[sbokatuk]

Moves FFmpegKit from 8.1.7 to 8.1.9, which is the first release on FFmpeg n8.1.3, and fixes an app freeze that also affects the published 8.1.2.5. Package 8.1.3.1, tag v8.1.3.1.

Closes #21

Don't merge until you've approved it: merging docs/release-notes/8.1.3.1.md is the release.

Please review first

1. A freeze fix that isn't part of the version bump (commit 73232f5). G4 could not pass without it. The example app froze with an ANR on its first conversion, and it does the same on the published 8.1.2.5, so this is not a regression from 8.1.9.

• Cause: Mono on Android restarts threads after a garbage collection with SIGXCPU, and FFmpeg's term_init installs its own handler for that signal. The next collection after an FFmpeg command then leaves every managed thread suspended for good.
• Why nothing caught it: CI never deploys the sample, and the device checks allocated too little to trigger a collection.
• Fix: FFmpegKitConfig.IgnoreSignal(Signal.Sigxcpu) from static constructors on FFmpegKit, FFmpegKitConfig and AsyncFFmpegExecuteTask. No public API changes. A module initializer was rejected because it would load the native libraries with the assembly, which breaks apps that gate FFmpegKit at runtime.
• Proof: with the one-line opt-out added to the sample, conversions complete. The new device check forces collections after FFmpeg has run. It hangs on 8.1.2.5 and on unfixed 8.1.3.1, and passes in all 10 G3 runs here.

2. Two device check fixes (commit b49d886). Running all eight variants exposed them, because CI's emulator job only runs Video:

• ExternalLibraries had to be non-empty, but min has none. The published 8.1.2.5 fails the same way.
• The progress check stopped waiting at the first sample, which is at position zero, and could then fail with "Position never advanced". It now waits for a sample that advanced, so it is just as strict.

The progress race failed 2 of 9 cold starts on 8.1.3.1 and 0 of 24 on 8.1.2.5, so I can't show that it predates this bump. After the fix, 60 of 60 cold starts pass, each receiving both samples, so no callback is being lost.

What changed upstream

• FFmpeg n8.1.2 → n8.1.3, read from libavcodec.so in all 8 variants on both ABIs. Upstream reports that this closes CVE-2026-64830 and CVE-2026-64835. FFmpeg's own history has the matching VobSub and ADX fixes; the CVE numbers are upstream's claim.
• drawtext returns to Full, FullGpl and Video: --enable-libharfbuzz and the filter are in the shipped libraries. This was checked in the binaries, not by running the filter on a device.
• Upstream reports that a -filter_complex parse error no longer kills the process. Not verified here.
• Min and Https now ship libc++_shared.so, about 1 MB larger .aar.
• The 8.1.9 .pom now declares smart-exception. The jars stay embedded, because no .NET build reads a .pom.

Everything outside jni/ is identical to 8.1.7 in all 8 variants, licences included. All 160 .so files pass a static GNU_RELRO check and are 16 KB aligned.

API changes: none. classes.jar is byte-identical to 8.1.7 in all 8 variants, and generated api.xml matches in all 24 variant and framework pairs, so Metadata.xml is unchanged. Target frameworks, ABIs, minSdk 24 and licensing are unchanged.

Mapping: added 8.1.3 8.1.9 and kept 8.1.2 8.1.7, so 8.1.7 stays rebuildable. The brief's replace-the-row step and its "8.1.7 can no longer be rebuilt" line don't apply, because this is a new FFmpeg.

Test report — FFmpegKit.Net.*.Android 8.1.3.1-local.20261030121512

Toolchain: .NET SDK 8.0.427 / 9.0.320 / 10.0.403, android workloads 34.0.154 / 35.0.105 / 36.1.118, JDK 17.0.21, emulator ffmpegkit_e2e (API 35 google_apis, arm64-v8a), physical Pixel 10 (Android 17, API 37, arm64-v8a). No Xcode involved.

