Re: YUV clamped or unclamped ?
"Timothy B. Terriberry" <[email protected]> Wed, 14 Apr 2010 20:36:11 -0400
| Newsgroups | gmane.comp.multimedia.ogg.theora.devel |
|---|---|
| Message-ID | <[email protected]> |
salsaman wrote: > Hi, > can somebody confirm whether theora uses clamped (16 - 235, 16 - 240) or > unclamped (0 - 255) YUV ? The specification clearly states that the former is to be used (see Section 4.3). However, there is nothing internal to the codec that enforces this. > My tests are showing that Y is always in the range 16 - 235 but the U > and V channels occasionally go above 240. The codec itself will not clamp things to these ranges, so the whole "lossy compression" thing can occasionally produce values slightly outside of them. This is normal.