FFmpeg software H.264 decoder: opt-in via pubspec flag

- Gate buildFfmpegJni + jniLibs packaging on `ux: enable_ffmpeg` in the
  consuming app's pubspec (default off) -- no LGPL / H.264-patent
  exposure unless explicitly enabled
- appInfoBuilder generates kUxEnableFfmpeg from the same flag so apps
  register the FFmpeg LGPL notice eagerly, pubspec-only (no dart-define)
- Add registerFfmpegLicense() + bundled LGPL-2.1 text asset
- FFmpeg compliance docs (LICENSES-3RDPARTY.md, android/ffmpeg/README.md)
- Network video streaming: XVideoPlayerController.network

LICENSES-3RDPARTY.md

@@ -0,0 +1,76 @@
+# ux — Third-Party Licenses & Compliance
+
+`ux` can bundle one component with distribution obligations: **FFmpeg**, used
+as a software H.264 video decoder on Android. It is **opt-in and disabled by
+default** — only apps that enable it ship it and inherit the obligation:
+
+```yaml
+ux:
+  enable_ffmpeg: true
+```
+
+That pubspec flag is the single source of truth: Gradle reads it for the
+native build, and ux's build_runner builder generates a `kUxEnableFfmpeg`
+constant from it into the app's `app_info.g.dart`, which gates
+`registerFfmpegLicense()` at startup — so the in-app LGPL notice follows
+automatically, eagerly, with no `--dart-define`.
+
+Apps that enable it need to (a) surface a license UI and (b) be able to honor
+the source offer below; apps that leave it disabled have no FFmpeg obligation
+(and the in-app notice never appears).
+
+## FFmpeg (LGPL-2.1) — Android only
+
+### What and where
+Compiled from source into `libffmpegJNI.so` per ABI and loaded at runtime via
+`System.loadLibrary` — an ExoPlayer/Media3 fallback **decode-only** renderer.
+Not a pub/Dart dependency. iOS/macOS use AVFoundation → **no FFmpeg, no
+obligation** there.
+
+- Build wiring: [android/ffmpeg/](android/ffmpeg/) — `build_ffmpeg.sh`,
+  `CMakeLists.txt`, `ffmpeg_jni.cc`, `README.md`, `LICENSE-FFMPEG.txt`.
+- Attribution: [lib/builder.dart](lib/builder.dart) generates a
+  `kUxEnableFfmpeg` constant from the app's `ux: enable_ffmpeg` pubspec flag
+  into `app_info.g.dart`; the app gates
+  [registerFfmpegLicense()](lib/src/video/ffmpeg_license.dart) on it at
+  startup (`if (kUxEnableFfmpeg) registerFfmpegLicense();`). So a build with
+  the flag off registers nothing, and an enabled build shows the notice
+  eagerly. Idempotent.
+- Bundled LGPL text asset: `assets/licenses/ffmpeg_LGPL-2.1.txt`.
+
+### Versions (pinned)
+- FFmpeg **`release/6.0`** (upstream `git.ffmpeg.org`)
+- Media3 **`1.9.2`** (JNI/renderer skeleton)
+
+### License posture
+- **LGPL v2.1**, dynamic boundary (separate, replaceable `.so`) → **no
+  copyleft on the consuming app**.
+- Built **decode-only** (H.264 decoder, **no encoders**) and **WITHOUT
+  `--enable-gpl` / `--enable-nonfree`** → **LGPL-only**. See `build_ffmpeg.sh`.
+
+### How we comply (LGPL-2.1)
+1. **Attribution + license text** — registered via `registerFfmpegLicense()`,
+   shown in any consuming app's license UI. ✅
+2. **Corresponding source** — we make the FFmpeg `release/6.0` source **plus
+   the build/link scripts** (`build_ffmpeg.sh`, `CMakeLists.txt`,
+   `ffmpeg_jni.cc`) available **on request for ≥3 years**. **This does NOT
+   include the application's own source code** — only the LGPL library and the
+   scripts that compile/link it. Contact: **alex@swipelab.co**.
+   → *Each release: archive the matching FFmpeg source tarball + the scripts.*
+3. **Relink right (LGPL §6)** — `libffmpegJNI.so` is a standalone,
+   user-rebuildable shared library; sources + script are here, so a modified
+   FFmpeg can be rebuilt and swapped in. ✅
+4. **Do not taint** — never add `--enable-gpl` / `--enable-nonfree` or
+   GPL-only codecs (x264, x265, …).
+
+### Patent note (for legal — separate from copyright)
+FFmpeg's H.264 *decoder code* is LGPL, but the **H.264/AVC standard** is
+patent-encumbered (Via LA pool, formerly MPEG-LA). We ship a **software AVC
+decoder** — a patent/commercial matter for counsel, **not** an open-source or
+store-policy issue. Exposure is limited to **decode** (no encoder shipped).
+
+## Release checklist
+- [ ] FFmpeg/Media3 tags unchanged, or doc + archived source updated if bumped.
+- [ ] Build still omits `--enable-gpl` / `--enable-nonfree`; decode-only.
+- [ ] `registerFfmpegLicense()` reachable (auto on video, or eager at startup).
+- [ ] FFmpeg `release/6.0` source tarball + scripts archived for this version.

