Function macroblock_filter_horizontal

pub(crate) fn macroblock_filter_horizontal(
    hev_threshold: u8,
    interior_limit: u8,
    edge_limit: u8,
    pixels: &mut [u8],
)

Part of the normal filter described in 15.3 in the specification

Filters on the 8 pixels on the horizontal edges between macroblocks
The pixels passed in must be a slice containing the 4 pixels on each macroblock