[feature] support processing of (many) more media types (#3090)

* initial work replacing our media decoding / encoding pipeline with ffprobe + ffmpeg

* specify the video codec to use when generating static image from emoji

* update go-storage library (fixes incompatibility after updating go-iotools)

* maintain image aspect ratio when generating a thumbnail for it

* update readme to show go-ffmpreg

* fix a bunch of media tests, move filesize checking to callers of media manager for more flexibility

* remove extra debug from error message

* fix up incorrect function signatures

* update PutFile to just use regular file copy, as changes are file is on separate partition

* fix remaining tests, remove some unneeded tests now we're working with ffmpeg/ffprobe

* update more tests, add more code comments

* add utilities to generate processed emoji / media outputs

* fix remaining tests

* add test for opus media file, add license header to utility cmds

* limit the number of concurrently available ffmpeg / ffprobe instances

* reduce number of instances

* further reduce number of instances

* fix envparsing test with configuration variables

* update docs and configuration with new media-{local,remote}-max-size variables

vendor/codeberg.org/gruf/go-ffmpreg/ffprobe/ffprobe.go

@@ -0,0 +1,108 @@
+package ffprobe
+
+import (
+	"context"
+
+	"codeberg.org/gruf/go-ffmpreg/embed/ffprobe"
+	"codeberg.org/gruf/go-ffmpreg/internal"
+	"codeberg.org/gruf/go-ffmpreg/util"
+	"codeberg.org/gruf/go-ffmpreg/wasm"
+	"github.com/tetratelabs/wazero"
+	"github.com/tetratelabs/wazero/api"
+	"github.com/tetratelabs/wazero/imports/wasi_snapshot_preview1"
+)
+
+// pool of WASM module instances.
+var pool = wasm.InstancePool{
+	Instantiator: wasm.Instantiator{
+
+		// WASM module name.
+		Module: "ffprobe",
+
+		// Per-instance WebAssembly runtime (with shared cache).
+		Runtime: func(ctx context.Context) wazero.Runtime {
+
+			// Prepare config with cache.
+			cfg := wazero.NewRuntimeConfig()
+			cfg = cfg.WithCoreFeatures(ffprobe.CoreFeatures)
+			cfg = cfg.WithCompilationCache(internal.Cache)
+
+			// Instantiate runtime with our config.
+			rt := wazero.NewRuntimeWithConfig(ctx, cfg)
+
+			// Prepare default "env" host module.
+			env := rt.NewHostModuleBuilder("env")
+			env = env.NewFunctionBuilder().
+				WithGoModuleFunction(
+					api.GoModuleFunc(util.Wasm_Tempnam),
+					[]api.ValueType{api.ValueTypeI32, api.ValueTypeI32},
+					[]api.ValueType{api.ValueTypeI32},
+				).
+				Export("tempnam")
+
+			// Instantiate "env" module in our runtime.
+			_, err := env.Instantiate(context.Background())
+			if err != nil {
+				panic(err)
+			}
+
+			// Instantiate the wasi snapshot preview 1 in runtime.
+			_, err = wasi_snapshot_preview1.Instantiate(ctx, rt)
+			if err != nil {
+				panic(err)
+			}
+
+			return rt
+		},
+
+		// Per-run module configuration.
+		Config: wazero.NewModuleConfig,
+
+		// Embedded WASM.
+		Source: ffprobe.B,
+	},
+}
+
+// Precompile ensures at least compiled ffprobe
+// instance is available in the global pool.
+func Precompile(ctx context.Context) error {
+	inst, err := pool.Get(ctx)
+	if err != nil {
+		return err
+	}
+	pool.Put(inst)
+	return nil
+}
+
+// Get fetches new ffprobe instance from pool, prefering cached if available.
+func Get(ctx context.Context) (*wasm.Instance, error) { return pool.Get(ctx) }
+
+// Put places the given ffprobe instance in pool.
+func Put(inst *wasm.Instance) { pool.Put(inst) }
+
+// Run will run the given args against an ffprobe instance from pool.
+func Run(ctx context.Context, args wasm.Args) (uint32, error) {
+	inst, err := pool.Get(ctx)
+	if err != nil {
+		return 0, err
+	}
+	rc, err := inst.Run(ctx, args)
+	pool.Put(inst)
+	return rc, err
+}
+
+// Cached returns a cached instance (if any) from pool.
+func Cached() *wasm.Instance { return pool.Cached() }
+
+// Free drops all instances
+// cached in instance pool.
+func Free() {
+	ctx := context.Background()
+	for {
+		inst := pool.Cached()
+		if inst == nil {
+			return
+		}
+		_ = inst.Close(ctx)
+	}
+}