android/build.gradle

@@ -24,9 +24,59 @@ rootProject.allprojects {
 apply plugin: 'com.android.library'
 apply plugin: 'kotlin-android'
 
+// FFmpeg software H.264 decoder — OPT-IN, disabled by default.
+//
+// The decoder (a fallback for devices whose hardware decoder fails) carries
+// LGPL + H.264 patent obligations, so it is only bundled when the consuming
+// app asks for it, via a flag in its pubspec.yaml:
+//
+//     ux:
+//       enable_ffmpeg: true
+//
+// (or -Pux.enable_ffmpeg=true on the Gradle command line as a CI override).
+// When off: buildFfmpegJni is skipped, no libffmpegJNI.so is packaged,
+// FfmpegLibrary.isAvailable() returns false, the renderer is never added, and
+// playback uses the platform MediaCodec decoders only. See android/ffmpeg/README.md.
+//
+// This pubspec flag is the only switch: ux's build_runner builder also reads
+// `ux: enable_ffmpeg` and generates a `kUxEnableFfmpeg` constant the app uses
+// to register the LGPL license notice — no --dart-define needed.
+def ffmpegEnabled = {
+    // CI / command-line override takes precedence over the pubspec flag.
+    def prop = project.findProperty('ux.enable_ffmpeg')
+    if (prop != null) return prop.toString().trim().equalsIgnoreCase('true')
+
+    // rootProject is the consuming app's android/ project; its pubspec.yaml
+    // sits one directory up. Match a top-level `ux:` block (not the indented
+    // `ux:` dependency entry) and its nested `enable_ffmpeg:` value.
+    def pubspec = new File(rootProject.projectDir.parentFile, 'pubspec.yaml')
+    if (!pubspec.exists()) return false
+    boolean inUxBlock = false
+    boolean enabled = false
+    pubspec.eachLine { raw ->
+        def hash = raw.indexOf('#')
+        def line = hash >= 0 ? raw.substring(0, hash) : raw
+        if (line.trim().isEmpty()) return
+        if (!Character.isWhitespace(line.charAt(0))) {
+            // A new top-level key: we're in the config block only if it's `ux:`.
+            inUxBlock = line.trim().startsWith('ux:')
+        } else if (inUxBlock) {
+            def t = line.trim()
+            if (t.startsWith('enable_ffmpeg:')) {
+                enabled = t.substring('enable_ffmpeg:'.length()).trim().equalsIgnoreCase('true')
+            }
+        }
+    }
+    return enabled
+}()
+
 android {
     namespace 'io.swipelab.ux'
-    compileSdk 34
+    // media3 1.9.2 requires compileSdk >= 35; match the app/Flutter default (36).
+    compileSdk 36
+    // Match Flutter's pinned NDK (flutter_tools gradle_utils.dart) and the
+    // app; AGP 8.1's default NDK (25.x) isn't installed on dev machines.
+    ndkVersion '28.2.13676358'
 
     defaultConfig {
         minSdk 21
@@ -55,21 +105,23 @@ android {
     sourceSets {
         main {
             // libffmpegJNI.so is built by the buildFfmpegJni task into
-            // build/jniLibs/<abi>/ on first build (and any time the
+            // build/jniLibs/<abi>/. Only reference it when FFmpeg is enabled,
-            // vendored ffmpeg_jni.cc / CMakeLists.txt change). Adding
+            // so a stale .so from a previous enabled build is not packaged
-            // the directory here lets AGP package the .so into the
+            // into a now-disabled build. Lets AGP package the .so into the
             // AAR without committing native binaries to the repo.
-            jniLibs.srcDirs += "$buildDir/jniLibs"
+            if (ffmpegEnabled) {
+                jniLibs.srcDirs += "$buildDir/jniLibs"
+            }
         }
     }
 }
 
