fix(build): skip avfft.h for FFmpeg >= 8 (removed upstream)

[gaurav02081]

Problem

libavcodec/avfft.h was deprecated in FFmpeg 6.0 (lavc 60.25.100) and
removed in FFmpeg 8.0. Building against FFmpeg ≥ 8 could fail depending
on include path resolution behavior.

The previous implementation relied on an exists() guard after
search_include, which depended on fallback filesystem behavior rather
than explicit version semantics.

Fixes #117.

---

Solution

• Gate inclusion of libavcodec/avfft.h on ffmpeg_major_version < 8
• Use the existing maybe_search_include helper for safe lookup
• Follow the same version-gating pattern already used for vaapi.h

This removes reliance on filesystem fallback behavior and makes the
intent explicit and consistent with existing header guards.

---

Testing

Tested on macOS with FFmpeg 8.0.1 (Homebrew):

• cargo build succeeds
• avfft.h is not included in bindgen output
• No avfft symbols appear in generated bindings.rs
• No regressions observed

This preserves compatibility for users building against older FFmpeg
versions while ensuring clean builds with FFmpeg 8+.

[selvmaya]

Any known workarounds for this? For reference, I am trying to compile https://github.com/russelltg/wl-screenrec

[gaurav02081]

Any known workarounds for this? For reference, I am trying to compile https://github.com/russelltg/wl-screenrec

Until this PR is merged, you can work around it by using my fork directly. In the Cargo.toml of wl-screenrec (or wherever ffmpeg-sys-next is depended on), add
a git override:

[patch.crates-io]
ffmpeg-sys-next = { git = "https://github.com/gaurav02081/rust-ffmpeg-sys", branch = "gaurav-v1" }

This will use the patched build.rs that skips avfft.h on FFmpeg >= 8.

[selvmaya]

Unfortunately, I keep running into this obscure compilation error:

I'm not sure where to go from here. I am on up to date standard x86_64 Arch Linux, with the newest ffmpeg 8.1.3 (as well as 4.4 for some dependents).

Also, if I check the package without --release, this debug assert additionally fails:

Is my machine target specification malformed somehow?

[gaurav02081]

Unfortunately, I keep running into this obscure compilation error: I'm not sure where to go from here. I am on up to date standard x86_64 Arch Linux, with the newest ffmpeg 8.1.3 (as well as 4.4 for some dependents).

Also, if I check the package without --release, this debug assert additionally fails: Is my machine target specification malformed somehow?

---

seems like the issue is with your clang/bindgen setup.

Try setting this before building: export BINDGEN_EXTRA_CLANG_ARGS="--target=x86_64-unknown-linux-gnu -D__float128='long double'"

This should fix both the __float128 error and the pointer width mismatch (4 vs 8).
If that doesn't work, make sure you have the 64-bit clang installed.

sudo pacman -S clang

[selvmaya]

Try setting this before building: export BINDGEN_EXTRA_CLANG_ARGS="--target=x86_64-unknown-linux-gnu -D__float128='long double'"

$env.BINDGEN_EXTRA_CLANG_ARGS = "--target=x86_64-unknown-linux-gnu -D__float128='long double'"

This fixed the compilation issue :)
Leaving my fork here for anyone with the same issue in the meantime (I also made ffmpeg-sys-next use the 2024 edition, since it was unspecified): https://github.com/selvmaya/wl-screenrec

Unfortunately it seems my nvidia+intel laptop does not want to use libva/vaapi, but that's another issue.

vaapi errors

After installing libva-nvidia-driver: