このブログだとあまり明記していなかったので具体的なビルド手順を載せておこうかと。
必要な環境は、git, cmake, visual studio 2022ぐらいかな？現時点では全て誰でもダウンロード可能です。
ビルドに必要な空き容量NTFSで 6.26GB となっていました。
PowerShell 7.5.2
PS C:\Users\xxxxx> mkdir S:\obs\31.1.1\
Directory: S:\obs
Mode LastWriteTime Length Name
---- ------------- ------ ----
d---- 25/07/15 09:12 31.1.1
PS C:\Users\xxxxx> s:
PS S:\> cd \obs\31.1.1
PS S:\obs\31.1.1> git clone --recursive https://github.com/obsproject/obs-studio.git -b 31.1.1 --depth 1
Cloning into 'obs-studio'...
remote: Enumerating objects: 5326, done.
remote: Counting objects: 100% (5326/5326), done.
remote: Compressing objects: 100% (4434/4434), done.
remote: Total 5326 (delta 879), reused 3056 (delta 657), pack-reused 0 (from 0)
Receiving objects: 100% (5326/5326), 14.86 MiB | 14.24 MiB/s, done.
Resolving deltas: 100% (879/879), done.
warning: refs/tags/31.1.1 4b56b9b214967c6f0143e36f722c64c6d755d55f is not a commit!
Note: switching to 'a32b3f9f6d5e1cf6fa0f8105a2ed46ec0b4d991c'.
You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.
If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:
git switch -c <new-branch-name>
Or undo this operation with:
git switch -
Turn off this advice by setting config variable advice.detachedHead to false
Updating files: 100% (5043/5043), done.
Submodule 'plugins/win-dshow/libdshowcapture' (https://github.com/obsproject/libdshowcapture.git) registered for path 'deps/libdshowcapture/src'
Submodule 'plugins/obs-browser' (https://github.com/obsproject/obs-browser.git) registered for path 'plugins/obs-browser'
Submodule 'plugins/obs-websocket' (https://github.com/obsproject/obs-websocket.git) registered for path 'plugins/obs-websocket'
Cloning into 'S:/obs/31.1.1/obs-studio/deps/libdshowcapture/src'...
remote: Enumerating objects: 1037, done.
remote: Counting objects: 100% (604/604), done.
remote: Compressing objects: 100% (96/96), done.
remote: Total 1037 (delta 537), reused 511 (delta 508), pack-reused 433 (from 2)
Receiving objects: 100% (1037/1037), 332.23 KiB | 10.07 MiB/s, done.
Resolving deltas: 100% (722/722), done.
Cloning into 'S:/obs/31.1.1/obs-studio/plugins/obs-browser'...
remote: Enumerating objects: 3799, done.
remote: Counting objects: 100% (1676/1676), done.
remote: Compressing objects: 100% (444/444), done.
remote: Total 3799 (delta 1376), reused 1258 (delta 1232), pack-reused 2123 (from 2)
Receiving objects: 100% (3799/3799), 1.09 MiB | 10.11 MiB/s, done.
Resolving deltas: 100% (2594/2594), done.
Cloning into 'S:/obs/31.1.1/obs-studio/plugins/obs-websocket'...
remote: Enumerating objects: 6189, done.
remote: Counting objects: 100% (823/823), done.
remote: Compressing objects: 100% (203/203), done.
remote: Total 6189 (delta 656), reused 631 (delta 618), pack-reused 5366 (from 4)
Receiving objects: 100% (6189/6189), 1.75 MiB | 10.62 MiB/s, done.
Resolving deltas: 100% (4258/4258), done.
Submodule path 'deps/libdshowcapture/src': checked out '8878638324393815512f802640b0d5ce940161f1'
Submodule 'external/capture-device-support' (https://github.com/elgatosf/capture-device-support) registered for path 'deps/libdshowcapture/src/external/capture-device-support'
Cloning into 'S:/obs/31.1.1/obs-studio/deps/libdshowcapture/src/external/capture-device-support'...
remote: Enumerating objects: 60, done.
remote: Counting objects: 100% (60/60), done.
remote: Compressing objects: 100% (41/41), done.
remote: Total 60 (delta 30), reused 41 (delta 19), pack-reused 0 (from 0)
Receiving objects: 100% (60/60), 34.39 KiB | 5.73 MiB/s, done.
Resolving deltas: 100% (30/30), done.
Submodule path 'deps/libdshowcapture/src/external/capture-device-support': checked out 'fe9630974d47f51bf54826e72fb8b654e620aa93'
Submodule path 'plugins/obs-browser': checked out 'bdabf8300ecefeb566b81f4a7ff75f8a8e21f62b'
Submodule path 'plugins/obs-websocket': checked out '40d26dbf4d29137bf88cd393a3031adb04d68bba'
PS S:\obs\31.1.1> cmake-gui
PS S:\obs\31.1.1>
cmake-guiが起動した後は、上の方から設定します。
Configureを押し、ビルドするフォルダの作成の確認をした後、終了するまでしばらく待ちます。完了したらGenerateを押し、またしばらく待ちます。終わったらOpen Projectを押すとVisual Studio2022が起動します。
実際にビルドするには必要かどうかわかりませんが、ソリューションの構成をReleaseにしてデバッグなしで開始(Ctrl+F5)を押すと実行ファイルの作成が始まります。この状態で放置して、しばらくすると（手元のネットブックだと35分ほど）obs-studioが実行された状態になります。
一回ビルドを通しておけば、ソースの修正などを行う時に型チェックなどがまともになるので時間があるのであれば一度ビルドしておくことをお勧めします。
失敗するパターンとしてはファイルシステムがWindowsではNTFSでないとcmakeでエラーが出て進まなくなりました。
