[FFmpeg-user] Levels and Primaries

Andy Furniss adf.lists at gmail.com
Mon Feb 3 22:37:27 CET 2014

Rio Kierkels wrote:
> Thank you guys for posting it, I've done just as requested but the
> dpx that is attached to the mail is stalling it because of it's size.
> It's awaiting moderation. I've also provided an mxf rendered by our
> studio with episode using the exact same dpx file. However that one
> is also awaiting moderation.
> In the mean time I'll just continue providing links as well to speed
> up the conversation. The dpx file can be found in the zip file that I
> refered to in my original post.
> Here you can find the episode rendered mxf file of the colorbars
> (Episode rendered mxf
> colorbars<https://drive.google.com/file/d/0B9hzJJkCcuUrMGZQX19oa1pPREU/edit?usp=sharing>

Well I don't know anything about dpx or mxf other than what I just read
on wikipedia :-)

I do however have some crap C I wrote once to count yuv and it shows the
levels on this as being wrong in that black is around 30 and white 218.

If I use your ffmpeg command to make the mxf from the bars in the zip
then the levels are roughly right (off by 1 and more spread than this).
Given my limited understanding of dpx I am not sure how 709 and 601
apply to it - I thought they were matricies to convert to/from RGB and
YUV, yet dpx seems more complicated than that (ie. it's not just RGB??).

> And here are the generated waveforms from it: lightworks (lightworks
> waveform episode rendered mxf
> colorbars<https://drive.google.com/file/d/0B9hzJJkCcuUrNzFWTGtZenRjLWM/edit?usp=sharing>
> ffmpeg (ffmpeg waveform episode rendered mxf
> colorbars<https://drive.google.com/file/d/0B9hzJJkCcuUrblVYUGlEajF3cGc/edit?usp=sharing>
> smoke (smoke waveform episode rendered mxf
> colorbars<https://drive.google.com/file/d/0B9hzJJkCcuUrbDBJbkpueDZDdE0/edit?usp=sharing>

So it looks like 0 and 100% with these tools are 16 and 235/240.

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