-// FFmpeg video decoder build — runs as part of the normal Android
+// FFmpeg video decoder build (opt-in — see the `ffmpegEnabled` flag near the
-// build. On first build for a given checkout it clones Media3 + FFmpeg
+// top of this file and android/ffmpeg/README.md). When enabled, the first
-// into build/ffmpeg-work/ and produces libffmpegJNI.so per ABI (~30 min
+// build for a checkout clones Media3 + FFmpeg into build/ffmpeg-work/ and
-// for the FFmpeg static-lib step the first time, fast after). Gradle
+// produces libffmpegJNI.so per ABI (~30 min for the FFmpeg static-lib step the
-// UP-TO-DATE checking skips the task whenever the vendored JNI source
+// first time, fast after); Gradle UP-TO-DATE checking skips it when the
-// + CMakeLists are unchanged. See android/ffmpeg/README.md.
+// vendored JNI source + CMakeLists are unchanged.
 def ffmpegSrcDir = file("$projectDir/ffmpeg")
 def ffmpegWorkDir = file("$buildDir/ffmpeg-work")
 def ffmpegOutDir = file("$buildDir/jniLibs")
@@ -97,7 +149,13 @@ task buildFfmpegJni(type: Exec) {
 }
 
 afterEvaluate {
-    preBuild.dependsOn buildFfmpegJni
+    if (ffmpegEnabled) {
+        preBuild.dependsOn buildFfmpegJni
+        logger.lifecycle("ux: FFmpeg software H.264 decoder ENABLED (ux: enable_ffmpeg: true).")
+    } else {
+        logger.lifecycle("ux: FFmpeg software H.264 decoder disabled (default). " +
+            "Add 'ux:\\n  enable_ffmpeg: true' to the app pubspec.yaml to bundle it.")
+    }
 }
 
 dependencies {

android/ffmpeg/README.md

@@ -7,13 +7,34 @@ slotted ahead of `MediaCodecVideoRenderer` so iOS H.264 streams with
 deep DPB (`has_b_frames > 8`) and full-range YUV play on devices where
 the platform decoder fails (notably Huawei Mate 20 on EMUI 11).
 
+## Opt-in
+
+FFmpeg is **disabled by default** (it carries LGPL + H.264 patent
+obligations). A consuming app enables it with a flag in its `pubspec.yaml`:
+
+```yaml
+ux:
+  enable_ffmpeg: true
+```
+
+(or `-Pux.enable_ffmpeg=true` on the Gradle command line as a CI override).
+When disabled, no `libffmpegJNI.so` is built or packaged, `FfmpegLibrary
+.isAvailable()` returns false, the renderer is never added, and playback
+uses the platform MediaCodec decoders only.
+
+The pubspec flag is the **only** switch. The in-app LGPL license notice
+follows automatically: ux's build_runner builder ([lib/builder.dart](../../lib/builder.dart))
+reads `ux: enable_ffmpeg` from the app's pubspec and generates
+`kUxEnableFfmpeg` into the app's `app_info.g.dart`; the app gates
+`registerFfmpegLicense()` on that constant at startup. No `--dart-define`, no
+duplication — and the notice shows without needing to play a video.
+
 ## How it builds
 
-The native library is produced by the `:ux:buildFfmpegJni` Gradle task,
+When enabled, the native library is produced by the `:ux:buildFfmpegJni`
-wired as a dependency of `preBuild`. On any consumer build
+Gradle task, wired as a dependency of `preBuild`. The task runs on a
-(`flutter build apk`, `./gradlew assembleRelease`, IDE sync) the task
+consumer build (`flutter build apk`, `./gradlew assembleRelease`, IDE
-runs automatically; Gradle's UP-TO-DATE checking skips it when nothing
+sync); Gradle's UP-TO-DATE checking skips it when nothing relevant changed.
-relevant changed.
 
