Crate rusty_h264_decoder 

Pure-Rust H.264 decoder — Constrained Baseline + B-slices + most of High profile, CAVLC and CABAC.

Validated bit-exact against Cisco’s h264dec on 35 of 35 clean streams from openh264’s conformance corpus; the CABAC paths were brought up symbol-by-symbol against an instrumented openh264 oracle and are gated pixel-exact vs ffmpeg. The reconstruction path is shared with the encoder (via rusty_h264-common), so the two halves agree bit-for-bit by construction.

Decodes: full intra (I_16x16/I_4x4/I_8x8/I_PCM), inter (P_Skip/16×16/16×8/8×16/P_8x8) with quarter-pel motion compensation, B-slices (temporal + spatial direct, implicit + explicit weighted prediction), the 8×8 transform and 8×8 intra prediction, scaling matrices, in-loop deblocking, and a multi-reference DPB with POC reordering and MMCO. CABAC covers I, P and B slices (not yet: I_PCM, High-profile 8×8 residual).

This crate is #![forbid(unsafe_code)] and is fuzzed to never panic or hang on malformed input — errors surface as DecodeError.

Decoder::decode_stream is the one-call entry point (frames in display order); Decoder::decode is the streaming form (one picture per access unit, in decode order — pair it with Decoder::last_poc).

Modules

cabac_test

Structs

Decoder

A Constrained Baseline H.264 decoder. Holds the most recent parameter sets and the previous decoded picture (the inter reference) across calls.

MvField

One frame’s motion field, in 4x4-block raster (mb_w*4 wide).

Pps

Parsed picture parameter set fields the decoder needs.

Sps

Parsed sequence parameter set fields the decoder needs.

Enums

DecodeError

Decode errors.

Statics

MV_DUMP

Frames captured in decode order when RFF_MV_DUMP=1. Diagnostic only.

Functions

split_access_units

Splits an Annex-B byte stream into access units, each ending after a VCL (coded-slice) NAL with any preceding parameter-set/SEI NALs attached. Start codes are preserved so each unit can be passed straight to Decoder::decode.