AVCHD RGB video leves

[mrduck]

Yesterday I had the occasion to look at the video leves of a avchd video and it looked strange to me (but I'm just an hobbist)

video 1 (shot in a theater) and video 2 (shot on the snow)
R and G values were almost 16/240 (with some sparks up to 255)
B values were from 0 to 255...


From what I know, a codec works with studio levels ( 15-240) or video levels (0-255)... here it seems that is using a mix

PS: snow video taken pre-hack, theater video post-hack SH settings C

 

[DaLiV]

firstly teach native colorspace ... YUV 0-255 is much wider than RGB 0-255 /there will be values that is over 255 and below 0 after conversion to RGB/ if you need to knew exact codec range - only YUV information may be taken in account ...

 

[MR Fanny]

no idea what i am looking at here but it sure does look interesting. i suggest you shoot the exact same scene one with patch and one without to help join the dots in understanding the patch.

 

[DaLiV]

you are looking to "vectroscope"/+"rgb parade" monitors for converted YUV to RGB in Sony Vegas software. and note - that not works with native YUV format, which is used in all primary video material .

+ scenes is diffirent ...

 

[mrduck]

firstly teach native colorspace ...

Please point me to some doc

YUV 0-255 is much wider than RGB 0-255 /there will be values that is over 255 and below 0 after conversion to RGB/ if you need to knew exact codec range - only YUV information may be taken in account ...

I just notices the strangess that, in totally different images, blue was 0-255 and red/green were 15-255....

 

[DaLiV]

doc's - any of MPEG technical docs, can try to start from
http://en.wikipedia.org/wiki/H.264
http://en.wikipedia.org/wiki/Chroma_subsampling
http://en.wikipedia.org/wiki/YUV

then try to calculate RGB for YUV (91,221,201) and try to understand where on RGB scales will be G and B values for that example /red on another example will move in the same way/ (however that sample YUV values is in broadcast levels), and where it's placed on backconversion to YUV

and don't forget about software codec color space ...