 What the task does:
 

assets/licenses/ffmpeg_LGPL-2.1.txt

@@ -0,0 +1,502 @@
+                  GNU LESSER GENERAL PUBLIC LICENSE
+                       Version 2.1, February 1999
+
+ Copyright (C) 1991, 1999 Free Software Foundation, Inc.
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+[This is the first released version of the Lesser GPL.  It also counts
+ as the successor of the GNU Library Public License, version 2, hence
+ the version number 2.1.]
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+possible use to the public, we recommend making it free software that
+everyone can redistribute and change.  You can do so by permitting
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+  To apply these terms, attach the following notices to the library.  It is
+safest to attach them to the start of each source file to most effectively
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+
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+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+    Lesser General Public License for more details.
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+
+  <signature of Ty Coon>, 1 April 1990
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+
+That's all there is to it!

example/pubspec.lock

@@ -343,10 +343,10 @@ packages:
     dependency: transitive
     description:
       name: matcher
-      sha256: dc0b7dc7651697ea4ff3e69ef44b0407ea32c487a39fff6a4004fa585e901861
+      sha256: "12956d0ad8390bbcc63ca2e1469c0619946ccb52809807067a7020d57e647aa6"
       url: "https://pub.dev"
     source: hosted
-    version: "0.12.19"
+    version: "0.12.18"
   material_color_utilities:
     dependency: transitive
     description:
@@ -484,10 +484,10 @@ packages:
     dependency: transitive
     description:
       name: test_api
-      sha256: "8161c84903fd860b26bfdefb7963b3f0b68fee7adea0f59ef805ecca346f0c7a"
+      sha256: "93167629bfc610f71560ab9312acdda4959de4df6fac7492c89ff0d3886f6636"
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.10"
+    version: "0.7.9"
   timing:
     dependency: transitive
     description:

lib/builder.dart

@@ -22,6 +22,8 @@ class _AppInfoBuilder implements Builder {
     final buildNumber =
         plus < 0 ? 0 : int.tryParse(combined.substring(plus + 1)) ?? 0;
 
+    final enableFfmpeg = _readUxFlag(raw, 'enable_ffmpeg');
+
     await buildStep.writeAsString(
       AssetId(pkg, 'lib/app_info.g.dart'),
       '''
@@ -29,7 +31,35 @@ class _AppInfoBuilder implements Builder {
 import 'package:ux/ux.dart';
 
 const kAppInfo = AppInfo(version: '$version', buildNumber: $buildNumber);
+
+/// Mirrors the app's `ux: enable_ffmpeg` pubspec setting as a compile-time
+/// constant. Gate FFmpeg-dependent code (e.g. registerFfmpegLicense()) on
+/// this — pubspec stays the single source of truth.
+const kUxEnableFfmpeg = $enableFfmpeg;
 ''',
     );
   }
+
+  /// Reads a boolean under the top-level `ux:` mapping, e.g. `ux: { $key: ... }`.
+  /// Scans manually (no YAML dep) and ignores the indented `ux:` dependency
+  /// entry by only entering the block on a non-indented `ux:` line.
+  static bool _readUxFlag(String pubspec, String key) {
+    var inUxBlock = false;
+    var enabled = false;
+    for (final rawLine in pubspec.split('\n')) {
+      final hash = rawLine.indexOf('#');
+      final line = hash >= 0 ? rawLine.substring(0, hash) : rawLine;
+      if (line.trim().isEmpty) continue;
+      final indented = line.startsWith(' ') || line.startsWith('\t');
+      if (!indented) {
+        inUxBlock = line.trimRight() == 'ux:' || line.startsWith('ux:');
+      } else if (inUxBlock) {
+        final t = line.trim();
+        if (t.startsWith('$key:')) {
+          enabled = t.substring(key.length + 1).trim().toLowerCase() == 'true';
+        }
+      }
+    }
+    return enabled;
+  }
 }

