SVT-AV1-4.1.0

[Bruce Dubbs]

New minor version.

[Joe Locash]

## [4.1] - 2026-03-16

Encoder

- Refactor MD, EncDec, and Entropy Coding kernels (!2604)
- Improve Still Image coding efficiency (!2612, !2614)
- Change Wiener Filter level for chroma for presets M3 and below (!2620)
- Optimize Screen Content coding for Still Image (!2630)

Arm

- Refactor Subpixel Variance kernels (!2608)
- Optimize 16b SAD kernel (!2610)
- Fixed Neoverse V2 unit test detection (!2622)
- Update Arm build guide (!2625)

Bug fixes and documentation

- Fixed a hang caused by improper variable looping (#2338, !2600)
- Add missing option 2 for `--enable-dlf`'s help output (!2601)
- Depth Refinement algorithmic bug fix (!2602)
- Add mutexes to fix hangs when running multiple instances of the encoder in one process (!2603, !2605, !2619)
- Fix motion calculation for cyclic QP refresh (!2613)
- Fixed a Debug vs Release mismatch (!2618)
- Fixed some new warnings with newer GCC versions (!2621)
- Changed Temporal Filtering distortion calculation to not include padding (!2623)
- Cleanup some dead unit tests (!2626)
- Benchmark framework improvements (!2627)
- CI/CD improvements (!2628)
- Fixed some niche crashes (!2629)
- General code and doc cleanup (!2606, !2607, !2609, !2611, !2616, !2617, !2624, !2631)

Fixed at 06690c0594.