'Fat' signature density research

AlekseyMartynov · Sep 12, 2023 · b9ad17c · b9ad17c
1 parent 172024d
commit b9ad17c
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Showing 3 changed files with 48 additions and 13 deletions.
diff --git a/Tagging/Sig.cs b/Tagging/Sig.cs
@@ -136,25 +136,45 @@ public static void Read(byte[] data, out int sampleRate, out int sampleCount, ou
             writableBands[i] = new();
 
         while(mem.Position < mem.Length) {
-            var bandIndex = reader.ReadInt32() - 0x60030040;
-            if(bandIndex < 0 || bandIndex > 3)
-                throw new InvalidOperationException();
+            var fat = false;
+            var bandIndex = 0;
+            var header = reader.ReadInt32();
+
+            if(header == 0x60023e80) {
+                fat = true;
+            } else {
+                bandIndex = header - 0x60030040;
+                if(bandIndex < 0 || bandIndex > 3)
+                    throw new InvalidOperationException();
+            }
 
             var len = reader.ReadInt32();
             var end = mem.Position + len;
             var stripe = 0;
 
             while(mem.Position < end) {
                 if(end - mem.Position >= 5) {
-                    var x = reader.ReadByte();
-                    if(x == 255) {
+                    if(fat) {
                         stripe = reader.ReadInt32();
-                        x = reader.ReadByte();
+                    } else {
+                        var x = reader.ReadByte();
+                        if(x == 255) {
+                            stripe = reader.ReadInt32();
+                            x = reader.ReadByte();
+                        }
+                        stripe += x;
+                    }
+
+                    var word1 = reader.ReadUInt16();
+                    var word2 = reader.ReadUInt16();
+
+                    if(fat) {
+                        mem.Position += 4;
+                        (word1, word2) = (word2, word1);
                     }
-                    stripe += x;
 
-                    var magn = reader.ReadUInt16();
-                    var bin = reader.ReadUInt16() / 64;
+                    var magn = word1;
+                    var bin = word2 / 64;
 
                     if(bin == 0 || magn == 0)
                         throw new InvalidOperationException();
@@ -228,6 +248,7 @@ static int GetSampleRateCode(int sampleRate) {
     }
 
     static int SampleRateFromCode(int code) {
+        code &= 0xf;
         return code switch {
             1 => 8000,
             3 => 16000,

diff --git a/Test/PeakDensityResearch.cs b/Test/PeakDensityResearch.cs
@@ -18,8 +18,22 @@ public PeakDensityResearch(ITestOutputHelper output) {
     }
 
     [Fact]
-    public void Run() {
-        LoadPeakMap(out var bandedPeakRates);
+    public void Normal() {
+        Run("gabin-full-sigx-10.1.3.bin");
+    }
+
+    [Fact]
+    public void Fat() {
+        // Generated using libsigx.so from Android app v7.11
+        // SigType.SINGLE_FILE, SigOptions.FAT
+        // 'Fat' signature, presumably, contains raw peaks
+        // - before bin interpolation
+        // - before rate limit
+        Run("gabin-60s-sigx-5.1.0-fat.bin");
+    }
+
+    void Run(string fileName) {
+        LoadPeakMap(fileName, out var bandedPeakRates);
 
         for(var i = 0; i < bandedPeakRates.Count; i++)
             Output.WriteLine($"Band {i} peak rate {bandedPeakRates[i]:0.#} peak/sec");
@@ -70,8 +84,8 @@ public void Run() {
             Output.WriteLine($"{bin}\t{stripe}");
     }
 
-    void LoadPeakMap(out IReadOnlyList<double> bandedRates) {
-        var path = Path.Combine(TestHelper.DATA_DIR, "gabin-full-sigx-10.1.3.bin");
+    void LoadPeakMap(string fileName, out IReadOnlyList<double> bandedRates) {
+        var path = Path.Combine(TestHelper.DATA_DIR, fileName);
 
         Sig.Read(
             File.ReadAllBytes(path),

diff --git a/TestData/gabin-60s-sigx-5.1.0-fat.bin b/TestData/gabin-60s-sigx-5.1.0-fat.bin