ChunkReader.cs

using SixLabors.ImageSharp;
using SixLabors.ImageSharp.PixelFormats;

var bytes = File.ReadAllBytes("r.0.0.mca")[8192..];

var colors = new List<Rgba32>();

for (var index = 0; index < bytes.Length;)
{
    if (index + 15 > bytes.Length)
    {
        break;
    }

    var slice = bytes[index..(index += 15)];

    colors
        .AddRange(slice
            .Chunk(3)
            .Select(chunk => new Rgba32(chunk[0], chunk[1], chunk[2])));
}

var chunks = colors.Chunk(256);

var count = 0;

foreach (var chunk in chunks)
{
    using var image = new Image<Rgba32>(16, 16, Rgba32.ParseHex("#000000"));

    var horizontal = 0;
    var vertical = 0;

    foreach (var color in chunk)
    {
        if (horizontal == 16)
        {
            horizontal = 0;
            vertical++;
        }

        image[horizontal++, vertical] = color;
    }

    image.SaveAsPng($"Frames/{count++}.png");
}