[FFmpeg-user] convert from bt601 to bt709

[Rio Kierkels]

On 10 June 2014 16:39, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

> Gregory Ducatel <gducatel <at> gmail.com> writes:
>
> > ffmpeg.exe -y -threads 8 -f image2
>
> The dpx decoder is currently not multi-threading
> capable: This would be trivial to add but I wonder if
> it helps performance in any case (I/O should be slower
> than dpx decoding).
>
> > -r 24000/1001
>
> (Unrelated: This may be unnecessary because FFmpeg
> does read the framerate field from dpx images now.
> It is of course necessary with the workaround below.)
>
> > -i "Source_file.%04d.dpx"
> > -sws_flags full_chroma_inp+full_chroma_int+accurate_rnd+print_info
> > -c:v dnxhd -pix_fmt yuv422p -b:v 115M
> > -vf "[in]scale=1920:1080,colormatrix=bt601:bt709[out]"
> > -movflags +faststart -aspect 1.777778 "c:\test_dnxhd.mov"
>
> I was unable to find a possibility to make FFmpeg assume
> MPEG range for the input sample (and I was unable to find
> any hint within the dpx file that it is not full scale
> which is expected for rgb afaict, if somebody could help
> with the detection, it would be useful!), you currently
> have to cheat:
>
> $ ffmpeg -i input.dpx -f rawvideo
> -sws_flags full_chroma_inp+full_chroma_int+accurate_rnd+print_info
> -pix_fmt yuvj422p out
>
> (You could probably compress the output, in any case you
> can use -f image2 -vcodec rawvideo if that suits your
> needs better.)
>
> $ ffmpeg -f rawvideo -s 1920x1080 -r 24000/1001 -pix_fmt yuv422p
> -i out -vcodec dnxhd -vb 115M -movflags +faststart out.mov
>
> Note the different colour spaces used for writing and reading.
> Above may not be perfect but since you are converting
> from 10bit to 8bit with subsampling I would (perhaps
> wrongly?) assume that the output does not have to
> be perfect.
> In any case: Please test and let me know if this is
> closer to what you expect.
>
> I would open a ticket but I am still hoping for a
> checkerboard or at least a dpx sample with large
> white and black areas.
>
> Carl Eugen
>
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>

I've got a nice sequence in Full range RGB BT.709 dpx. 1920x1080 with a
checkerboard, ARIB-STD B28 colorbars, a resolution chart and of course
Kodak's Marcie.
I'll zip it up and put it somewhere to download in the next half hour.

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