Limiter

Revision as of 17:02, 9 May 2013

Limiter(clip clip [, int min_luma] [, int max_luma] [, int min_chroma] [, int max_chroma] [, string show])

This filter is present in v2.5. The standard known as CCIR-601 defines the range of pixel values considered legal for presenting on a TV. These ranges are 16-235 for the luma component and 16-240 for the chroma component.

Pixels outside this range are known to cause problems with some TV sets, and thus it is best to remove them before encoding if that is your intended display device. By default this filter clips (or "clamps") pixels under 16 to 16 and over 235 (or 240) to 235 (or 240).

Prior to v2.53 the (incorrect) default value was 236. Use Limiter(16, 235, 16, 240) for CCIR-601 compliant digital video.

In v2.56, an option show is added (works only for YUY2, YV12 and since v2.60 for YV24). If set, it colors the pixels outside the specified [min_luma,max_luma] or [min_chroma,max_chroma] range. show can be "luma" (shows out of bound luma), "luma_grey" (shows out of bound luma and makes the remaining pixels grey), "chroma" (shows out of bound chroma), "chroma_grey" (shows out of bound chroma and makes the remaining pixels grey). The coloring is done as follows:

YUY2 (chroma shared between two horizontal pixels p1 and p2: Y1UY2V): j,k=1,2
YV24 (no chroma shared): j,k=1
YV12 (chroma shared between 2x2 pixels Y11UY12V; Y21UY22V): j,k=11,12,21,22

Changes