[FFmpeg-user] Prores 444 being detected by quicktime as 422?

[Roger Pack]

>> Incompatible pixel format 'yuv444p10le' for codec 'prores',
>> auto-selecting format 'yuv422p10le'
>
> Only the slower alternative prores encoder "prores_kostya"
> supports yuv444.

His question was, even using prores_kostya with yuv444p10le, the
resultant file shows as yuv44p10le in ffmpeg, but in QT Player, it
says "yuv420p" when playing it.
So my question is...do any files say yuv422 when played in QT Player?
-r