Handle streaming audio as frames (#1244)

src/main/java/io/github/dsheirer/audio/convert/AudioFrames.java

@@ -0,0 +1,133 @@
+/*
+ * *****************************************************************************
+ * Copyright (C) 2014-2022 Dennis Sheirer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ * ****************************************************************************
+ */
+package io.github.dsheirer.audio.convert;
+
+import java.util.List;
+import org.apache.commons.math3.util.FastMath;
+
+public abstract class AudioFrames
+{
+    protected final int audioDuration;
+    protected final List<byte[]> audioFrames;
+    protected int mCurrentFrame = -1;
+
+    /**
+     * Create new AudioFrame
+     * @param audioDuration total duration in milliseconds
+     * @param audioFrames series of audio frames, split on frame boundaries
+     */
+    public AudioFrames(int audioDuration, List<byte[]> audioFrames)
+    {
+        this.audioDuration = audioDuration;
+        this.audioFrames = audioFrames;
+    }
+
+    /**
+     * Get total duration of frames
+     * @return total duration in milliseconds
+     */
+    public int getDuration()
+    {
+        return audioDuration;
+    }
+
+    /**
+     * Get all frames
+     * @return list of byte arrays, with each element representing a single frame of audio
+     */
+    public List<byte[]> getFrames()
+    {
+        return audioFrames;
+    }
+
+    /**
+     * Get current frame
+     * @return byte array with the current frame of audio
+     */
+    public byte[] getCurrentFrame()
+    {
+        return audioFrames.get(mCurrentFrame);
+    }
+
+    /**
+     * Get current frame duration
+     * @return frame duration in milliseconds
+     */
+    public abstract int getCurrentFrameDuration();
+
+    /**
+     * Indicates if there is a frame before the current one
+     * @return true if the frame exists, otherwise false
+     */
+    public boolean hasPrevFrame()
+    {
+        int prevFrame = mCurrentFrame - 1;
+        return prevFrame >= 0 && prevFrame < audioFrames.size();
+    }
+
+    /**
+     * Indicates if there is a frame after the current one
+     * @return true if the frame exists, otherwise false
+     */
+    public boolean hasNextFrame()
+    {
+        int nextFrame = mCurrentFrame + 1;
+        return nextFrame >= 0 && nextFrame < audioFrames.size();
+    }
+
+    /**
+     * Seek to the previous frame
+     */
+    public void prevFrame()
+    {
+        mCurrentFrame -= 1;
+    }
+
+    /**
+     * Seek to the next frame
+     */
+    public void nextFrame()
+    {
+        mCurrentFrame += 1;
+    }
+
+    /**
+     * Restart from beginning
+     * Must call nextFrame() to get first frame
+     */
+    public void restart()
+    {
+        mCurrentFrame = -1;
+    }
+
+    /**
+     * Seek by the specified time
+     * @param duration_ms time in milliseconds, positive or negative
+     */
+    public void seek(int duration_ms)
+    {
+        int step = duration_ms < 0 ? -1 : 1;
+        int actual_ms = 0;
+        while(FastMath.abs(actual_ms) < FastMath.abs(duration_ms))
+        {
+            mCurrentFrame += step;
+            actual_ms += getCurrentFrameDuration();
+        }
+    }
+}

src/main/java/io/github/dsheirer/audio/convert/ISilenceGenerator.java

@@ -22,5 +22,5 @@ import java.util.List;
 
 public interface ISilenceGenerator
 {
-    List<byte[]> generate(long duration);
+    AudioFrames generate(long duration);
 }

src/main/java/io/github/dsheirer/audio/convert/MP3AudioFrames.java

@@ -0,0 +1,46 @@
+/*
+ * *****************************************************************************
+ * Copyright (C) 2014-2022 Dennis Sheirer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ * ****************************************************************************
+ */
+
+package io.github.dsheirer.audio.convert;
+
+import java.util.List;
+
+public class MP3AudioFrames extends AudioFrames
+{
+
+    /**
+     * Create new MP3AudioFrame
+     * @param audioDuration total duration in milliseconds
+     * @param audioFrames series of audio frames, split on frame boundaries
+     */
+    public MP3AudioFrames(int audioDuration, List<byte[]> audioFrames)
+    {
+        super(audioDuration, audioFrames);
+    }
+
+    /**
+     * Get current frame duration
+     * @return frame duration in milliseconds
+     */
+    public int getCurrentFrameDuration()
+    {
+        return MP3Header.getFrameDuration(getCurrentFrame(), 0);
+    }
+
+}

