Number of tile columns to use, log2. Depending on the encoding width there are limitations on this value. The minimum values are 2 for width >= 1920 and 1 for width >= 1280. The minimum width of each tile is 256 pixels so the maximum values are 0 for width < 256, 1 for width < 512, 2 for width < 1024, 3 for width < 2048, 4 for width < 4096, 5 for width < 8192. If the value is too high or too low it will be overridden.