Slooowpoke · January 25, 2024 20:26 · Dec 18, 2018 · Dec 18, 2018
diff --git a/WaveToPulseCodeModulation.java b/WaveToPulseCodeModulation.java
@@ -26,7 +26,7 @@ public WaveToPulseCodeModulation(String inputFile, String outputFile) throws IOE
      * The byte sequence marking the start of a PCM in a WAVE file is:
      * (64 61 74 61) = "data"
      *
-     * We search for the sequence and then create a file skipping the index
+     * We search for the sequence and then create a file by skipping file reading in the input file
      *
      * @return boolean
      * @throws IOException

diff --git a/WaveToPulseCodeModulation.java b/WaveToPulseCodeModulation.java
@@ -0,0 +1,112 @@
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+
+/**
+ * Creates a PCM file from a Wave (.wav) file
+ */
+public class WaveToPulseCodeModulation {
+
+    private File inputFile, outputFile;
+
+    private final int FAILED_SEARCH_INDEX = -99;
+
+    public WaveToPulseCodeModulation(String inputFile, String outputFile) throws IOException {
+        this.inputFile = new File(inputFile + ".wav");
+        this.outputFile = new File(outputFile + ".pcm");
+
+        // Create an empty output file
+        this.outputFile.createNewFile();
+    }
+
+    /**
+     * Converts a PCM to a WAVE by removing the Wave header
+     * First it needs to search for the start of the PCM
+     * The byte sequence marking the start of a PCM in a WAVE file is:
+     * (64 61 74 61) = "data"
+     *
+     * We search for the sequence and then create a file skipping the index
+     *
+     * @return boolean
+     * @throws IOException
+     */
+    public boolean convert() throws IOException {
+        // Stream in a byte array and look for a specific sequence
+        // Convert byte to int results in 64 = 100, 61 = 97, 74 = 116, 61= 97
+        int[] sequence = new int[]{100, 97, 116, 97};
+
+        // Generate an input stream
+        FileInputStream is = new FileInputStream(inputFile);
+
+        // Generate an output stream
+        FileOutputStream outputStream = new FileOutputStream(outputFile.getPath());
+
+        byte buffer[] = new byte[1024];
+
+        int read = 0;
+        int totalMatched = 0;
+        int indexToSkipHeader = 0;
+
+        while ((read = is.read(buffer)) > 0) {
+            indexToSkipHeader = findIndexOfSequenceInByteArray(sequence, buffer);
+
+            // If the index fails, keep searching
+            if(indexToSkipHeader == FAILED_SEARCH_INDEX){
+                continue;
+            }else{
+                break;
+            }
+        }
+
+        // Close the input stream and re-open it
+        is.close();
+        is = new FileInputStream(inputFile);
+
+        // Reset out reading variables
+        read = 0;
+
+        // Now use the indexToSkipHeader to skip a certain amount of bytes when reading it back out
+        is.skip(indexToSkipHeader);
+
+        while ((read = is.read(buffer)) > 0) {
+            outputStream.write(buffer);
+        }
+
+        System.out.println("Finished writing file");
+        return false;
+    }
+
+    /**
+     * Searches for the index of our sequence
+     * Returns the index of the sequence (total bytes to skip) or returns the failed index
+     *
+     * @param int[] sequence
+     * @param byte[] buffer
+     * @return int indexToSkip
+     */
+    private int findIndexOfSequenceInByteArray(int[] sequence, byte[] buffer){
+        int totalMatched = 0, indexToSkipHeader = 0;
+
+        // Search for first
+        for(byte value:buffer){
+            indexToSkipHeader++;
+
+            // Convert byte to an integer
+            int signed = value & 0xFF;
+
+            // Increase total matches if signed integer matches integer sequence
+            if(signed == sequence[totalMatched]){
+                totalMatched++;
+            }else{
+                totalMatched = 0;
+            }
+
+            // If the total matched is equal to the sequence length, we have found the index
+            if(totalMatched == sequence.length){
+                return indexToSkipHeader;
+            }
+        }
+        return FAILED_SEARCH_INDEX;
+    }
+}