[4.0.0] - 2026-1-23
API updates
- Major release with new API updates that are not backwards compatible.
- Extended the crf range to 70 reducing the impact or QP scaling allowing the encoder to reach lower bitrates
- Added quarter steps between qp and crf increments to allow for further granularity in qp selection
- Added support for setting a custom global logger for library consumers (!2570, !2579)
- Cleaned up public API headers including removal of deprecated macros, structs, and fields (!2565, !2568)
- Additionally cleaned up anything marked using SVT_AV1_CHECK_VERSION().
- Additionally cleaned up anything marked using SVT_AV1_CHECK_VERSION().
- Added ability to calculate per-frame PSNR and SSIM metrics (!2521)
- Allow sending more than 1 but less than 4 frames with avif mode (This is not for AVIF image sequence, but for encoding an alpha layer) (!2551, !2560)
- Added tune IQ and MS-SSIM for Still Image coding mode
Encoder
- Significant improvements in AVIF and still image modes (!2552,!2567):
- ~5-8x speedup M11-M0 at the same quality levels with tune MS-SSIM
- ~5-8% BD-Rate improvements at the same complexity with tune MS-SSIM
- Tradeoff improvements for the RTC modes (!2558):
- ~5-15% speedup at similar quality levels in --rtc mode across presets 7 - 11
- Completed porting all SVT-AV1-PSY applicable features for --tune vq for video and --tune iq for avif (!2484, !2489, !2491, !2494, !2496, !2503, !2504, !2507, !2514, !2522 , !2561, !2562, !2576)
- Update S-Frame support to allow setting it in a specific decode order option and with more qp options (!2477 !2523 !2534)
- Further Arm Neon and SVE2 optimizations that improve high bitdepth encoding by an average of ~5% in low resolutions
Cleanup, Build and bug fixes, testing and documentation
- General code cleanup, bugfixes, documentation and console output changes
- Bugfixes: Fixed an issue with the encoder hanging when given an input with a height of 24 pixels or less (!2518)
- Bugfixes:Fixed a bug that results in encoding an invalid bitstream when using rtc with a high QP value (!2502)
- Bugfixes:Fixed a hang with VBR encoding (#2300, !2535)
- Bugfixes:Fixed a hang when using recon output with low delay mode (#2315, !2544)
- Bugfixes:Fixed an encoder crash when using RTC with resolutions not divisible by 16 and presets >= 11 (#2301, !2547)
- Bugfixes:Fixed bitstream level tier compliance with AV1 specification (#2332, !2577, !2581, !2587)
- Cleanup: Removed in-tree gstreamer plugin (!2586)
- Cleanup: Code specific cleanup for slimmer binary sizes (!2476)
- Testing: Added CI coverage for compiling FFmpeg on macOS Arm (!2536)
- Testing: Added a python based testing framework for comparing codec performance and quality (!2532, !2550, !2556, !2563, !2564, !2566)