[Matroska-devel] [Cellar] Colour Format proposal

Hendrik Leppkes h.leppkes at gmail.com
Thu Jan 14 13:11:42 CET 2016


On Thu, Jan 14, 2016 at 1:04 PM, Steve Lhomme <slhomme at matroska.org> wrote:
> 2016-01-06 23:30 GMT+01:00 Frank Galligan <frankgalligan at gmail.com>:
>>
>>
>> On Tue, Jan 5, 2016 at 1:58 PM, Jerome Martinez <jerome at mediaarea.net>
>> wrote:
>>>
>>> Thanks for your detailed proposal.
>>> It is a lot of items, I am not expert in all domains but I have some
>>> comments:
>>
>> Neither am I, but I figured we might as well start from a proposal and
>> iterate from there.
>>
>>>
>>> Name: MatrixCoefficients (or Matrix. You don't use "Colour" with
>>> "Primaries" element, so I would not use it here too)
>>
>>  Sounds good to me.
>>
>>>
>>>
>>>
>>>
>>>
>>> Element Name: BitsPerChannel
>>> Level:        5
>>> ID:           [55][A2]
>>> Mandatory:    ma
>>> Multiple:     -
>>> Default:      8
>>> Type:         u
>>> Description:  Number of bits per channel. This number may be less for
>>> specific
>>>               channels depending on the ColourFormat and
>>> ChromaSubsampling.
>>>
>>>
>>>
>>> BitsPerChannel is misleading, used to be the technical count of bits.
>>> I propose QuantizationBits or ValidBitsPerChannel
>>> Not mandatory, not default (this value is often unknown)
>>
>> When authoring the video, I'm not sure why the software would not know the
>> bits per channel. Can you describe a use case where the this is unknown?
>
> When remuxing an older file. Either from Matroska source or AVI or other.
>
> Now if elements are mandatory with a default value to "unknown" it's fine.
>

Whats the point of a mandatory element with an "unknown" default? Just
make it optional then?

- Hendrik


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