Re: [Cellar] Colour Format proposal

Sorry for the late answer, here are my comments:

On 22/01/2016 23:54, Frank Galligan wrote:
> [...]
>
> - I know some people expressed that they don't think starting from 
> FFmpeg for the TransferFunction is a good idea as they might have got 
> something wrong or too subjective. But I just used it as a starting 
> point for a list. I can reorder the list however we want. I also don't 
> think following another list, so we will be compatible with future 
> additions, will give us what we want as that list most likely will be 
> incomplete with something that is defined only in a different list. So 
> should we just start with a list, re-order it (so we are not 
> explicitly following it), then add what is currently missing? Then in 
> the future if someone needs to add something to the list it can be 
> brought up here?

That was me.
I am OK with that as long as we are clear that we don't follow FFmpeg list.

>
> [...]
>
> Element Name: Matrix
>
> Level:        5
>
> ID:           [55][A1]
>
> Mandatory:    -
>
> Multiple:     -
>
> Default:      2
>
> Type:         u
>
> Description:  Colour Matrix of the video. (0: IEC 61966-2-1 (sRGB), 1: 
> BT709,
>
>              2: Unspecified, 3: Reserved, 4: FCC, 5: BT470BG, 6: SMPTE 
> 170M,
>
>              7: SMPTE 240M, 8: YCOCG, 9: BT2020 Non-constant Luminance,
>
>              10: BT2020 Constant Luminance)
>


If we don't follow FFmpeg list, what is the purpose of  value 3 and why 
unspecified is 2 rather than 0?
Using FFmpeg list (which is based on MPEG list, with same oddities) is 
not bad, and I am not against it, just wondering if it is good to take 
the same oddities rather than a clean list without oddities.

Does anyone plan to transfer from DPX? If yes, we may need to add now 
missing elements in the list (e.g. "Printing density") but I am not 
expert enough for know which one is worth it.


>
>
> [...]
>
>
>
> Element Name: ChromaSubsampling
>
> Level:        5
>
> ID:           [55][A3]
>
> Mandatory:    -
>
> Multiple:     -
>
> Default:      0
>
> Type:         u
>
> Description:  (0: Unspecified, 1: 4:4:4, 2: 4:4:0, 3: 4:2:2, 4: 4:2:1, 
> 5: 4:2:0,
>
>              6: 4:1:1, 7: 4:1:0, 8: 3:1:1)
>

I am more, as some other people, for something more generic, e.g. 
ChromaSubsamplingHorz and ChromaSubsamplingVert, with a value of the 
subsampling (0 unspecified and default). I am afraid that someone crazy 
used e.g. a vertical subsampling of 4 (which can not be defined by X:X:X 
values), it is possible (and I have a file like that if I remember well) 
with FFV1.



>
> [...]
>
> Element Name: TransferFunction
>
> Level:        5
>
> ID:           [55][A7]
>
> Mandatory:    -
>
> Multiple:     -
>
> Default:      2
>
> Type:         u
>
> Description:  Transfer Function. (0: Reserved, 1: ITU-R BT.709, 2: 
> Unspecified,
>
>              4: Gamma 2.2 curve, 5: Gamma 2.8 curve, 6: SMPTE 170M,
>
>              7: SMPTE 240M, 8: Linear, 9: Log, 10: Log Sqrt,
>
>              11: IEC 61966-2-4, 12: ITU-R BT.1361 Extended Colour Gamut,
>
>              13: IEC 61966-2-1, 14: ITU-R BT.2020 10 bit,
>
>              15: ITU-R BT.2020 12 bit, 16: SMPTE ST 2084,
>
>              17: SMPTE ST 428-1 18: ARIB STD-B67 (HLG))
>
>
>
> Element Name: Primaries
>
> Level:        5
>
> Mandatory:    -
>
> Multiple:     -
>
> ID:           [55][A8]
>
> Default:      2
>
> Description:  (0: Reserved, 1: ITU-R BT.709, 2: Unspecified, 4: ITU-R 
> BT.470M,
>
>               5: ITU-R BT.470BG, 6: SMPTE 170M, 7: SMPTE 240M, 8: FILM,
>
>               9: ITU-R BT.2020, 10: SMPTE ST 428-1)
>

Same remark as with Matrix.

>
> [...]
>

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