nx_av1_obu_gate.nx

nx_av1_obu_gate.nx -- proves the AV1/AV2 OBU layer by ROUND-TRIP. T2 pins LEB128 to its canonical encodings absolutely (128 -> 0x80 0x01), because a writer that emits a longer-than-necessary form still round-trips against its own reader while producing streams other decoders reject. T6/T7 are the security-shaped ones: obu_forbidden_bit and obu_reserved_1bit must both be REFUSED. A parser that ignores them consumes arbitrary bytes as headers and resynchronises onto garbage -- the standard way a malformed file becomes a long walk through memory. T8 also bounds LEB128 at 8 bytes, so a continuation run cannot march off the buffer. T4 separates UVLC from LEB128. They are both 'variable length' and they are not the same code; confusing them misreads every frame-header field after the first, silently. license_tier: ORIGINAL