rff-codec-av2

AV2 decoding for remade_ffmpeg_rs, backed by the pure-Rust rusty_av2d engine — no C, no FFI.

This crate is a thin adapter. register() wires the decoder into a CodecRegistry; a private wrapper translates between the rff Decoder trait and rusty_av2d's push/pull API. All codec logic — the decoder that is byte-identical to AOM's avmdec across a 45-clip conformance corpus — lives in rusty_av2d.

Decode robustness in debug builds

Two separate rusty_av2d (≤ 0.2.11) behaviours used to bite debug builds only; release builds were never affected. Both are fixed — this crate requires rusty_av2d ≥ 0.2.12:

• Empty packet → process abort. rusty_av2d's input validation calls abort() under debug_assertions when handed zero bytes (STATUS_STACK_BUFFER_OVERRUN on Windows). An abort is not a panic, so catch_unwind cannot contain it. This adapter now rejects empty or oversized packets with Error::InvalidData before they reach the engine, in every build — the same guard the AVIF adapter has for rav1d.
• av2_gdf.rs:549 overflow → ordinary panic. The GDF stripe base is computed as (i_min - 1) in usize, which underflows on the first stripe of every GDF frame (valid input included) and panics under overflow checks. Release wraps to exactly the intended address — av2f_still decodes byte-identically to the reference there. Fixed upstream in rusty_av2d 0.2.12 (add before subtracting — the same address in every build), so debug builds decode GDF content with overflow checks on and need no override.

let mut registry = rff_codec::CodecRegistry::new();
rff_codec_av2::register(&mut registry);
let mut decoder = registry.find_decoder(rff_core::CodecId::Av2)?;

From the CLI, AV2 in an IVF container (fourcc AV02) is detected automatically:

rff -i input.ivf -c:v rawvideo out.y4m

Scope

Decode only — there is no AV2 encoder, and the registry does not advertise one.

Research preview. AV2 is not a finalized standard: there are no official conformance vectors, correctness is defined against the AVM reference as of the pinned rusty_av2d release, and the bitstream may still change. Performance is unoptimized. See rusty_av2d's STATUS.md for the full scope statement.

Monochrome (4:0:0) output is refused rather than approximated — no corpus clip exercises it.

Linking alongside AV1

rusty_av2d and rusty_av1d share the dav1d symbol lineage, so their C ABI and assembly table exports collide at link time. This crate depends on rusty_av2d with default-features = false, which drops both and leaves the safe Rust API — that is how this workspace links AV1 and AV2 into one binary.

License

Apache-2.0 (this adapter). The underlying rusty_av2d engine is BSD-2-Clause.