[FFmpeg-devel] Why is writing the colr atom not the default in the mov muxer?

tim nicholson nichot20 at yahoo.com
Tue Feb 24 09:00:07 CET 2015

On 21/02/15 01:34, Dave Rice wrote:
> Hi Robert, Kevin,
>> On Feb 20, 2015, at 9:56 AM, Robert Krüger <krueger at lesspain.de> wrote:
>> Am Freitag, 20. Februar 2015 schrieb Kevin Wheatley :
>>> On Fri, Feb 20, 2015 at 1:30 PM, Robert Krüger <krueger at lesspain.de
>>> <javascript:;>> wrote:
>>>> if I read the code correctly, the colr atom is only written in the mov
>>>> muxer if the flag write_colr is specified. Was that behaviour chosen to
>>>> have better backward compatibility or is there another reason not to
>>> write
>>>> this standard atom by default?
>>> I chose that way to preserve the older behaviour, as it can change how
>>> files will be interpreted.
>>> I assumed that but isn't the change then a change for the better (then
>> maybe requiring a version bump and an entry in the release notes)? After
>> all Apple muxers write it by default as well and not trusting the input
>> metadata seems to me like something that should be opt-out rather than
>> opt-in but that's just my 2c.
> That's also my two cents and I also wondered why users have to opt-in to a correctly written file. The QuickTime spec says that colr is required with some streams (such as raw uyvy422 and v210), see: https://developer.apple.com/library/mac/technotes/tn2162/_index.html#//apple_ref/doc/uid/DTS40013070-CH1-TNTAG9.
> I'd propose that colr be written by default. The interpretation may be different but, since a file with a colr atom is more self-descriptive, the interpretation is more likely to be correct.


> Dave Rice
>> [...]

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