Support reading metadata without loading entire moov

Mbucari · Aug 27, 2023 · ac826f9 · ac826f9
1 parent 3e4c479
commit ac826f9
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Showing 3 changed files with 53 additions and 9 deletions.
diff --git a/src/AAXClean/AAXClean.csproj b/src/AAXClean/AAXClean.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>net6.0</TargetFramework>
-    <Version>1.1.0</Version>
+    <Version>1.1.1</Version>
     <Authors>MrGneissGuy</Authors>
     <Company>Just Me, Inc.</Company>
     <Description>Decrypts Audible aax and aaxc files to mp4.</Description>
@@ -26,10 +26,16 @@
 	  <PublishReadyToRun>true</PublishReadyToRun>
 	  <DebugType>embedded</DebugType>
   </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
 
   <ItemGroup>
     <ProjectReference Include="..\Mpeg4Lib\Mpeg4Lib.csproj" />
-  	<PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1" PrivateAssets="All" />
   </ItemGroup>
 
 </Project>
diff --git a/src/AAXClean/AppleTags.cs b/src/AAXClean/AppleTags.cs
@@ -1,5 +1,7 @@
 using Mpeg4Lib.Boxes;
+using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 
 namespace AAXClean
@@ -40,12 +42,13 @@ public AppleTags(AppleListBox appleListBox)
 		public string Version { get => IList.GetTagString("VERS"); set => IList.EditOrAddTag("VERS", value); }
 		public byte[] Cover { get => IList.GetTagBytes("covr"); set => IList.EditOrAddTag("covr", value, AppleDataType.JPEG); }
 
-		public (int trackNum, int trackCount) Tracks
+		[DisallowNull]
+		public (int trackNum, int trackCount)? Tracks
 		{
 			get
 			{
 				var data = IList.GetTagBytes("trkn");
-				if (data is null) return (1, 1);
+				if (data is null) return null;
 
 				int trackNum = (data[2] << 8) | data[3];
 				int trackCount = (data[4] << 8) | data[5];
@@ -54,16 +57,44 @@ public AppleTags(AppleListBox appleListBox)
 			}
 			set
 			{
+				if (value is not (int trackNum, int trackCount))
+					throw new ArgumentNullException(nameof(Tracks), "Cannot set to null");
+
 				var data = new byte[8];
 
-				data[3] = (byte)value.trackNum;
-				data[2] = (byte)(value.trackNum >> 8);
+				data[3] = (byte)trackNum;
+				data[2] = (byte)(trackNum >> 8);
 
-				data[5] = (byte)value.trackCount;
-				data[4] = (byte)(value.trackCount >> 8);
+				data[5] = (byte)trackCount;
+				data[4] = (byte)(trackCount >> 8);
 
 				IList.EditOrAddTag("trkn", data);
 			}
 		}
+
+		public static AppleTags FromFile(string mp4File)
+		{
+			using var file = System.IO.File.Open(mp4File, System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.Read);
+
+			BoxHeader header;
+			do
+			{
+				header = new BoxHeader(file);
+
+				if (header.Type is "moov")
+					continue;
+				else if (header.Type is "udta")
+					break;
+				else
+					file.Position += header.TotalBoxSize - header.HeaderSize;
+
+			}while(file.Position < file.Length);
+
+			if (header?.Type is not "udta") return null;
+
+			var ilst = new UdtaBox(file, header, null)?.GetChild<MetaBox>()?.GetChild<AppleListBox>();
+
+			return ilst is null ? null : new AppleTags(ilst);
+		}
 	}
 }
diff --git a/src/Mpeg4Lib/Mpeg4Lib.csproj b/src/Mpeg4Lib/Mpeg4Lib.csproj
@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>net6.0</TargetFramework>
-	  <Version>0.1.2</Version>
+	  <Version>0.1.20</Version>
 	  <Authors>MrGneissGuy</Authors>
 	  <Company>Just Me, Inc.</Company>
 	  <Description>Parsees mpeg-4 files</Description>
@@ -22,4 +22,11 @@
 		<DebugType>embedded</DebugType>
 	</PropertyGroup>
 
+	<ItemGroup>
+	  <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1">
+	    <PrivateAssets>all</PrivateAssets>
+	    <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+	  </PackageReference>
+	</ItemGroup>
+
 </Project>