lib/src/video/ffmpeg_license.dart

@@ -0,0 +1,64 @@
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart' show rootBundle;
+
+/// Whether the FFmpeg notice has already been added to [LicenseRegistry].
+/// Registration adds a stream provider, so guard against duplicates.
+bool _registered = false;
+
+/// Registers the FFmpeg LGPL-2.1 attribution with [LicenseRegistry].
+///
+/// Call this at startup gated on the generated `kUxEnableFfmpeg` constant
+/// (from `app_info.g.dart`, which the ux build_runner builder derives from the
+/// app's `ux: enable_ffmpeg` pubspec flag) — e.g.
+/// `if (kUxEnableFfmpeg) registerFfmpegLicense();`. That keeps pubspec the
+/// single source of truth, registers eagerly (the notice shows without playing
+/// a video), and needs no `--dart-define`. Idempotent — registers at most once.
+void registerFfmpegLicense() {
+  if (_registered) return;
+  _registered = true;
+  LicenseRegistry.addLicense(_ffmpegLicenseEntries);
+}
+
+/// Attribution shown above the LGPL text. Keep in sync with
+/// `android/ffmpeg/build_ffmpeg.sh` (`FFMPEG_TAG`) and
+/// `android/ffmpeg/README.md`.
+const String _attribution = '''
+This application includes FFmpeg, used unmodified as a software video
+decoder on Android via the "ux" package (libffmpegJNI.so, loaded at runtime).
+
+FFmpeg is copyright (c) the FFmpeg developers and is licensed under the
+GNU Lesser General Public License, version 2.1 (LGPL-2.1). The binary is
+dynamically loaded by the app; the LGPL boundary is preserved and no
+copyleft is imposed on the application.
+
+Version: FFmpeg release/6.0, built from upstream source with the H.264
+decoder enabled only (decode-only, no encoders). It is configured WITHOUT
+--enable-gpl and WITHOUT --enable-nonfree, so the binary is LGPL-only.
+
+The corresponding FFmpeg source and the build/link scripts (which document
+the exact configure flags) are available on request for at least three
+years; the application's own source code is not included in that offer.
+The shared library can be rebuilt and replaced from those sources, as
+required by section 6 of the LGPL. Contact: alex@swipelab.co
+
+The full text of the LGPL v2.1 follows.''';
+
+Stream<LicenseEntry> _ffmpegLicenseEntries() async* {
+  String lgpl;
+  try {
+    lgpl = await rootBundle
+        .loadString('packages/ux/assets/licenses/ffmpeg_LGPL-2.1.txt');
+  } catch (error, stack) {
+    // A missing asset must never break license collection; the attribution
+    // paragraph below still names FFmpeg and its license.
+    FlutterError.reportError(
+      FlutterErrorDetails(exception: error, stack: stack),
+    );
+    lgpl = '';
+  }
+
+  yield LicenseEntryWithLineBreaks(
+    const <String>['FFmpeg (libavcodec, libavutil, libswresample)'],
+    lgpl.isEmpty ? _attribution : '$_attribution\n\n$lgpl',
+  );
+}

lib/src/video/x_video_player.dart

@@ -130,17 +130,26 @@ class XVideoPlayerValue {
 
 /// Owns one native video-player session. The surface mirrors the
 /// subset of `package:video_player`'s `VideoPlayerController` the app
-/// currently uses — only the `.file(...)` constructor, the standard
+/// currently uses — the `.file(...)` / `.network(...)` constructors, the
-/// playback controls, and the `value` getters compose / gallery /
+/// standard playback controls, and the `value` getters compose /
-/// outgoing-media read.
+/// gallery / outgoing-media read.
 ///
 /// Lifecycle: construct → [initialize] → use → [dispose]. After
 /// [dispose] every other method throws [XVideoPlayerException("disposed")].
 class XVideoPlayerController extends ChangeNotifier
     implements ValueListenable<XVideoPlayerValue> {
-  XVideoPlayerController.file(io.File file) : _file = file;
+  /// Play a local file.
+  XVideoPlayerController.file(io.File file) : _uri = 'file://${file.path}';
 
-  final io.File _file;
+  /// Stream from a network URL. The native side hands the URI straight
+  /// to Media3 (Android, `MediaItem.fromUri`) / `AVURLAsset` (Apple),
+  /// both of which stream http(s) natively — no extra setup.
+  XVideoPlayerController.network(Uri uri) : _uri = uri.toString();
+
+  /// Fully-qualified source URI handed to the native side at
+  /// [initialize]. `file://...` for [XVideoPlayerController.file], the
+  /// raw URL for [XVideoPlayerController.network].
+  final String _uri;
 
