@item merge, 0
Move odd frames into the upper field, even into the lower field,
generating a double height frame at half frame rate.
+@example
+ ------> time
+Input:
+Frame 1 Frame 2 Frame 3 Frame 4
+
+11111 22222 33333 44444
+11111 22222 33333 44444
+11111 22222 33333 44444
+11111 22222 33333 44444
+
+Output:
+11111 33333
+22222 44444
+11111 33333
+22222 44444
+11111 33333
+22222 44444
+11111 33333
+22222 44444
+@end example
@item drop_odd, 1
Only output even frames, odd frames are dropped, generating a frame with
unchanged height at half frame rate.
+@example
+ ------> time
+Input:
+Frame 1 Frame 2 Frame 3 Frame 4
+
+11111 22222 33333 44444
+11111 22222 33333 44444
+11111 22222 33333 44444
+11111 22222 33333 44444
+
+Output:
+ 22222 44444
+ 22222 44444
+ 22222 44444
+ 22222 44444
+@end example
+
@item drop_even, 2
Only output odd frames, even frames are dropped, generating a frame with
unchanged height at half frame rate.
+@example
+ ------> time
+Input:
+Frame 1 Frame 2 Frame 3 Frame 4
+
+11111 22222 33333 44444
+11111 22222 33333 44444
+11111 22222 33333 44444
+11111 22222 33333 44444
+
+Output:
+11111 33333
+11111 33333
+11111 33333
+11111 33333
+@end example
+
@item pad, 3
Expand each frame to full height, but pad alternate lines with black,
generating a frame with double height at the same input frame rate.
+@example
+ ------> time
+Input:
+Frame 1 Frame 2 Frame 3 Frame 4
+
+11111 22222 33333 44444
+11111 22222 33333 44444
+11111 22222 33333 44444
+11111 22222 33333 44444
+
+Output:
+11111 ..... 33333 .....
+..... 22222 ..... 44444
+11111 ..... 33333 .....
+..... 22222 ..... 44444
+11111 ..... 33333 .....
+..... 22222 ..... 44444
+11111 ..... 33333 .....
+..... 22222 ..... 44444
+@end example
+
+
@item interleave_top, 4
Interleave the upper field from odd frames with the lower field from
even frames, generating a frame with unchanged height at half frame rate.
+@example
+ ------> time
+Input:
+Frame 1 Frame 2 Frame 3 Frame 4
+
+11111<- 22222 33333<- 44444
+11111 22222<- 33333 44444<-
+11111<- 22222 33333<- 44444
+11111 22222<- 33333 44444<-
+
+Output:
+11111 33333
+22222 44444
+11111 33333
+22222 44444
+@end example
+
+
@item interleave_bottom, 5
Interleave the lower field from odd frames with the upper field from
even frames, generating a frame with unchanged height at half frame rate.
+@example
+ ------> time
+Input:
+Frame 1 Frame 2 Frame 3 Frame 4
+
+11111 22222<- 33333 44444<-
+11111<- 22222 33333<- 44444
+11111 22222<- 33333 44444<-
+11111<- 22222 33333<- 44444
+
+Output:
+22222 44444
+11111 33333
+22222 44444
+11111 33333
+@end example
+
+
@item interlacex2, 6
Double frame rate with unchanged height. Frames are inserted each
containing the second temporal field from the previous input frame and
the first temporal field from the next input frame. This mode relies on
the top_field_first flag. Useful for interlaced video displays with no
field synchronisation.
+
+@example
+ ------> time
+Input:
+Frame 1 Frame 2 Frame 3 Frame 4
+
+11111 22222 33333 44444
+ 11111 22222 33333 44444
+11111 22222 33333 44444
+ 11111 22222 33333 44444
+
+Output:
+11111 22222 22222 33333 33333 44444 44444
+ 11111 11111 22222 22222 33333 33333 44444
+11111 22222 22222 33333 33333 44444 44444
+ 11111 11111 22222 22222 33333 33333 44444
+@end example
+
+
@end table
Numeric values are deprecated but are accepted for backward