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torchcodec is PyTorch's video decoder: a scikit-build-core/CMake project that compiles a C++20 core against libtorch and FFmpeg, plus a separate, FFmpeg-free image-decoder library. Upstream links its wheels against prebuilt non-GPL FFmpeg tarballs it hosts on S3, which carry no riscv64 build, so the workflow takes the project's other supported path -- pkg-config against an installed FFmpeg -- and builds that FFmpeg from source in the container, LGPL and never shipped. FFmpeg 6.1 because the major version is baked into the libtorchcodec_core<N>.so name the Python loader dlopen()s, and 6.1 is what ubuntu-24.04-riscv ships. AVIF and HEIC image decoding are off: libavif comes from the same S3 bucket and libheif is packaged in neither Rocky 10 nor a riscv64 EPEL. JPEG, PNG, WebP and the vendored giflib are built as usual. Also records two reusable gotchas found along the way (383, 384).
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RPM installs %license files regardless of tsflags=nodocs (only %doc is dropped), and all four packages whose licences the wheel needs mark them %license -- confirmed against the CentOS Stream 10 spec files, which are also where `%files devel` confirms libwebp-devel ships the CMake package config find_package(WebP) needs. The reinstall stays as belt-and-braces but must not fail the build when a package is no longer available from a repo.
luhenry
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Restores skills/python-project-porting/references/{gotchas-index.md,
gotchas/local-validation-and-rehearsal.md, gotchas/native-deps-and-linking.md}
to main's current content. The two gotchas this PR had added (383/384,
torch+CUDA rehearsal and versioned-dlopen ABI contract) also collided with
gotcha numbers other agents had already taken on main in the meantime -
they'll be re-added on main directly with fresh numbers instead.
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These were originally added inside PR #2105 (torchcodec), which is not allowed to touch skills/ - removed from that branch and landed here instead, renumbered from their original 383/384 (already taken by other concurrent work by the time this was caught).
…is branch no longer touches # Conflicts: # skills/python-project-porting/references/gotchas-index.md # skills/python-project-porting/references/gotchas/local-validation-and-rehearsal.md
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torchcodec0.16.0Compiles PyTorch's video decoder: a C++20 core linked against libtorch and FFmpeg, plus a separate FFmpeg-free image-decoder library. Upstream publishes no riscv64 wheel.
Mirrors upstream's
linux_wheel.yaml.Differs from upstream
libtorchcodec_core6.somatches ubuntu-24.04-riscv's system FFmpeg.TORCHCODEC_BUILD_AVIF=0,TORCHCODEC_BUILD_HEIC=0- libavif comes from the same bucket, libheif is in neither Rocky 10 nor a riscv64 EPEL.Testing
torchvisionnot on the registry, sotest_transform_ops.pyis deselected.License: Wheel bundles libjpeg-turbo, libpng, zlib and libwebp (all permissive); upstream ships their licence texts from its own repair script, which this build does not use, so the build adds them.
Patches
0001-pyproject-glob-the-licence-texts-of-the-bundled-image.patch-Upstream-Status: Inappropriate. Without it PEP 639's explicitlicense-fileslist silently drops the vendored-library licence texts. Not riscv64-specific, but only meaningful for a plain-auditwheel repair.Not built locally: the manylinux riscv64 image is unreachable from this host, and an x86 rehearsal of a libtorch project needs a CPU-only torch that PyPI does not serve. First CI run is the first build.