[audio] Remove 'clac' noise when playing wave (javasound) (#2670)

* [audio] Remove 'clac' noise when playing wav (javasound)

A 'clac' can be heard at the beginning of a wav file when playing on the javasound sink.

Close #2669
Signed-off-by: Gwendal Roulleau <gwendal.roulleau@gmail.com>

bundles/org.openhab.core.audio/src/main/java/org/openhab/core/audio/internal/javasound/AudioPlayer.java

@@ -25,6 +25,7 @@ import javax.sound.sampled.SourceDataLine;
 import org.eclipse.jdt.annotation.NonNullByDefault;
 import org.eclipse.jdt.annotation.Nullable;
 import org.openhab.core.audio.AudioStream;
+import org.openhab.core.audio.utils.AudioWaveUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -60,7 +61,10 @@ public class AudioPlayer extends Thread {
     @Override
     public void run() {
         SourceDataLine line;
-        AudioFormat audioFormat = convertAudioFormat(this.audioStream.getFormat());
+
+        org.openhab.core.audio.AudioFormat openhabAudioFormat = audioStream.getFormat();
+
+        AudioFormat audioFormat = convertAudioFormat(openhabAudioFormat);
         if (audioFormat == null) {
             logger.warn("Audio format is unsupported or does not have enough details in order to be played");
             return;
@@ -87,6 +91,11 @@ public class AudioPlayer extends Thread {
         int nRead = 0;
         byte[] abData = new byte[65532]; // needs to be a multiple of 4 and 6, to support both 16 and 24 bit stereo
         try {
+            // If this is a wav container, we should remove the header from the stream
+            // to avoid a "clack" noise at the beginning
+            if (org.openhab.core.audio.AudioFormat.CONTAINER_WAVE.equals(openhabAudioFormat.getContainer())) {
+                AudioWaveUtils.removeFMT(audioStream);
+            }
             while (-1 != nRead) {
                 nRead = audioStream.read(abData, 0, abData.length);
                 if (nRead >= 0) {

bundles/org.openhab.core.audio/src/main/java/org/openhab/core/audio/utils/AudioWaveUtils.java

@@ -12,6 +12,7 @@
  */
 package org.openhab.core.audio.utils;
 
+import java.io.DataInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 
@@ -31,6 +32,11 @@ import org.openhab.core.audio.AudioFormat;
 @NonNullByDefault
 public class AudioWaveUtils {
 
+    /**
+     * This "magic" packet marks the beginning of the read data
+     */
+    private final static int DATA_MAGIC = 0x64617461;
+
     private static final AudioFormat DEFAULT_WAVE_AUDIO_FORMAT = new AudioFormat(AudioFormat.CONTAINER_WAVE,
             AudioFormat.CODEC_PCM_SIGNED, false, 16, 705600, 44100L, 1);
 
@@ -69,4 +75,26 @@ public class AudioWaveUtils {
             inputStream.reset();
         }
     }
+
+    /**
+     * Remove FMT block (WAV header) from a stream by consuming it until
+     * the magic packet signaling data. Limit to 200 readInt() (arbitrary value
+     * used in sun audio package).
+     * If you don't remove/consume the FMT and pass the data to a player
+     * as if it is a pure PCM stream, it could try to play it and will
+     * do a "click" noise at the beginning.
+     *
+     * @param audio A wav container in an InputStream
+     * @throws IOException
+     */
+    public static void removeFMT(InputStream data) throws IOException {
+        DataInputStream dataInputStream = new DataInputStream(data);
+        Integer nextInt = dataInputStream.readInt();
+        int i = 0;
+        while (nextInt != DATA_MAGIC && i < 200) {
+            nextInt = dataInputStream.readInt();
+            i++;
+        }
+        dataInputStream.readInt();
+    }
 }