Read CRI USM game videos (.usm) (#485)

docs/ENGINES.md

@@ -1407,6 +1407,9 @@ streams without a container: FFmpeg reports them as format `hevc` / `h264` (`Med
 encoded, never copied, because their frames carry no timestamps (a copy into MP4 had non-monotonic DTS). A stream
 without timing information is read at FFmpeg's default 25 fps, so a camera that recorded at another rate plays faster
 or slower; its frames are all kept.
+CRI USM (`.usm`, read only, #485), the video of many games' cutscenes, is read by FFmpeg's `usm` demuxer and goes to
+every video and audio target like the other read-only containers. Encrypted USM files (common in recent games) can't
+be read and fail with FFmpeg's error.
 A Video CD's `MPEGAV/AVSEQ01.DAT` (MPEG-1 in a RIFF/CDXA wrapper) counts as MPEG: `.dat` is an extension of that
 format, and FFmpeg reads what the file holds, so a `.dat` with no video in it fails instead of making a file.
 

src/Filee.Core/Formats/FormatRegistry.cs

@@ -224,6 +224,8 @@ public static class FormatRegistry
         new("swf", "SWF", FormatCategory.Video, ["swf"], Writable: false),
         new("wtv", "WTV", FormatCategory.Video, ["wtv", "dvr-ms", "dvr"], Writable: false),
         new("cavs", "CAVS", FormatCategory.Video, ["cavs"], Writable: false),
+        // CRI Middleware's video for game cutscenes (#485): FFmpeg's usm demuxer reads unencrypted ones.
+        new("usm", "USM", FormatCategory.Video, ["usm"], Writable: false),
         // Raw H.265 / H.264 streams with no container, as security cameras and VMS software export them (issue #301).
         new("h265", "H.265", FormatCategory.Video, ["h265", "265", "hevc"], Writable: false),
         new("h264", "H.264", FormatCategory.Video, ["h264", "264"], Writable: false),

src/Filee.Core/Settings/AppSettings.cs

@@ -123,7 +123,7 @@ public static bool IsFlipKeyAllowed(string key, IEnumerable<TriggerGesture> gest
 public sealed class AppSettings
 {
     /// <summary>Current schema version. Increase when the format changes and add a migration.</summary>
-    public const int CurrentSchemaVersion = 43;
+    public const int CurrentSchemaVersion = 44;
 
     public int SchemaVersion { get; set; } = CurrentSchemaVersion;
 

src/Filee.Core/Settings/UserDataStore.cs

@@ -840,6 +840,9 @@ public static bool ApplyToLibrary(int from, List<Preset> presets, List<ToolbarPr
         //      renumbered if another change takes it first.)
         if (from < 43)
             changed |= LearnExtensions(profiles, out _, ["fits", "fts"]);
+        // v44: CRI USM game videos (.usm) learn the video donut; custom claims stay put.
+        if (from < 44)
+            changed |= LearnExtensions(profiles, out _, ["usm"]);
         return changed;
     }
 

tests/Filee.Core.Tests/UsmFormatTests.cs

@@ -0,0 +1,34 @@
+// CRI USM game videos (#485): a read-only video source on the video donut, learned by existing libraries.
+
+using Filee.Core.Formats;
+using Filee.Core.Presets;
+using Filee.Core.Profiles;
+using Filee.Core.Settings;
+
+namespace Filee.Core.Tests;
+
+public class UsmFormatTests
+{
+    [Fact]
+    public void Usm_is_a_video_filee_reads_but_never_writes()
+    {
+        var usm = FormatRegistry.Detect("cutscene.USM");
+        Assert.NotNull(usm);
+        Assert.Equal(("usm", FormatCategory.Video, false), (usm.Id, usm.Category, usm.Writable));
+        Assert.Equal("video", ProfileSelector.Select(BuiltInData.CreateProfiles(), ["movie01.usm"])?.Id);
+    }
+
+    [Fact]
+    public void Version_43_libraries_learn_usm_once()
+    {
+        var presets = BuiltInData.CreatePresets();
+        var profiles = BuiltInData.CreateProfiles();
+        var video = profiles.Single(p => p.Id == "video");
+        video.Extensions.Remove("usm");
+
+        Assert.True(SettingsMigrations.ApplyToLibrary(43, presets, profiles));
+
+        Assert.Contains("usm", video.Extensions);
+        Assert.False(SettingsMigrations.ApplyToLibrary(43, presets, profiles));
+    }
+}

tests/Filee.Engines.Tests/MediaTests.cs

@@ -23,6 +23,17 @@
 [Collection(nameof(FfmpegCollection))]
 public class MediaTests(EngineFixture fx) : IClassFixture<EngineFixture>
 {
+    [Fact]
+    public void Cri_usm_game_videos_go_to_mp4_through_ffmpeg()
+    {
+        // #485: read only, through FFmpeg's usm demuxer; never a step towards something else.
+        SkipUnlessInstalled();
+        var route = fx.Catalog.CreatePlanner().Plan("usm", "mp4");
+        Assert.NotNull(route);
+        Assert.Equal("ffmpeg", Assert.Single(route.Steps).Converter.Id);
+        Assert.Null(fx.Catalog.CreatePlanner().Plan("mp4", "usm"));
+    }
+
     private static readonly (string Ffmpeg, string Ffprobe)? Tools = FfmpegConverter.Locate();
 
     private static void SkipUnlessInstalled() =>
@@ -754,7 +765,7 @@
         // The coded pictures are the source's, byte for byte.
         async Task<string> Hash(string file)
         {
             var hash = await ProcessRunner.RunAsync(Tools.Value.Ffmpeg,
                 ["-hide_banner", "-v", "error", "-i", file, "-map", "0:v", "-c", "copy", "-f", "hash", "-hash", "md5", "-"],
                 TimeSpan.FromMinutes(1), CancellationToken.None);
             return hash.StandardOutput.Trim();