libsdl-org/aom
Oct 2025 – Apr 2026
6 Months active
Languages Used
CC++
Technical Skills
ARM NEON IntrinsicsARM Neon IntrinsicsAssembly OptimizationCode RefactoringImage ProcessingLow-level Optimization
Li Zhang
PROFILE
Li Zhang
Over six months, contributed to libsdl-org/aom by engineering performance and maintainability improvements for AV1 video processing on ARM architectures. Focused on optimizing Neon and I8MM convolution and variance paths in C and C++, the work accelerated both encoding and decoding, reduced instruction latency, and improved SIMD utilization. Addressed build system reliability by decoupling high-bit-depth and standard paths, enhancing CI stability. Enhanced AV1 temporal filtering with SIMD optimizations and robust unit tests, supporting larger block sizes and cross-architecture compatibility. The approach emphasized low-level optimization, code refactoring, and rigorous testing, resulting in faster, more reliable video processing across diverse ARM-based devices.
Overall Statistics
Feature vs Bugs
82%Features
Repository Contributions
19Total
Bugs
2
Commits
19
Features
9
Lines of code
3,798
Activity Months6
Your Network
590 peopleSame Organization
@arm.com538
Work History
April 2026
1 Commits • 1 Features
Apr 1, 2026Monthly summary for 2026-04 (libsdl-org/aom): In April 2026, delivered ARM NEON-accelerated AV1 high bit-depth temporal filtering enhancements, enabling 64x64 temporal filter blocks and introducing a specialized 4:2:0 luma SSE sum path. Added assertions to enforce block-size constraints for performance and correctness. Fixed bug 493082083. Result: improved performance on ARM devices and more robust AV1 high-bit-depth filtering.
1 Commits • 1 Features
Apr 1, 2026Monthly summary for 2026-04 (libsdl-org/aom): In April 2026, delivered ARM NEON-accelerated AV1 high bit-depth temporal filtering enhancements, enabling 64x64 temporal filter blocks and introducing a specialized 4:2:0 luma SSE sum path. Added assertions to enforce block-size constraints for performance and correctness. Fixed bug 493082083. Result: improved performance on ARM devices and more robust AV1 high-bit-depth filtering.
April 2026
March 2026
3 Commits • 2 Features
Mar 1, 2026March 2026 monthly summary for libsdl-org/aom focusing on AV1 temporal filter improvements and test reliability. Key features delivered: - AV1 Temporal Filter Performance Optimizations and 64x64 Block Size Support: Implemented SIMD SSE path for luma sum calculations in av1_apply_temporal_filter for color format 420 and updated Neon/Neon Dotprod support to enable 64x64 TF_BLOCK_SIZE, improving processing efficiency and scalability across architectures. Major bugs fixed: - Resolved Neon/Neon Dotprod integration enabling 64x64 path in av1_apply_temporal_filter (aomedia:493082083), addressing cross-arch portability issues and correctness for larger block sizes. Enhanced unit tests and reliability: - Enhanced apply_temporal_filter unit tests with tighter pixel-value constraints, corrected input buffer plane_offset, and expanded validation across all color planes to reduce regressions and improve test reliability. Overall impact and accomplishments: - Substantial performance uplift and scalability for AV1 temporal filtering across devices, enabling faster processing on ARM and x86 platforms while maintaining visual quality. - Stronger test coverage reduces risk of regressions in future changes and improves maintainability of the temporal filter codepath. Technologies/skills demonstrated: - SIMD optimizations across architectures (SSE for x86, Neon/Neon Dotprod for ARM) - 64x64 block size support in AV1 temporal filtering - Rigorous unit test design, buffer management, and cross-plane validation - Change-driven development with attention to bug tracking and release readiness
March 2026
3 Commits • 2 Features
Mar 1, 2026March 2026 monthly summary for libsdl-org/aom focusing on AV1 temporal filter improvements and test reliability. Key features delivered: - AV1 Temporal Filter Performance Optimizations and 64x64 Block Size Support: Implemented SIMD SSE path for luma sum calculations in av1_apply_temporal_filter for color format 420 and updated Neon/Neon Dotprod support to enable 64x64 TF_BLOCK_SIZE, improving processing efficiency and scalability across architectures. Major bugs fixed: - Resolved Neon/Neon Dotprod integration enabling 64x64 path in av1_apply_temporal_filter (aomedia:493082083), addressing cross-arch portability issues and correctness for larger block sizes. Enhanced unit tests and reliability: - Enhanced apply_temporal_filter unit tests with tighter pixel-value constraints, corrected input buffer plane_offset, and expanded validation across all color planes to reduce regressions and improve test reliability. Overall impact and accomplishments: - Substantial performance uplift and scalability for AV1 temporal filtering across devices, enabling faster processing on ARM and x86 platforms while maintaining visual quality. - Stronger test coverage reduces risk of regressions in future changes and improves maintainability of the temporal filter codepath. Technologies/skills demonstrated: - SIMD optimizations across architectures (SSE for x86, Neon/Neon Dotprod for ARM) - 64x64 block size support in AV1 temporal filtering - Rigorous unit test design, buffer management, and cross-plane validation - Change-driven development with attention to bug tracking and release readiness
February 2026
4 Commits • 1 Features
Feb 1, 2026February 2026: Delivered performance-oriented AV1 encoder Neon variance path optimization for ARM in libsdl-org/aom, consolidating variance paths and removing the Armv8.4 DotProd 4x4 kernel in favor of the faster Armv8.0 Neon 4x4 path. Refactored subpel variance calls to directly use optimized Neon variance paths and introduced Armv8.4 Neon DotProd subpel variance paths for larger block sizes, including unit tests. Fixed GCC 15 brace warnings in ARM code (pickrst_sve.h) to ensure forward-compatible builds. These changes draw on SVT-AV1 porting work and improve encoder throughput for small blocks while improving maintainability and cross-ARM compatibility.
