Re: [FFmpeg-user] Numerical histogram output for checking typical broadcast ranges (16-235)
> I cannot explain the relevant specifications (and I > don't even know where to find them) http://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.601-7-201103-I!!PDF-E.pdf "220 (8-bit) or 877 (10-bit) quantization levels with the black level corresponding to level 16.00d and the peak white level corresponding to level 235.00d. The signal level may occasionally excurse beyond level 235.00d or below level 16.00d" Similarly for 709. P ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
Re: [FFmpeg-user] Numerical histogram output for checking typical broadcast ranges (16-235)
On 17/05/15 13:05, Carl Eugen Hoyos wrote: > Christoph Gerstbauer gmail.com> writes: > >>> do you realise that valid (specification-compliant) >>> broadcast-range video may contain values < 16 and > 235? >> >> Hello Carl, no, I don´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
Re: [FFmpeg-user] Numerical histogram output for checking typical broadcast ranges (16-235)
Christoph Gerstbauer gmail.com> writes: > > do you realise that valid (specification-compliant) > > broadcast-range video may contain values < 16 and > 235? > > Hello Carl, no, I don´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. Carl Eugen ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
Re: [FFmpeg-user] Numerical histogram output for checking typical broadcast ranges (16-235)
I am very new in using the histogram filter. (http://ffmpeg.org/ffmpeg-filters.html#histogram) Is it possible to dump the video level values from which the histogram graph is drawn into numeric values (textfile dump) to check if a video has levels inside the broadcast ranges (16-235/94-940)? Sorry if I misunderstand (and my knowledge about the question is definitely limited) but do you realise that valid (specification-compliant) broadcast-range video may contain values < 16 and > 235? Carl Eugen Hello Carl, no, I don´t. Can you explain this to me? I always thought that SD broadcast levels has to be >16 and <235. Best Regards Christoph ___ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user
