stored in adjacent field buffers to the de-interlace logic, wherein the control logic includes a state machine responsive to the field match detection logic to select the selected one of the adjacent field buffers storing the complementary field, including a first state in which a 3:2 pull down mode is not applied, a second state in which the 3:2 pull down mode is applied, and which is entered from the first state in response to assertion of the match signal for a current field, a third state in which the 3:2 pull down mode is applied, and which is entered from the second state for a next current field, a fourth state in which the 3:2 pull down mode is applied, and which is entered from the third state for a next current field, a fifth state in which the 3:2 pull down mode is applied, and which is entered from the fourth state for a next current field, and a sixth state in which the 3:2 pull down mode is applied, and which is entered from the first state for a next current field, wherein the state machine transitions from the sixth state to the first state if the match signal is not asserted for a next current field, and transitions from the sixth state to the second state if the match signal is asserted for a next current field.