CRT v0.4.0-preview.1

CRT v0.4.0-preview.1

First public developer preview of the CRT Graphics/Media SDK stage
(04-gfx-media). Pre-1.0: interfaces may change, and this is not a
production-ready release.

CRT is a Bionic-compatible cross-platform C runtime and Platform Adaptation
Layer (PAL). You rebuild Linux/BSD/Android-style native C/C++ source with your
own Clang/LLD toolchain against a CRT sysroot, and get native Linux, Windows,
and macOS executables. No VM, no container, and no compiler bundled in the SDK.

Demo (Windows, the media-player example decoding a clip with FFmpeg into a
native window):

Windows-demo-MediaPlayer.mp4

In this preview, media-player decodes in software on every platform.
The packaged crtmedia_player_demo does not request hardware decode, so it
always uses the software path -- on Windows, macOS, and Linux alike --
regardless of what that host's FFmpeg build supports. Hardware H.264 decode
itself is real and verified on all three platforms (see the table below);
its evidence is each platform's own crtmedia_hw_decode_test, not this demo.
The demo will request hardware decode by default starting with the next
preview.

What is in this preview

04-gfx-media is the current public SDK milestone. The SDK stages are
cumulative, so the 04-gfx-media archive already contains everything below it.

Stage	Adds
01-c	libc, libm, libdl, startup objects, shell, mksh, toybox, awk, make
02-cxx	imported libc++, libc++abi, and libunwind
03-gfx-simple	native window, keyboard and mouse input, software framebuffer
04-gfx-media	Skia CPU and GPU rendering, GPU presentation, FreeType text, FFmpeg software media, native audio output, opt-in hardware H.264 decode

Bundled third-party payload in 04-gfx-media: Skia m148, FreeType 2.14.3, and
a narrow LGPL FFmpeg 8.1.2 build (MOV/MP4/M4A, WAV, MP3 demux; H.264, AAC, MP3,
and PCM software decode). Each SDK's manifest.json lists these, plus the
external prerequisites CRT does not bundle.

Packaged examples: gfx-simple, gfx-gpu, gfx-skia, and media-player,
each with its own CMakeLists.txt that rebuilds it against the SDK, plus
ready-made programs under examples\bin.

Real upstream software rebuilt through the CRT sysroot with its own
configure/make (or GN) flow: zlib, libpng, SQLite, bzip2, xz, PCRE2,
mbedTLS, libcurl (real HTTP and HTTPS round trips), libffi, expat, FreeType,
FFmpeg, and Skia. Recipes and per-host results are in
docs/porting_status.md.

What has been verified

State on each host, not a promise. "Partial" means a gap stated below.

Capability	Linux	Windows	macOS
libc / libm / libdl, libc++ runtime, pthread, sockets, mmap, TLS	Verified (libdl: partial)	Verified	Verified
Native window and input	Verified (Wayland)	Verified (Win32)	Verified (Cocoa)
Skia CPU raster and text	Verified	Verified	Verified
Skia GPU (Ganesh) presentation	Verified (Vulkan, physical GPU)	Verified (D3D12)	Verified (Metal)
FFmpeg software media	Verified	Verified	Verified
Native audio output	Partial	Verified (WASAPI)	Verified (CoreAudio)
Hardware H.264 decode, frames delivered to the CPU	Verified (VA-API, physical GPU)	Verified (D3D11VA)	Verified (VideoToolbox)

The last full ctest runs were 149/149 on Windows/x64, 121/121 on
Linux/x86_64 under WSL2 (two TTY-dependent termios tests excluded from that
non-interactive run), 132/132 on a native Linux/x86_64 desktop with
CRTMEDIA_ENABLE_FFMPEG=ON and VA-API enabled, and 132/132 on macOS/arm64. The
Linux/aarch64 results come from its recorded acceptance runs. Per-host details
and dates are in
STATUS.md.

For this release specifically (Windows/x64): the SDKs were built with
CRT_RELEASE_TAG=v0.4.0-preview.1 from commit fd01d7c. The 04-gfx-media SDK
was built from the extracted 03-gfx-simple archive with empty caches in about
50 minutes, and passed its 8 stage tests, rebuilding and running the installed
gfx-gpu, gfx-skia (D3D12, with resize and pixel checks), and media-player
examples, and verify_dist.py. The published archive was then extracted into a
path containing a space, its prebuilt demos ran, and the quick start below was
run from it.

For the macOS/arm64 assets, which were added after the release was first
published: they are built from commit 972d913, not from the tag commit
fd01d7c (see the note under Downloads for why). The SDKs were built with
CRT_RELEASE_TAG=v0.4.0-preview.1 from a fresh clone on macOS 26.6.2 with
Apple clang 21.0.0. The 04-gfx-media SDK was built from the extracted
03-gfx-simple archive with empty caches in about 7.5 minutes, and passed its 8
stage tests, rebuilding and running the installed gfx-gpu, gfx-skia (Metal,
with resize and pixel checks), and media-player examples, and
verify_dist.py. The archive was then extracted into a path containing a space,
its prebuilt media-player and Metal demos ran, and the macOS quick start below
was run from it.