4 Commits • 1 Features
Feb 1, 2026February 2026: Delivered performance-oriented AV1 encoder Neon variance path optimization for ARM in libsdl-org/aom, consolidating variance paths and removing the Armv8.4 DotProd 4x4 kernel in favor of the faster Armv8.0 Neon 4x4 path. Refactored subpel variance calls to directly use optimized Neon variance paths and introduced Armv8.4 Neon DotProd subpel variance paths for larger block sizes, including unit tests. Fixed GCC 15 brace warnings in ARM code (pickrst_sve.h) to ensure forward-compatible builds. These changes draw on SVT-AV1 porting work and improve encoder throughput for small blocks while improving maintainability and cross-ARM compatibility.
February 2026
December 2025
1 Commits
Dec 1, 2025Monthly summary for 2025-12 focusing on libsdl-org/aom. Delivered a critical build stability improvement by decoupling standard bit-depth and high-bit-depth paths, preventing compilation failures in standard builds. The changes also cleaned up headers and moved high-bit-depth code out of standard build paths, improving maintainability and cross-build reliability. This work reduces CI failures and accelerates integrations for downstream clients relying on standard builds, while preserving the high-bit-depth functionality.
December 2025
1 Commits
Dec 1, 2025Monthly summary for 2025-12 focusing on libsdl-org/aom. Delivered a critical build stability improvement by decoupling standard bit-depth and high-bit-depth paths, preventing compilation failures in standard builds. The changes also cleaned up headers and moved high-bit-depth code out of standard build paths, improving maintainability and cross-build reliability. This work reduces CI failures and accelerates integrations for downstream clients relying on standard builds, while preserving the high-bit-depth functionality.
November 2025
5 Commits • 3 Features
Nov 1, 2025Month 2025-11: Delivered targeted ARM-optimized AV1 convolution enhancements in libsdl-org/aom, plus a maintainability-focused constants refactor. The work accelerates AV1 weighted convolution on ARM platforms and improves code quality with broader tests and centralized constants.
5 Commits • 3 Features
Nov 1, 2025Month 2025-11: Delivered targeted ARM-optimized AV1 convolution enhancements in libsdl-org/aom, plus a maintainability-focused constants refactor. The work accelerates AV1 weighted convolution on ARM platforms and improves code quality with broader tests and centralized constants.
November 2025
October 2025
5 Commits • 2 Features
Oct 1, 2025October 2025 monthly summary for libsdl-org/aom: Focused on ARM AV1 performance optimization and maintainability. No major bugs fixed this month; all work targeted performance improvements and code quality. Resulting in faster and more power-efficient AV1 decoding on ARM devices, enabling broader device support and smoother playback. Demonstrated proficiency in ARM Neon intrinsics, I8MM optimization, and code refactoring for naming consistency.
October 2025
5 Commits • 2 Features
Oct 1, 2025October 2025 monthly summary for libsdl-org/aom: Focused on ARM AV1 performance optimization and maintainability. No major bugs fixed this month; all work targeted performance improvements and code quality. Resulting in faster and more power-efficient AV1 decoding on ARM devices, enabling broader device support and smoother playback. Demonstrated proficiency in ARM Neon intrinsics, I8MM optimization, and code refactoring for naming consistency.
Activity
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Quality Metrics
Correctness98.4%
Maintainability85.2%
Architecture92.6%
Performance98.0%
AI Usage20.0%
Skills & Technologies
Programming Languages
CC++
Technical Skills
ARM NEON IntrinsicsARM Neon IntrinsicsARM architectureAssembly OptimizationC programmingC++ developmentC++ programmingCode RefactoringImage ProcessingLow-level OptimizationNeon programmingPerformance OptimizationPerformance TuningSIMD optimizationVideo Codec Optimization
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