> 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? Dave _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
