Constant CHUNK_LEN 

const CHUNK_LEN: u64 = _; // 4_194_304u64

Bytes per response. Large enough that a film needs relatively few round trips, small enough that one response is never a memory problem on a phone. Tauri’s asset protocol uses 1 MiB; 4 MiB quarters the request count for the multi-gigabyte files this exists to serve.