Mapping ColorSpace value into ColorModel

[gibix]

I'm looking for a solution for mapping values from matroska::elements::Video::colour_space into av_data::pixel::ColorModel as part of #9. The value are written in FourCC as described here.

Here is a first draft of the solution

const RAW: u32 = fourcc(b'r', b'a', b'w', b' ');

const fn fourcc(a: u8, b: u8, c: u8, d: u8) -> u32 {
    (d as u32) | (c as u32) << 8 | (b as u32) << 16 | (a as u32) << 24
}

// parse fourCC value into pixel::ColorModel
// TODO: assumed Big Endian
fn colour_space_to_color_model(colour_space: &[u8]) -> Option<ColorModel> {
    let mut fourcc_val: u32 = 0;

    for c in colour_space {
        let b = *c as u8;

        fourcc_val = (fourcc_val << 8) | b as u32
    }

    match fourcc_val {
        RAW => Some(ColorModel::Trichromatic(TrichromaticEncodingSystem::RGB)),
        _ => None
    }
}

1. There is no offocial list of the formats supported in the ColorSpace field Colour Space values ietf-wg-cellar/matroska-specification#337
2. I'm not sure how to match all values from fourcc's yuv into av_data::pixel::TrichromaticEncodingSystem

[lu-zero]

Ideally you can expose the fourcc as a struct FourCC(u32). and have the mapping as an esternal trait to move from and to the color model.