For the Linux/x86_64 assets, added the same day as the Linux VA-API hardware-
decode tranche closed: they are built from commit a90bf10, not from the
tag commit fd01d7c (see the note under Downloads for why). The SDKs were
built with CRT_RELEASE_TAG=v0.4.0-preview.1 from a fresh clone on a native
(non-VM, non-WSL) Ubuntu desktop with a physical Intel GPU, Clang 21.1.8, and
CMake 4.2.3. The 04-gfx-media SDK was built from the extracted
03-gfx-simple archive with empty caches in about 14 minutes (FreeType and
FFmpeg about 11 minutes, Skia about 3), and passed its 8 stage tests,
rebuilding and running the installed gfx-gpu, gfx-skia (Vulkan, with resize
and pixel checks), and media-player examples, and verify_dist.py. Both
03-gfx-simple and 04-gfx-media archives were then extracted into a path
containing a space: 03-gfx-simple's ready-made and freshly rebuilt
crtgfx_window_demo/crtgfx_window_example both presented 60 frames,
04-gfx-media's prebuilt crtmedia_player_demo presented 25 frames (software
decode -- this demo does not request hardware decode, so it decodes in
software on every host; the real hardware-decode evidence is
crtmedia_hw_decode_test, not this demo), and its prebuilt
crtgfx_skia_gpu_window_demo presented 5 real-Vulkan frames with a pixel
check passing, and the Linux quick start below was run from it.

Downloads

This release attaches Windows/x64, macOS/arm64, and Linux/x86_64 assets.

Windows/x64

Asset	Size	SHA-256
crt-v0.4.0-preview.1-windows-x86_64-04-gfx-media.zip	160.8 MB	66db007480300efbf69c45bacb53e2c019afafafbb802a0ccda26952a4893e6c
crt-v0.4.0-preview.1-windows-x86_64-03-gfx-simple.zip	122.9 MB	aa3b8b150e3bb2f3069564fb85a747c13e93fbbd0cca503263cb2e740c4fd874
crt-v0.4.0-preview.1-windows-x86_64-02-cxx.zip	122.6 MB	bdf345814a9141bb608496fe181bc55047e3af3818c9e724125317253757be65
crt-v0.4.0-preview.1-windows-x86_64-01-c.zip	113.7 MB	abd63b55e91fca2eaf0506ac9a75d7d691f6ad7e353bbd47cee51d35cacde64a
crt-v0.4.0-preview.1-windows-04-gfx-media-source.tar.xz	18.2 MB	15e34bae5d8d86982a92b09a505311426f123238a64b9157209b7f40ea400c24
crt-v0.4.0-preview.1-windows-03-gfx-simple-source.tar.xz	0.1 MB	c2bc57e28a698acbf5a093bf46c9dbd4200f92691b189e84a1d0037d529e0ce2
crt-v0.4.0-preview.1-windows-02-cxx-source.tar.xz	8.2 MB	f7a79cbec9a7c2684182f26286098cb66e9230748fc1676c223ef554bc87b38e

Most people need only the 04-gfx-media archive. The smaller stages are for
products that stop at C, C++, or the simple framebuffer. The *-source.tar.xz
files are the stage-source assets that the packaged stage recipes download
(pinned by size and SHA-256); you do not need them to use an SDK.
SHA256SUMS-windows-x86_64 lists every checksum above, and
release-manifest-windows-x86_64.json records the version, source commit, and
per-asset size and SHA-256.

macOS/arm64 (Apple Silicon)

Asset	Size	SHA-256
crt-v0.4.0-preview.1-macos-aarch64-04-gfx-media.tar.xz	14.1 MB	802422edfbb3b6798b6d10ec85089b4e9b173e3da9042f52942bdfdf274b14bd
crt-v0.4.0-preview.1-macos-aarch64-03-gfx-simple.tar.xz	4.9 MB	f1ec8058a5c93f838186a27d95eea863d8c372e0a8edb621112da894070d313b
crt-v0.4.0-preview.1-macos-aarch64-02-cxx.tar.xz	4.9 MB	09c2dab341d6ae9a7ca0e1fe3e895d22479dc2157ad2a1e4a223d5127ce5ea1c
crt-v0.4.0-preview.1-macos-aarch64-01-c.tar.xz	1.8 MB	83876183f0aa24fec1e451144b0b53510741d5f6c42188ea41f71aee64a06c2e
crt-v0.4.0-preview.1-macos-04-gfx-media-source.tar.xz	18.2 MB	4bf38b0d864358cce6a8e7d6d0551fe8ce7546dfd4e34faf37aa0188a966fb41
crt-v0.4.0-preview.1-macos-03-gfx-simple-source.tar.xz	0.1 MB	1cc81949ef052fabcd4a44c5a6fdf8c2b949bd47d093faa9745aefff897ec9aa
crt-v0.4.0-preview.1-macos-02-cxx-source.tar.xz	8.0 MB	1ebb577af42a60c6408eeaacae6b3dba93244bd254441c5e4d82a86bc0d2ec59

The same guidance applies: most people need only the 04-gfx-media archive, and
the *-source.tar.xz files are the stage-source assets the packaged recipes
download. SHA256SUMS-macos-aarch64 lists every checksum above, and
release-manifest-macos-aarch64.json records the version, source commit, and
per-asset size and SHA-256.

The macOS assets were built from a later commit than the tag. The tag
v0.4.0-preview.1 points at fd01d7c, which is what the Windows assets record.
The macOS manifest records 972d913, which is later than the tag (the two fixes
bel...