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improved dynamic linking #139

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Merged
merged 5 commits into from
Aug 16, 2025
+57 −18
Merged

improved dynamic linking #139

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e8d9c28
try setup dynamic linking
TroyKomodo Jun 28, 2025
b1605cc
fix typos
TroyKomodo Jun 28, 2025
cca349e
fix order
TroyKomodo Jun 28, 2025
e7e2bc2
fix fmt and windows
TroyKomodo Aug 15, 2025
267c225
add new env variable to build script rerun
TroyKomodo Aug 15, 2025
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75 changes: 57 additions & 18 deletions build.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -242,18 +242,31 @@ fn generate_bindings(ffmpeg_include_dir: &Path, headers: &[PathBuf]) -> Bindings
.expect("Binding generation failed.")
}

fn static_linking_with_libs_dir(library_names: &[&str], ffmpeg_libs_dir: &Path) {
println!("cargo:rustc-link-search=native={}", ffmpeg_libs_dir);
fn linking_with_libs_dir(library_names: &[&str], ffmpeg_libs_dir: &Path, mode: FfmpegLinkMode) {
println!("cargo:rustc-link-search=native={ffmpeg_libs_dir}");
for library_name in library_names {
println!("cargo:rustc-link-lib=static={}", library_name);
println!(
"cargo:rustc-link-lib={}={library_name}",
match mode {
FfmpegLinkMode::Dynamic => "dylib",
FfmpegLinkMode::Static => "static",
}
);
}
}

#[derive(Clone, Copy)]
enum FfmpegLinkMode {
Static,
Dynamic,
}

#[allow(dead_code)]
pub struct EnvVars {
docs_rs: Option<String>,
out_dir: Option<PathBuf>,
ffmpeg_include_dir: Option<PathBuf>,
ffmpeg_link_mode: Option<FfmpegLinkMode>,
ffmpeg_dll_path: Option<PathBuf>,
ffmpeg_pkg_config_path: Option<PathBuf>,
ffmpeg_libs_dir: Option<PathBuf>,
Expand All @@ -269,6 +282,7 @@ impl EnvVars {
println!("cargo:rerun-if-env-changed=FFMPEG_PKG_CONFIG_PATH");
println!("cargo:rerun-if-env-changed=FFMPEG_LIBS_DIR");
println!("cargo:rerun-if-env-changed=FFMPEG_BINDING_PATH");
println!("cargo:rerun-if-env-changed=FFMPEG_LINK_MODE");
Self {
docs_rs: env::var("DOCS_RS").ok(),
out_dir: env::var("OUT_DIR").ok().map(remove_verbatim),
Expand All @@ -277,6 +291,12 @@ impl EnvVars {
ffmpeg_pkg_config_path: env::var("FFMPEG_PKG_CONFIG_PATH").ok().map(remove_verbatim),
ffmpeg_libs_dir: env::var("FFMPEG_LIBS_DIR").ok().map(remove_verbatim),
ffmpeg_binding_path: env::var("FFMPEG_BINDING_PATH").ok().map(remove_verbatim),
ffmpeg_link_mode: match env::var("FFMPEG_LINK_MODE").ok().as_deref() {
Some("static") => Some(FfmpegLinkMode::Static),
Some("dynamic") => Some(FfmpegLinkMode::Dynamic),
Some(r) => panic!("invalid FFMPEG_LINK_MODE value {r}, expected [static,dynamic]"),
None => None,
},
}
}
}
Expand Down Expand Up @@ -359,8 +379,18 @@ mod vcpkg_linking {
}
}

fn dynamic_linking(env_vars: &EnvVars) {
fn dynamic_linking(mut env_vars: EnvVars) {
let ffmpeg_dll_path = env_vars.ffmpeg_dll_path.as_ref().unwrap();
if ffmpeg_dll_path.is_dir() {
if env_vars.ffmpeg_libs_dir.is_none() {
env_vars.ffmpeg_libs_dir = Some(ffmpeg_dll_path.clone());
}
if env_vars.ffmpeg_link_mode.is_none() {
env_vars.ffmpeg_link_mode = Some(FfmpegLinkMode::Dynamic);
}

return linking(env_vars);
}

let output_binding_path = &env_vars.out_dir.as_ref().unwrap().join("binding.rs");

Expand Down Expand Up @@ -396,12 +426,12 @@ fn dynamic_linking(env_vars: &EnvVars) {
}
}

fn static_linking(env_vars: &EnvVars) {
fn linking(env_vars: EnvVars) {
let output_binding_path = &env_vars.out_dir.as_ref().unwrap().join("binding.rs");

