[feature/OFFICIALLY UNSUPPORTED] add nowasm build tag to disable building with WebAssembly (#3429)

* add experimental build-tag 'nowasm' which uses local ffmpeg / ffprobe

* updated experimental support message

* add comment to build script explaining build tag

* add nowasm build tags to moderncsqlite files

1 files changed, 49 insertions, 0 deletions

diff --git a/internal/media/ffmpeg/ffmpeg_nowasm.go b/internal/media/ffmpeg/ffmpeg_nowasm.go
new file mode 100644
index 000000000..6f528da1a
--- /dev/null
+++ b/internal/media/ffmpeg/ffmpeg_nowasm.go
@@ -0,0 +1,49 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+//go:build nowasm
+
+package ffmpeg
+
+import (
+	"context"
+	"os/exec"
+)
+
+// ffmpegRunner limits the number of
+// ffmpeg WebAssembly instances that
+// may be concurrently running, in
+// order to reduce memory usage.
+var ffmpegRunner runner
+
+// InitFfmpeg looks for a local copy of ffmpeg in path, and prepares
+// the runner to only allow max given concurrent running instances.
+func InitFfmpeg(ctx context.Context, max int) error {
+	_, err := exec.LookPath("ffmpeg")
+	if err != nil {
+		return err
+	}
+	ffmpegRunner.Init(max)
+	return nil
+}
+
+// Ffmpeg runs the given arguments with an instance of ffmpeg.
+func Ffmpeg(ctx context.Context, args Args) (uint32, error) {
+	return ffmpegRunner.Run(ctx, func() (uint32, error) {
+		return runCmd(ctx, "ffmpeg", args)
+	})
+}