[FFmpeg-user] dpx to prores & h.264 - color shift

Andy Furniss adf.lists at gmail.com
Mon Oct 17 21:37:43 EEST 2016

Andy Furniss wrote:
> Andreas Hummel wrote:
>> Hello Kevin, thanks for the hint. I replaced the -colormatrix option
>> with the -vf scale=.. option you suggested but i'm still getting a
>> slight hue shift in the final converted movie.
>> Even the added -sws_flags you suggested thx @Andy couldn't solve the
>>  problem. I tried various combinations but somehow i can't get a
>> color correct output with ffmpeg so far.
>> ffmpeg.exe -loglevel verbose -y -f image2 -start_number 0 -r 25 -i
>> INPUT -r 25 -vcodec prores_ks -profile:v 3 -pix_fmt yuv422p10le -vf
>> scale=in_range=full:in_color_matrix=bt709:out_range=tv:out_color_matrix=bt709
> -sws_flags accurate_rnd+full_chroma_int+full_chroma_inp+bitexact
>> -color_primaries bt709 -color_trc bt709 -colorspace bt709 -vendor
>> ap10 OUTPUT.mov
>> [Parsed_scale_0 @ 00000000025899a0] w:iw h:ih flags:'bicubic'
>> interl:0 [graph 0 input from stream 0:0 @ 0000000002587ba0] w:1920
>> h:1080 pixfmt:gbrp10le tb:1/25 fr:25/1 sar:1/1 sws_param:flags=2
>> [graph 0 input from stream 0:0 @ 0000000002587ba0] TB:0.040000
>> FRAME_RATE:25.000000 SAMPLE_RATE:nan [Parsed_scale_0 @
>> 00000000025899a0] w:1920 h:1080 fmt:gbrp10le sar:1/1 -> w:1920
>> h:1080 fmt:yuv422p10le sar:1/1 flags:0x4
> I can see from that that the -sws_flags didn't take.

More testing - Seems I am wrong here. Appending like I said will
show different, but with loglevel debug you can see the flags do
get set with -sws_flags and md5sum shows the same results.

> I don't have your input and like Carl Eugen said the upload site is so
> annoying I haven't seen your output either. Even if I had I don't know
> how it was made or how good any 10 -> 8 bit conversion was, plus I would
> be viewing on a crappy tn panel which likely doesn't even do 8 bit.
> I did a test with some 48 bit rgb sgi images
> In summary rather than -sws_flags appending below to the scale command
> :flags=accurate_rnd+full_chroma_int+full_chroma_inp+bitexact
> got a different output for me. I don't know how you would test 10 bit
> though as making/displaying jpg involves another conversion, which may
> give different output depending on what/what parameters are involved.

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