#[cfg(not(target_os = "windows"))]
{
fn static_linking_with_pkg_config_and_bindgen(
fn linking_with_pkg_config_and_bindgen(
env_vars: &EnvVars,
output_binding_path: &Path,
) -> Result<(), pkg_config::Error> {
Expand Down Expand Up @@ -430,10 +460,14 @@ fn static_linking(env_vars: &EnvVars) {
);
}
env::set_var("PKG_CONFIG_PATH", ffmpeg_pkg_config_path);
static_linking_with_pkg_config_and_bindgen(env_vars, output_binding_path)
linking_with_pkg_config_and_bindgen(&env_vars, output_binding_path)
.expect("Static linking with pkg-config failed.");
} else if let Some(ffmpeg_libs_dir) = env_vars.ffmpeg_libs_dir.as_ref() {
static_linking_with_libs_dir(&*LIBS, ffmpeg_libs_dir);
linking_with_libs_dir(
&*LIBS,
ffmpeg_libs_dir,
env_vars.ffmpeg_link_mode.unwrap_or(FfmpegLinkMode::Static),
);
if let Some(ffmpeg_binding_path) = env_vars.ffmpeg_binding_path.as_ref() {
use_prebuilt_binding(ffmpeg_binding_path, output_binding_path);
} else if let Some(ffmpeg_include_dir) = env_vars.ffmpeg_include_dir.as_ref() {
Expand All @@ -460,7 +494,7 @@ Enable `link_vcpkg_ffmpeg` feature if you want to link ffmpeg libraries installe
#[cfg(feature = "link_system_ffmpeg")]
if !success {
if let Err(e) =
static_linking_with_pkg_config_and_bindgen(env_vars, output_binding_path)
linking_with_pkg_config_and_bindgen(&env_vars, output_binding_path)
{
error.push('\n');
error.push_str(&format!("Link system FFmpeg failed: {:?}", e));
Expand All @@ -471,9 +505,10 @@ Enable `link_vcpkg_ffmpeg` feature if you want to link ffmpeg libraries installe
}
#[cfg(feature = "link_vcpkg_ffmpeg")]
if !success {
if let Err(e) =
vcpkg_linking::linking_with_vcpkg_and_bindgen(env_vars, output_binding_path)
{
if let Err(e) = vcpkg_linking::linking_with_vcpkg_and_bindgen(
&env_vars,
output_binding_path,
) {
error.push('\n');
error.push_str(&format!("Link vcpkg FFmpeg failed: {:?}", e));
} else {
Expand All @@ -490,7 +525,11 @@ Enable `link_vcpkg_ffmpeg` feature if you want to link ffmpeg libraries installe
#[cfg(target_os = "windows")]
{
if let Some(ffmpeg_libs_dir) = env_vars.ffmpeg_libs_dir.as_ref() {
static_linking_with_libs_dir(&*LIBS, ffmpeg_libs_dir);
linking_with_libs_dir(
&*LIBS,
ffmpeg_libs_dir,
env_vars.ffmpeg_link_mode.unwrap_or(FfmpegLinkMode::Static),
);
if let Some(ffmpeg_binding_path) = env_vars.ffmpeg_binding_path.as_ref() {
use_prebuilt_binding(ffmpeg_binding_path, output_binding_path);
} else if let Some(ffmpeg_include_dir) = env_vars.ffmpeg_include_dir.as_ref() {
Expand All @@ -502,7 +541,7 @@ Enable `link_vcpkg_ffmpeg` feature if you want to link ffmpeg libraries installe
}
} else {
#[cfg(feature = "link_vcpkg_ffmpeg")]
vcpkg_linking::linking_with_vcpkg_and_bindgen(env_vars, output_binding_path)
vcpkg_linking::linking_with_vcpkg_and_bindgen(&env_vars, output_binding_path)
.expect("Linking FFmpeg with vcpkg failed.");
#[cfg(not(feature = "link_vcpkg_ffmpeg"))]
panic!(
Expand All @@ -516,7 +555,7 @@ Enable `link_vcpkg_ffmpeg` feature if you want to link ffmpeg provided by vcpkg.
}
}

fn docs_rs_linking(env_vars: &EnvVars) {
fn docs_rs_linking(env_vars: EnvVars) {
// If it's a documentation generation from docs.rs, just copy the bindings
// generated locally to `OUT_DIR`. We do this because the building
// environment of docs.rs doesn't have an network connection, so we cannot
Expand All @@ -531,11 +570,11 @@ fn docs_rs_linking(env_vars: &EnvVars) {
fn main() {
let env_vars = EnvVars::init();
if env_vars.docs_rs.is_some() {
docs_rs_linking(&env_vars);
docs_rs_linking(env_vars);
} else if env_vars.ffmpeg_dll_path.is_some() {
dynamic_linking(&env_vars);
dynamic_linking(env_vars);
} else {
// fallback to static linking
static_linking(&env_vars);
linking(env_vars);
}
}
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