Gate	Target	TFM	Result	Evidence
G1 pack	all 8 variants, both bands	net8, net9, net10	PASS	8 nupkgs, 8 snupkgs; correct .aar, licence and n8.1.3 on both ABIs in each
G2 package tests	all 8 variants		PASS	190/190; suite also shown to fail on an empty folder and on a relabelled licence
G3 Audio	emulator	net10.0-android36.0	PASS	15/15, ffmpeg=n8.1.3, package=audio
G3 Full	emulator	net10.0-android36.0	PASS	15/15, ffmpeg=n8.1.3, package=custom (see note)
G3 FullGpl	emulator	net10.0-android36.0	PASS	15/15, ffmpeg=n8.1.3, package=custom (see note)
G3 Https	emulator	net10.0-android36.0	PASS	15/15, ffmpeg=n8.1.3, package=https
G3 HttpsGpl	emulator	net10.0-android36.0	PASS	15/15, ffmpeg=n8.1.3, package=https-gpl
G3 Min	emulator	net10.0-android36.0	PASS	15/15, ffmpeg=n8.1.3, package=min
G3 MinGpl	emulator	net10.0-android36.0	PASS	15/15, ffmpeg=n8.1.3, package=min-gpl
G3 Video	emulator	net10.0-android36.0	PASS	15/15, ffmpeg=n8.1.3, package=video
G3 Full	emulator	net8.0-android34.0	PASS	15/15, ffmpeg=n8.1.3
G3 Video	emulator	net8.0-android34.0	PASS	15/15, ffmpeg=n8.1.3
G4 Example	emulator	net10.0-android36.0	PASS	"Source: 320x240, 3s, mpeg4."; Resize 107,659, Grayscale 99,770, AAC 27,731 bytes; all three played
G4 Example	emulator	net9.0-android35.0	PASS	same results
G4 Example	emulator	net8.0-android34.0	PASS	same results; not required by the brief, added because CI builds this band
G3 all 8 variants	Pixel 10, Android 17 (API 37)	net10.0-android36.0	PASS	15/15 each, ffmpeg=n8.1.3, GC check passed; not required, added on the maintainer's request
G3 Full, Video	Pixel 10, Android 17 (API 37)	net8.0-android34.0	PASS	15/15 each, ffmpeg=n8.1.3
G4 Example	Pixel 10, Android 17 (API 37)	net10, net9 and net8	PASS	probe correct; Resize 109,957, Grayscale 102,323, AAC 27,731 bytes; all three played on every band
G5 umbrella samples			N/A	belongs to F2, after this is published
G6 PR CI	ubuntu, emulator API 35 x86_64, Video	net8.0-android34.0, net10.0-android36.0	PASS	all 7 checks green on d218ca7; both emulator legs FFMPEGKIT_E2E_DONE PASS passed=15, ffmpeg=n8.1.3, GC check passed
G7 consumer path			N/A	packaging and .targets are unchanged

No check is SKIPPED.

Notes on the evidence:

• Commits: G3 ran on the final test code (d218ca7). The package, G1, G2 and G4 are from before that commit, which only changes SmokeTests.cs, a file that isn't packed.
• Version check: SmokeTests only asserts that FFmpegVersion is non-empty, so the local G3 runner compared the logged value against n8.1.3 itself. It's still not enforced in CI.
• package=custom: published 8.1.2.5 Full reports the same, with an identical library list, so it isn't a change.
• Playback: paused frames of the After player were identical and frames during playback differed. Position advanced, and the resize clip's on-screen counter moved. The AAC result has no video track, so its picture is black by design and only the position moves.
• Progress in the sample: the in-progress state was seen ("Starting…", bar, "Converting…", Cancel enabled), but no percentage was caught, because these conversions finish in under a second. Numeric progress is covered by G3's reports progress check.
• x86_64: runs on a device only through this PR's CI, on the Video variant. Locally everything ran on arm64.
• Android levels: API 35 (emulator) and API 37 (Pixel 10, 4 KB pages). Nothing below API 35 was run, and no device with 16 KB pages was available.
• Output sizes: video files differ between the Pixel and the emulator, which have 8 and 2 cores. Each file has the expected 75 frames and resolution, and the AAC output is identical. The likely cause is the encoder's thread count, which I didn't test separately.
• 16 KB warning on net8: Android 17 shows a compatibility dialog on the debuggable net8 sample. All 10 FFmpegKit libraries are 16 KB aligned in the net8, net9 and net10 APKs. The unaligned ones in net8 belong to .NET 8 itself (libmonosgen, libmonodroid, libSystem.*), and net9 and net10 have none. This isn't new and this binding can't fix it. net8 apps will depend on that .NET 8 runtime on 16 KB devices.

