meson: Add and enable dav1d for AV1 decoding

.gitignore

@@ -6,6 +6,7 @@ build*/
 subprojects/boost*/
 subprojects/cairo*
 subprojects/curl-*
+subprojects/dav1d
 subprojects/ffmpeg
 subprojects/ffms2*
 subprojects/fontconfig*

meson.build

@@ -1,7 +1,7 @@
 project('Aegisub', ['c', 'cpp'],
         license: 'BSD-3-Clause',
         meson_version: '>=0.57.0',
-        default_options: ['cpp_std=c++20', 'buildtype=debugoptimized', 'harfbuzz:icu=disabled'],
+        default_options: ['cpp_std=c++20', 'buildtype=debugoptimized', 'harfbuzz:icu=disabled', 'ffmpeg:libdav1d=enabled'],
         version: '3.4.0')
 
 cmake = import('cmake')

src/dialog_about.cpp

@@ -104,6 +104,7 @@ void ShowAboutDialog(wxWindow *parent) {
 #ifdef WITH_FFMS2
 		"    FFmpeg - Copyright (c) Fabrice Bellard;\n"
 		"    FFMS2 - Copyright (c) Fredrik Mellbin;\n"
+		"    dav1d - Copyright (c) VideoLAN and dav1d authors;\n"
 #endif
 #ifdef WITH_AVISYNTH
 		"    Avisynth 2.5 - Copyright (c) Ben Rudiak-Gould et al;\n"

subprojects/dav1d.wrap

@@ -0,0 +1,7 @@
+[wrap-git]
+directory = dav1d
+url = https://github.com/videolan/dav1d.git
+revision = head
+
+[provide]
+dav1d = dav1d_dep