[Announcement] Cobalt 25.LTS.10 Release

[Dhaval Gandhi]

Cobalt 25 LTS Stable

The Cobalt team is thrilled to announce the stable release of Cobalt 25 LTS (25.lts.10.1034827) 

The Evergreen binaries are available on GitHub (5.10.2)

Cobalt 25 LTS includes Starboard API version 16 for porters and this stable release version supports all features that are required for 2025 YouTube Certification. The code is available at Cobalt open source 25.lts.10 branch. (Read branching and versioning documents for more information)

There are newly implemented features, improvements, and simplified code. We have outlined the changelist below with a brief description of Cobalt 25 LTS and Starboard 16 changes. 

Cobalt Changes 

(see cobalt/CHANGELOG.md for more information)

New Features / Support

• Chromium M114 Update: Upgraded most Chromium components to align with the M114 milestone release - including syncing the build environment and compilers.

• HTTP/3 with IETF QUIC: Integrated HTTP/3 with IETF standard QUIC for enhanced video playback performance in challenging network conditions.

• Immersive Audio Model and Formats (IAMF): Added support for IAMF audio.

• Android U Support: Extended compatibility to Android U

Updates/Improvements

• Embedded ICU Data: Linked ICU data directly into the Cobalt binary, reducing storage (via binary compression) and simplifying updates.

• Logging and Telemetry Enhancements: Improved logging and telemetry for update reliability and crash reporting. 

• Critical Stability fixes : Bug fixes and stability improvements. 

Evergreen

• LZ4 Compressed Binaries: Made LZ4 compressed binaries the default distribution format.

• Evergreen-Full on AOSP: Enabled Evergreen-Full support on AOSP (Android Open Source).

Starboard Changes 

(see starboard/CHANGELOG.md for more information)

New Features / Support

• POSIX API Adoption: Adopted POSIX APIs (see migration guide for details), reducing the total number of Starboard interface functions to 191 (vs 274 in Starboard 15).

• Partial Audio Frame Support: Introduced a new configuration constant (kHasPartialAudioFramesSupport) for partial audio frames.

Updates / Improvements

• pthread Migration: Migrated various components (e.g., SbConditionVariable, SbOnce, SbThreadLocalKey, etc…) to pthread. 

• Memory and File System Migration: Migrated memory allocation functions (SbMemoryAllocate, SbMemoryMap and others) to malloc, mmap and file system functions  (SbDirectoryOpen, SbDirectoryClose and others)  to equivalent opendir, closedir, etc.

• Socket API Migration: Migrated SbSocket to socket APIs.

• Starboard Extensions : Accessibility and onScreenKeyboard Starboard APIs are converted to Starboard Extensions (available in starboard/extension/accessibility.h and starboard/extension/on_screen_keyboard.h respectively).

• Build Standard Upgrade: Upgraded the C build standard to C11.

• Removed SB_C_NOINLINE.

• Deprecated SB_C_INLINE and removed config for SB_C_FORCE_INLINE.

• Removed configs for SB_EXPORT_PLATFORM and SB_IMPORT_PLATFORM.

• Configuration Changes:

• Changed MAP_EXECUTABLE_MEMORY from build-time to runtime config (kSbCanMapExecutableMemory).

• Additional Migrations: Migrated SbDirectoryCanOpen, SbFileExists, and SbFileGetPathInfo to start , and SbFileOpen, SbFileClose to open, close. 

Deprecations

• Deprecated Evergreen-x86 ABI: The x86 platform configurations, builds and ABI are no longer supported for Evergreen.

• OnScreenKeyboard: Deprecated OnScreenKeyboard.

• Unused Configurations: Deprecated various unused configurations (e.g., B_HAS_GLES2, SB_HAS_NV12_TEXTURE_SUPPORT, VIRTUAL_REALITY, DeployPathPatterns, SPEECH_SYNTHESIS, FILESYSTEM_ZERO_FILEINFO_TIME, SB_HAS_PIPE).

• Audio and Media:

• Deprecated SB_HAS_QUIRK(SUPPORT_INT16_AUDIO_SAMPLES).

• Deprecated SbMediaGetBufferAlignment, SbMediaGetBufferPadding and SbMediaGetBufferStorageType.

• Deprecated SbMediaIsBufferUsingMemoryPool, and memory pool is always used. (SbMediaIsBufferUsingMemoryPool is required to be true)

• Starboard Hash Configs: Deprecated Starboard hash configs.

2025 YouTube Certification

Remember to use "25.lts.10" for the 2025 YouTube certification and for your product release. Cobalt Known Issues with Status, Fixes, and Mitigations can be found in the YouTube Partner Portal.

Contact Points

Please contact our support channels if you have any problems, questions, or feedback.