   XVideoPlayerValue _value = XVideoPlayerValue.uninitialized;
 
@@ -185,7 +194,7 @@ class XVideoPlayerController extends ChangeNotifier
   Future<void> _initInternal() async {
     try {
       final result = await XVideoPlayerBackend.instance.create(
-        uri: 'file://${_file.path}',
+        uri: _uri,
       );
       _handle = result.handle;
       _textureId = result.textureId;

lib/src/video/x_video_player_backend.dart

@@ -16,8 +16,9 @@ abstract class XVideoPlayerBackend {
   /// Swap to inject a fake before any UI code mounts a controller.
   static XVideoPlayerBackend instance = MethodChannelXVideoPlayerBackend();
 
-  /// Allocate a native player instance bound to [uri] (currently always
+  /// Allocate a native player instance bound to [uri] (`file://...` for
-  /// `file://...`). Returns the handle and, on Apple platforms, the
+  /// local playback, or an http(s) URL for network streaming). Returns
+  /// the handle and, on Apple platforms, the
   /// Flutter texture id; Android returns `textureId: null` because the
   /// render path is a platform view that takes the handle as creation
   /// params.

lib/ux.dart

@@ -14,6 +14,7 @@ export 'src/camera/camera.dart';
 export 'src/camera/camera_backend.dart' show XCameraBackend, XCameraCreateResult, XCameraEvent, XCameraDeviceOrientationChanged, XCameraSessionError, XCameraSessionInterrupted, XCameraSessionResumed, XCameraDiagnostic, XCameraPreviewSizeChanged;
 export 'src/camera/camera_channel.dart' show MethodChannelXCameraBackend;
 export 'src/camera/camera_preview.dart';
+export 'src/video/ffmpeg_license.dart' show registerFfmpegLicense;
 export 'src/video/x_video_player.dart';
 export 'src/video/x_video_player_backend.dart' show XVideoPlayerBackend, XVideoPlayerCreateResult, XVideoPlayerMetadata, XVideoPlayerEvent, XVideoPlayerStateChanged, XVideoPlayerSizeChanged, XVideoPlayerCompleted, XVideoPlayerError;
 export 'src/video/x_video_player_channel.dart' show MethodChannelXVideoPlayerBackend;

pubspec.lock

@@ -335,10 +335,10 @@ packages:
     dependency: "direct main"
     description:
       name: matcher
-      sha256: dc0b7dc7651697ea4ff3e69ef44b0407ea32c487a39fff6a4004fa585e901861
+      sha256: "12956d0ad8390bbcc63ca2e1469c0619946ccb52809807067a7020d57e647aa6"
       url: "https://pub.dev"
     source: hosted
-    version: "0.12.19"
+    version: "0.12.18"
   material_color_utilities:
     dependency: transitive
     description:
@@ -476,10 +476,10 @@ packages:
     dependency: transitive
     description:
       name: test_api
-      sha256: "8161c84903fd860b26bfdefb7963b3f0b68fee7adea0f59ef805ecca346f0c7a"
+      sha256: "93167629bfc610f71560ab9312acdda4959de4df6fac7492c89ff0d3886f6636"
       url: "https://pub.dev"
     source: hosted
-    version: "0.7.10"
+    version: "0.7.9"
   timing:
     dependency: transitive
     description:

pubspec.yaml

@@ -20,7 +20,7 @@ dependencies:
   flutter:
     sdk: flutter
   matcher: ^0.12.16
-  build: ^2.4.0
+  build: '>=2.4.0 <5.0.0'
   clock: ^1.1.1
   ffi: ^2.1.0
 
@@ -39,3 +39,7 @@ flutter:
         pluginClass: XPlugin
       macos:
         pluginClass: XPlugin
+  assets:
+    # LGPL-2.1 text for the bundled FFmpeg software H.264 decoder
+    # (libffmpegJNI.so, Android only). Surfaced via registerFfmpegLicense().
+    - assets/licenses/ffmpeg_LGPL-2.1.txt