On 17/05/15 13:05, Carl Eugen Hoyos wrote: > Christoph Gerstbauer <christophgerstbauer <at> gmail.com> writes: > >>> do you realise that valid (specification-compliant) >>> broadcast-range video may contain values < 16 and > 235? >> >> Hello Carl, no, I donĀ“t. >> Can you explain this to me? >> I always thought that SD broadcast levels has to >> be >16 and <235. > > I cannot explain the relevant specifications (and I > don't even know where to find them) to you but to the > best of my knowledge: > Just as "MPEG constant bitrate" does not mean constant > frame size, so a stream containing video frames of > different sizes is not necessarily "variable bitrate", > you cannot judge a video stream as being non-"broadcast > level" just because it contains values < 16 or > 235. >
I would say a broadcast signal could quite reasonably contain values < 16 or > 235, that is the point of such values, it allows for over/undershoot transients resulting from analogue to digital conversion, or filtering. What you could reasonably say is that a broadcast signal to Rec601 or 709 etc has its black and white points defined at those values, and that anything outside that range should only be a transient, which those specs allow to be preserved in the interests of avoiding distortion. > Carl Eugen > [..] -- Tim. Key Fingerprint 38CF DB09 3ED0 F607 8B67 6CED 0C0B FC44 8B0B FC83 _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user