[feature] more filetype support! (#3107)

* add more supported file types to our media processor that ffmpeg supports, update supported mime type lists

* add code comments to the supported mime types slice

* don't check for zero value string, just parse

* remove some unneeded consts which make the code a bit harder to read

* fix test expected instance media mime types, use compact ffprobe json, simple media processing by type

* final tweaks to media processing code

* don't use safe divide where we don't need to

2 files changed, 43 insertions, 0 deletions

diff --git a/internal/util/math.go b/internal/util/math.go
new file mode 100644
index 000000000..e1850f772
--- /dev/null
+++ b/internal/util/math.go
@@ -0,0 +1,34 @@
+// 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/>.
+
+package util
+
+type Number interface {
+	~int | ~int8 | ~int16 | ~int32 | ~int64 |
+		~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 |
+		~uintptr | ~float32 | ~float64
+}
+
+// Div performs a safe division of
+// n1 and n2, checking for zero n2. In the
+// case of zero n2, zero is returned.
+func Div[N Number](n1, n2 N) N {
+	if n2 == 0 {
+		return 0
+	}
+	return n1 / n2
+}
diff --git a/internal/util/ptr.go b/internal/util/ptr.go
index 0ad207617..d7c30da85 100644
--- a/internal/util/ptr.go
+++ b/internal/util/ptr.go
@@ -34,6 +34,15 @@ func Ptr[T any](t T) *T {
 	return &t
 }
 
+// PtrIf returns ptr value only if 't' non-zero.
+func PtrIf[T comparable](t T) *T {
+	var z T
+	if t == z {
+		return nil
+	}
+	return &t
+}
+
 // PtrValueOr returns either value of ptr, or default.
 func PtrValueOr[T any](t *T, _default T) T {
 	if t != nil {