> On Nov 20, 2017, at 11:22 AM, Derek Buitenhuis <derek.buitenh...@gmail.com> 
> wrote:
> On 11/20/2017 3:19 PM, Dave Rice wrote:
>> TN2162 requires a colr atom for uncompressed yuv (including v210, v308, 
>> v408, etc) in mov, so I'd prefer to write it in this case. Note that the 
>> colr atom provides an option for unspecified for each of the color values, 
>> so there's a method to write a colr atom which basically says ¯\_(ツ)_/¯.
> [...]
>> I disagree. I'd prefer to follow the specification and write a colr atom (in 
>> the case of uncompressed yuv in mov) that say the colr is unspecified rather 
>> than to write no colr atom at all and create an invalid file. See 
>> https://developer.apple.com/library/content/technotes/tn2162/_index.html#//apple_ref/doc/uid/DTS40013070-CH1-TNTAG9.
>> I do agree that guesswork should be avoided or provided under an option that 
>> users could opt into. I suppose my preference order from support to oppose 
>> for writing uncompressed yuv in mov would be:
>> 1: write a colr atom in all cases (if unknown, use unspecified values in 
>> colr atom)
>> 2: write a colr atom if color data the known (no colr atom if unknown)
>> 3: write a colr atom in all cases (if unknown, just make stuff up, #yolo)
> My opinion falls somewhere in between, to something like this (in 
> pseudo-code):
>    if (colors_known) {
>        write_colr(vals);
>    } else if (uncompressed_yuv) {
>        if (guesswork_user_option) {
>            write_colr(guessed_hacky_crap);
>        } else {
>            write_colr(unspecified);
>        }
>    } else if (guesswork_user_option) {
>        write_colr(guessed_hacky_crap);
>    } else {
>        // Don't write a colr atom because it adds no value, to write 
> unspecified in it
>        // and no spec requires it for compressed streams.
>    }

What do you propose as the default for guessed_hacky_crap? Also are there 
supporters for the need of a guessed_hacky_crap optio? Is there precedence in 
ffmpeg to enable/disable guesswork via a user option?
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