Add 25.lts.1+ release announcement

cobalt/site/docs/releases/2025-lts-rc.md

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+Project: /youtube/cobalt/_project.yaml
+Book: /youtube/cobalt/_book.yaml
+
+# [Jul 1st 2024] Cobalt 25.LTS.1 Release Candidate
+
+## [Cobalt 25.lts.1 Release](https://developers.google.com/youtube/devices/living-room/cobalt/cobalt-evergreen-version-table)
+
+The Cobalt team is thrilled to announce the RC (Release Candidate) of [Cobalt 25
+LTS 1](https://github.com/youtube/cobalt/releases/tag/25.lts.1) !
+
+Evergreen binaries are available on GitHub
+([5.1.2](https://github.com/youtube/cobalt/releases/tag/25.lts.1))
+
+Cobalt 25 LTS includes Starboard API version 16 for porters and its Stable
+release version will support all features that are required for 2025 YouTube
+Certification. The code is available at Cobalt open source
+[25.lts.1+](https://github.com/youtube/cobalt/releases/tag/25.lts.1) branch.
+Read
+[branching](https://github.com/youtube/cobalt/blob/25.lts.1/cobalt/doc/branching.md)
+/
+[versioning](https://github.com/youtube/cobalt/blob/25.lts.1/cobalt/doc/versioning.md)
+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.
+
+IMPORTANT NOTE: As this version is a RC (Release Candidate), the code is
+subject to change while we expect to have no more Starboard API changes.
+**This is ready for integration and we STRONGLY RECOMMEND you start integration
+of this Cobalt 25 LTS RC on your respective platforms early and report issues
+ASAP** so there is ample time to investigate and resolve any detected issues
+before Cobalt 25 LTS Stable Release later this year.
+
+The Evergreen static version channels command (`co 25lts1`) can be used to
+update builds to the `25.LTS.1` Cobalt version for testing by following the
+steps provided
+[here](https://developers.google.com/youtube/devices/living-room/cobalt/cobalt-evergreen-faq).
+
+## Cobalt Changes
+
+[Full change log](https://github.com/youtube/cobalt/blob/25.lts.1/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
+    enhance video playback performance in challenging network conditions.
+
+*   **Immersive Audio Model and Formats (IAMF):** Added support for IAMF audio.
+
+*   **Android S Support:** Extended compatibility to Android S.
+
+### 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.
+
+### 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
+
+[Full change log](https://github.com/youtube/cobalt/blob/25.lts.1/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` etc…) to `malloc`, `mmap` and file system
+    functions (`SbDirectoryOpen` or `SbDirectoryClose` for example) 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 `stat` , 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.,
+    `SB_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_QU` (`SUPPORT_INT16_AUDIO_SAMPLES`).
+
+    *   Deprecated `SbMediaGetBufferAlignment`, `SbMediaGetBufferPadding`, and
+        `SbMediaGetBufferStorageType`.
+
+    *   Deprecated `SbMediaIsBufferUsingMemoryPool`, 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.stable` 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.
+
+Thank you,\
+On behalf of the Cobalt team