Corrections to the brief and setup

• The SDK 8 and 9 manifests on the build Mac want net8 mono packs at 8.0.33, but 8.0.23 is installed in the root-owned /usr/local/share/dotnet. That breaks every net8 Android build there, including clean origin/main. For this run the eight verified Microsoft packs came from a private DOTNETSDK_WORKLOAD_PACK_ROOTS folder, with no machine or repo change. The real fix needs sudo, probably dotnet workload repair, which I haven't tested.
• -t:Install on the sample needs -f <tfm>, because it uses plural TargetFrameworks. The README is corrected.
• docs/release-notes/README.md doesn't exist, so the house style came from the existing notes.
• Issue Upstream drift: FFmpegKit #21's text still says 8.1.8; the checker now reports 8.1.9.
• CI's emulator job only runs Video, and the sample is never deployed there, which is how the freeze stayed hidden. Worth a separate change.

🤖 Generated with Claude Code

[Copilot]

🟡 Changes recommended

The regression test can pass without exercising the second managed thread’s stop/restart because garbage collection and shutdown may complete before the allocator task starts.

1 open issue

• Wait for allocator startup before testing thread stop/restart · New

What changed in this PR

Updates the Android bindings to FFmpegKit 8.1.9 (FFmpeg n8.1.3) for package 8.1.3.1 and adds protection against the Mono garbage-collection freeze caused by FFmpeg taking over SIGXCPU.

Changes:

• Adds the native version mapping and checksum baseline while preserving older mappings.
• Introduces lazy signal protection, a garbage-collection regression check, and corrections to progress and Min-variant checks.
• Updates release notes, version examples, and dependency documentation without changing the public API.

File	Description
tests/​FFmpegKit.Android.PackageTests/​PackageLayoutTests.cs	Updates comments about native filenames and runtime dependencies.
tests/​FFmpegKit.Android.DeviceTests/​SmokeTests.cs	Adds the freeze regression check and adjusts progress and library assertions.
src/​FFmpegKit.Android/​Jars/​FetchJars.sh	Clarifies smart-exception dependency comments.
src/​FFmpegKit.Android/​FFmpegKit.Android.csproj	Updates comments explaining embedded jars.
src/​FFmpegKit.Android/​BuildNugets.sh	Revises usage examples and documents local version naming.
src/​FFmpegKit.Android/​Additions/​FFmpegKit.Signals.cs	Adds static initialisation to protect Mono's restart signal.
samples/​FFmpegKit.Android.Example/​FFmpegKit.Android.Example.csproj	Updates version examples and explanatory comments.
README.md	Documents the upgrade, freeze protection, and corrected build instructions.
docs/​release-notes/​8.1.3.1.md	Records fixes, native changes, and validation results.
Directory.Build.props	Sets FFmpeg 8.1.3 and FFmpegKit 8.1.9 defaults.
build/​native-versions.tsv	Appends the new version pairing.
build/​checksums/​8.1.9.sha256	Adds checksums for eight native archives and two jars.
.github/​copilot-instructions.md	Updates version guidance and signal-protection requirements.

_{Review effort: Balanced}