SVT-AV1-4.2.0

[Bruce Dubbs]

New minor version.

[Xi Ruoyao]

Not yet finally released.

[Joe Locash]

Now at 4.2.0.

[Joe Locash]

## [4.2.0] - 2026-07-14

VOD / Random Access

- Added TUNE-VMAF mode targeting ~15% VMAF BD-rate improvement at minimal PSNR l
oss
- Implemented single-thread processing mode with RA handling
- RA preset tuning and bitrate optimization for M3-M5
- New CLI options: `--cqp`, `--enable-intrabc`, `--hbd-mds`, `--enable-kf-tf`
- Added raw OBU output format as an alternative to IVF
- Signal `initial_display_delay` in sequence header to fix A/V sync on seek

RTC / Low Delay

- Added CBR rate control with Kalman-filter QP estimation, cyclic refresh, and f
rame re-encode
- Added on-the-fly MG size, preset, bitrate, and frame rate changes
- Added reference frame management API with LTR support and two-layer RPS struct
ure
- Exposed `--max-intra-bitrate-pct` and `--max-inter-bitrate-pct` parameters
- Improved compression efficiency vs. cycle tradeoff across RTC presets
- Optimized memory footprint for RTC mode with small resolutions
- Further speed and quality tuning for RTC

Encoder (general)

- Refactored entropy coding: direct tile-buffer writes, arithmetic coder simplifications, coefficient shaving
- CDEF optimizations: 8-bit boundary-aware filter, persistent scratch buffers, luma/chroma specialization
- MD and ME optimizations (LPD1 early-skip, VLPD0 fast path, static-block ME bypass)
- Optimized still-image screen content detection
- Optimized TPL dispatch when TPL is disabled
- Added `ENABLE_STACK_PROTECTOR` CMake option to prevent the stack protector flag from being added

Arm

- Added lowbd (8-bit) int16 forward transform NEON kernels (4x4 through 32x32)
- Added Neon SAD, quantize-matrix, SSIM, VMAF, variance, and pixel projection error kernels
- Added SVE2 VMAF kernels and hardware CRC-32C for hash-based ME
- Optimized convolution, full distortion, and SAD calculation functions

Bug fixes and documentation

- Fixed superres recode crash, RESIZE_DYNAMIC under `--rtc`, RTC candidate-count overflow, recon output, and memory leak
- Fixed signed left-shift UB, OOB reads, and race conditions in rate control
- Added NVTX/Nsight Systems profiling hooks, PPC toolchain, and macOS universal binary support
- Addressed cppcheck warnings and rewrote affected unit tests
- Addressed USAN and MSAN warnings
- Reduced OBMC stack usage to fix a crash with PGO
- General code cleanup, documentation updates, and test improvements

Fixed at f31fec359f.