pyav 是如何调用 FFmpeg libraries 的？

我知道，python 脚本可以调用 c 的 .so 文件

有一个包：pyav，用于处理音视频的包

PyAV is a Pythonic binding for the FFmpeg libraries. We aim to provide all of the power and control of the underlying library, but manage the gritty details as much as possible.

根据 README.md 的说明，使用了 FFmpeg libraries

但是，我搜索 ~/.local/share/virtualenvs/svddb_testing-LBS8tSMB/lib/python3.10/site-packages 路径下的 so 文件，没有带 FFmpeg 字样的 so 文件

─➤  fd -u -e .so                                                                                                                                                                                                                                            1 ↵
PIL/_imaging.cpython-310-darwin.so
PIL/_imagingcms.cpython-310-darwin.so
PIL/_imagingft.cpython-310-darwin.so
PIL/_imagingmath.cpython-310-darwin.so
PIL/_imagingmorph.cpython-310-darwin.so
PIL/_imagingtk.cpython-310-darwin.so
PIL/_webp.cpython-310-darwin.so
_cffi_backend.cpython-310-darwin.so
av/_core.cpython-310-darwin.so
av/audio/codeccontext.cpython-310-darwin.so
av/audio/fifo.cpython-310-darwin.so
av/audio/format.cpython-310-darwin.so
av/audio/frame.cpython-310-darwin.so
av/audio/layout.cpython-310-darwin.so
av/audio/plane.cpython-310-darwin.so
av/audio/resampler.cpython-310-darwin.so
av/audio/stream.cpython-310-darwin.so
av/buffer.cpython-310-darwin.so
av/bytesource.cpython-310-darwin.so
av/codec/codec.cpython-310-darwin.so
av/codec/context.cpython-310-darwin.so
av/container/core.cpython-310-darwin.so
av/container/input.cpython-310-darwin.so
av/container/output.cpython-310-darwin.so
av/container/pyio.cpython-310-darwin.so
av/container/streams.cpython-310-darwin.so
av/data/stream.cpython-310-darwin.so
av/descriptor.cpython-310-darwin.so
av/dictionary.cpython-310-darwin.so
av/enum.cpython-310-darwin.so
av/error.cpython-310-darwin.so
av/filter/context.cpython-310-darwin.so
av/filter/filter.cpython-310-darwin.so
av/filter/graph.cpython-310-darwin.so
av/filter/link.cpython-310-darwin.so
av/filter/pad.cpython-310-darwin.so
av/format.cpython-310-darwin.so
av/frame.cpython-310-darwin.so
av/logging.cpython-310-darwin.so
av/option.cpython-310-darwin.so
av/packet.cpython-310-darwin.so
av/plane.cpython-310-darwin.so
av/sidedata/motionvectors.cpython-310-darwin.so
av/sidedata/sidedata.cpython-310-darwin.so
av/stream.cpython-310-darwin.so
av/subtitles/codeccontext.cpython-310-darwin.so
av/subtitles/stream.cpython-310-darwin.so
av/subtitles/subtitle.cpython-310-darwin.so
av/utils.cpython-310-darwin.so
av/video/codeccontext.cpython-310-darwin.so
av/video/format.cpython-310-darwin.so
av/video/frame.cpython-310-darwin.so
av/video/plane.cpython-310-darwin.so
av/video/reformatter.cpython-310-darwin.so
av/video/stream.cpython-310-darwin.so
charset_normalizer/md.cpython-310-darwin.so
charset_normalizer/md__mypyc.cpython-310-darwin.so
cryptography/hazmat/bindings/_openssl.abi3.so
cryptography/hazmat/bindings/_rust.abi3.so
cv2/cv2.abi3.so
numpy/core/_multiarray_tests.cpython-310-darwin.so
numpy/core/_multiarray_umath.cpython-310-darwin.so
numpy/core/_operand_flag_tests.cpython-310-darwin.so
numpy/core/_rational_tests.cpython-310-darwin.so
numpy/core/_simd.cpython-310-darwin.so
numpy/core/_struct_ufunc_tests.cpython-310-darwin.so
numpy/core/_umath_tests.cpython-310-darwin.so
numpy/fft/_pocketfft_internal.cpython-310-darwin.so
numpy/linalg/_umath_linalg.cpython-310-darwin.so
numpy/linalg/lapack_lite.cpython-310-darwin.so
numpy/random/_bounded_integers.cpython-310-darwin.so
numpy/random/_common.cpython-310-darwin.so
numpy/random/_generator.cpython-310-darwin.so
numpy/random/_mt19937.cpython-310-darwin.so
numpy/random/_pcg64.cpython-310-darwin.so
numpy/random/_philox.cpython-310-darwin.so
numpy/random/_sfc64.cpython-310-darwin.so
numpy/random/bit_generator.cpython-310-darwin.so
numpy/random/mtrand.cpython-310-darwin.so
psutil/_psutil_osx.abi3.so
psutil/_psutil_posix.abi3.so
pydantic/__init__.cpython-310-darwin.so
pydantic/_hypothesis_plugin.cpython-310-darwin.so
pydantic/annotated_types.cpython-310-darwin.so
pydantic/class_validators.cpython-310-darwin.so
pydantic/color.cpython-310-darwin.so
pydantic/config.cpython-310-darwin.so
pydantic/dataclasses.cpython-310-darwin.so
pydantic/datetime_parse.cpython-310-darwin.so
pydantic/decorator.cpython-310-darwin.so
pydantic/env_settings.cpython-310-darwin.so
pydantic/error_wrappers.cpython-310-darwin.so
pydantic/errors.cpython-310-darwin.so
pydantic/fields.cpython-310-darwin.so
pydantic/json.cpython-310-darwin.so
pydantic/main.cpython-310-darwin.so
pydantic/mypy.cpython-310-darwin.so
pydantic/networks.cpython-310-darwin.so
pydantic/parse.cpython-310-darwin.so
pydantic/schema.cpython-310-darwin.so
pydantic/tools.cpython-310-darwin.so
pydantic/types.cpython-310-darwin.so
pydantic/typing.cpython-310-darwin.so
pydantic/utils.cpython-310-darwin.so
pydantic/validators.cpython-310-darwin.so
pydantic/version.cpython-310-darwin.so
torch/_C.cpython-310-darwin.so
torch/_C_flatbuffer.cpython-310-darwin.so
torch/_dl.cpython-310-darwin.so
torchvision/_C.so
torchvision/image.so
yaml/_yaml.cpython-310-darwin.so

为什么呢？是因为 FFmpeg libraries 的 so 文件，不带 FFmpeg 字样？

我发现，我的电脑不装 FFmpeg 这个 app，pyav 也是可能正常工作的，所以这个 pyav 应该是不依赖 FFmpeg 这个 app，可能只是依赖 FFmpeg 的某个 so 文件？