Function assemble_av1_tile_bitstream 

pub fn assemble_av1_tile_bitstream(tiles: Vec<(usize, Vec<u8>)>) -> Vec<u8> 

Assembles per-tile bitstreams into a single frame bitstream.

Format: [tile_count: u32 LE] ([tile_idx: u32 LE] [byte_len: u32 LE] [data …]) …