[July 1 2022] Cobalt 23.LTS.RC Release

The Cobalt team is thrilled to announce the RC (release candidate) of Cobalt 23 LTS!

cobalt / cobalt / refs/heads/23.lts.1+

  • Evergreen binaries are available on GitHub (3.1.3)

Cobalt 23 LTS includes Starboard API version 14 for porters and its release version will support all features that are required for 2023 YouTube Certification. The code is available at Cobalt open source "23.lts.1+” branch. (Read branching/versioning documents for more information) As this version is a release candidate, the code is subject to change while we expect to have no more Starboard API changes.

There are newly implemented features, improvements, and simplified code. We have outlined the changelist below with a brief description of Cobalt 23 LTS and Starboard 14 changes. More detailed information can be found in the respective CHANGELOG.md files (Cobalt, Starboard).

Cobalt Changes

See cobalt/CHANGELOG.md for more information.

New Features / Support

  • Added support for HTTP caching, improving app startup times
    • Compiled V8 JavaScript bytecode is also cached
  • Added Identifier for Advertising (IFA) support
  • Added experimental support for Web Workers
    • Dedicated Workers and Service Workers web specifications are partially implemented

Updates / Improvements

  • Improved device health monitoring with Watchdog features for detecting application hangs
  • Cobalt meta-build now uses GN ( Chrome Generate Ninja )
    • GYP is now deprecated
  • Evergreen supports LZ4 compressed binaries, saving up to 30% storage space
  • Reproducible builds are now supported for production configurations


  • GYP meta-build code is removed
  • Updated to Python3. Python2 support is removed
  • Starboard 11 support is removed. Starboard 12 and 13 are supported

New Requirements

  • C++17 toolchains are required

Starboard Changes

See starboard/CHANGELOG.md for more information.

New Features / Support

  • Added disk cache size constant
    • kSbMaxSystemPathCacheDirectorySize constant sets cache directory max size (minimum 24MB)
  • Added IFA advertising ID properties
    • kSbSystemPropertyAdvertisingId and kSbSystemPropertyLimitAdTracking returned from SbSystemGetProperty call

Updates / Improvements

  • Added a “Projector” device type
    • kSbSystemDeviceTypeVideoProjector as part of SbSystemDeviceType enumeration
  • 10-bit YUV decode target format added
    • kSbDecodeTargetFormat3Plane10BitYUVI420Compact as part of SbDecodeTargetFormat enumeration


  • Media player API old interfaces are cleaned up
  • Removed unused SystemPathTestOutputDirectory


  • GN migration guide
    • starboard/build/doc/migrating_gyp_to_gn.md
    • starboard/build/doc/migration_changes.md
    • starboard/build/doc/gn_migrate_stub_to_platform.md
  • Docker setup guide
    • cobalt/site/docs/development/setup-docker.md
  • Improved microphone detection capability with new PlatformService(soft_mac_platform_service.h)
    • Documentation available in SoftMicPlatformService (GitHub)
    • Demo available in (soft_mic_platform_service_demo.html)

2023 YouTube Certification

Use "23.lts.1+” branch while you develop your 2023 year devices. However, remember to use "23.lts.stable" for the 2022 YouTube certification and for your product release once the branch is available.

Contact Points

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