[FFmpeg-user] FFMPEG introduces color shift to DNxHD MOVs

[James Zhang]

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On Fri, Jul 6, 2012 at 8:52 PM, Nathan Rusch <nathanrusch at gmail.com> wrote:

> I wanted to follow up on this for posterity (in case anyone else comes
> down this same road).
>
> I was able to get the colors to match 1:1 to the source by adding a
> colormatrix operation to the conversion process via libavfilter. The flag
> and value added are:
>
> -vf colormatrix=bt601:bt709
>
> Thanks again for getting me moving in the right direction Mike.
>
>
> -Nathan
>
>
> -----Original Message----- From: Mike Scheutzow
> Sent: Friday, July 06, 2012 10:21 AM
> To: FFmpeg user questions and RTFMs
> Subject: Re: [FFmpeg-user] FFMPEG introduces color shift to DNxHD MOVs
>
> Nathan Rusch wrote:
>
>> Hello all,
>>
>> In trying to troubleshoot another issue, I’ve run across a subtle,
>> consistent color shift being introduced by FFMPEG to DNxHD-encoded
>> MOVs. Thus, they fail to match both DNxHD MOVs generated with the
>> Avid codec, as well as both MOVs’ common source material (an 8-bit
>> RGB TIFF sequence).
>>
>
>
> ffmpeg always assumes the BT.601 colorspace when converting from
> RGB->YUV and from YUV->RGB. A patch to fix this is welcome, but no one
> has ever cared enough to provide it.
>
> So if you do:
>
> ffmpeg:     RGB -> [BT.601 matrix] -> YUV
>
> other tool: YUV -> [BT.709 matrix] -> RGB
>
> then you get a color shift like you describe.
>
> Workaround: feed ffmpeg with a file containing YUV that's been properly
> converted.
>
>
> Mike Scheutzow
>
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