aom build error on x64-windows with NASM 3.01: “Unsupported nasm: multipass optimization not supported”

Environment

OS: Windows 11 x64

vcpkg root: cloned from https://github.com/microsoft/vcpkg

Triplet: x64-windows

vcpkg version: (output of vcpkg version)

MSVC: 19.50.35723 (Visual Studio 2026 / v145 toolset)

CMake: 3.31.10

NASM (downloaded by vcpkg tools): 3.01

Repro steps

text
git clone https://github.com/microsoft/vcpkg.git
cd vcpkg
.\bootstrap-vcpkg.bat

vcpkg install aom:x64-windows
(Alternatively, the error appears when configuring a CMake project that depends on ffmpeg[aom,...]:x64-windows in manifest mode, which triggers vcpkg install for aom:x64-windows.)

Observed behavior

The build of aom:x64-windows fails during CMake configure.

From vcpkg\buildtrees\aom\config-x64-windows-out.log:

text
-- The ASM_NASM compiler identification is NASM
-- Found assembler: /downloads/tools/nasm/nasm-3.01/nasm.exe
CMake Error at build/cmake/aom_optimization.cmake:219 (message):
Unsupported nasm: multipass optimization not supported.
Call Stack (most recent call first):
build/cmake/aom_configure.cmake:172 (test_nasm)
CMakeLists.txt:73 (include)

-- Configuring incomplete, errors occurred!
ninja: build stopped: subcommand failed.
The CMake command that vcpkg runs for aom includes, among other options:

text
-DCMAKE_ASM_NASM_COMPILER=/downloads/tools/nasm/nasm-3.01/nasm.exe
-DVCPKG_PLATFORM_TOOLSET=v145
-G Ninja
So the port always picks up NASM 3.01 from downloads/tools, and the aom CMake scripts reject this NASM version.

Expected behavior

aom:x64-windows should configure and build successfully with the NASM version provided by vcpkg, or the port should pin/use a NASM version that is known to work with the current aom sources.

Questions / notes

Is NASM 3.01 officially supported by the current aom port on Windows?

Would it be possible for the port to:

either pin a known‑good NASM version, or

respect an externally provided CMAKE_ASM_NASM_COMPILER so users can point to a compatible NASM?

I’m happy to test any proposed changes or a pinned NASM version.

Reproduce the failure with vcpkg install aom:x64-windows, then inspect build/cmake/aom_optimization.cmake and build/cmake/aom_configure.cmake at the reported NASM check. Verify how the aom port selects NASM 3.01 and whether a compatible selection can be supported. Done means aom configures and builds successfully on x64-windows, or the supported NASM requirement is made explicit.