src/main/java/io/github/dsheirer/audio/convert/MP3FrameInspector.java

@@ -55,6 +55,7 @@ public class MP3FrameInspector
         }
     }
 
+    /* TODO: Rework for MP3SilenceGenerator returning IAudioFrames
     public static void main(String[] args)
     {
         mLog.info("Starting ...");
@@ -66,4 +67,5 @@ public class MP3FrameInspector
 
         mLog.info("Finished");
     }
+    */
 }

src/main/java/io/github/dsheirer/audio/convert/MP3FrameTools.java

@@ -0,0 +1,59 @@
+/*
+ * *****************************************************************************
+ * Copyright (C) 2014-2022 Dennis Sheirer
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ * ****************************************************************************
+ */
+package io.github.dsheirer.audio.convert;
+
+import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.List;
+import org.apache.commons.math3.util.FastMath;
+
+public class MP3FrameTools {
+
+    private MP3FrameTools() {}
+
+    /**
+     * Split MP3 audio at frame boundaries
+     * @param input byte array of audio
+     * @return list of byte arrays containing audio frames
+     */
+    public static MP3AudioFrames split(byte[] input)
+    {
+        List<byte[]> mp3Frames = new ArrayList<>();
+        int audioDuration = 0;
+
+        int offset = 0;
+        while(offset < input.length)
+        {
+            if(MP3Header.hasSync(input, offset))
+            {
+                int framelen = MP3Header.getFrameLength(input, offset);
+                mp3Frames.add(Arrays.copyOfRange(input, offset, offset + FastMath.min(framelen, input.length - offset)));
+                audioDuration += MP3Header.getFrameDuration(input, offset);
+                offset += framelen;
+            }
+            else
+            {
+                offset += 1;
+            }
+        }
+
+        return new MP3AudioFrames(audioDuration, mp3Frames);
+    }
+
+}

src/main/java/io/github/dsheirer/audio/convert/MP3Header.java

@@ -19,6 +19,10 @@
 
 package io.github.dsheirer.audio.convert;
 
+import io.github.dsheirer.audio.convert.MPEGLayer;
+import io.github.dsheirer.audio.convert.MPEGVersion;
+import org.apache.commons.math3.util.FastMath;
+
 /**
  * Utility class for inspecting/parsing MP3 frames
  */
@@ -88,6 +92,71 @@ public class MP3Header
         return ChannelMode.fromValue((frame[offset + 3] & 0xC0) >> 6);
     }
 
+    /**
+     * Indicates if the frame has padding
+     * @param frame
+     * @param offset
+     * @return boolean
+     */
+    public static boolean isPadded(byte[] frame, int offset)
+    {
+        return (frame[offset + 2] & 0x01) == 1;
+    }
+
+    /**
+     * Get the number of bytes in the frame
+     * @param frame
+     * @param offset
+     * @return frame length in bytes
+     */
+    public static int getFrameLength(byte[] frame, int offset)
+    {
+        return (getFrameSamples(frame, offset) / 8) * (getBitRate(frame, offset) * 1000) / getSampleRate(frame, offset) + (isPadded(frame, offset) ? 1 : 0);
+    }
+
+    /**
+     * Get the number of samples in the frame
+     * @param frame
+     * @param offset
+     * @return length of frame in samples
+     */
+    public static int getFrameSamples(byte[] frame, int offset)
+    {
+        switch(getMPEGVersion(frame, offset))
+        {
+            case V_1:
+                switch(getMPEGLayer(frame, offset))
+                {
+                    case LAYER1: return 384;
+                    case LAYER2: return 1152;
+                    case LAYER3: return 1152;
+                    default:
+                }
+            case V_2:
+            case V_2_5:
+                switch(getMPEGLayer(frame, offset))
+                {
+                    case LAYER1: return 384;
+                    case LAYER2: return 1152;
+                    case LAYER3: return 576;
+                    default:
+                }
+            default:
+        }
+        return 0;
+    }
+
+    /**
+     * Get the frame duration in milliseconds
+     * @param frame
+     * @param offset
+     * @return duration in milliseconds
+     */
+    public static int getFrameDuration(byte[] frame, int offset)
+    {
+        return (int)FastMath.round((double)getFrameSamples(frame, offset) / (double)getSampleRate(frame, offset) * 1000);
+    }
+
     /**
      * Inspects the frame bytes and provides details about the header.
      */

src/main/java/io/github/dsheirer/audio/convert/MP3SilenceGenerator.java

@@ -19,19 +19,20 @@
 package io.github.dsheirer.audio.convert;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.apache.commons.math3.util.FastMath;
 
 public class MP3SilenceGenerator implements ISilenceGenerator
 {
     private final static Logger mLog = LoggerFactory.getLogger(MP3SilenceGenerator.class);
-    public static final int MP3_BIT_RATE = 16;
-    public static final boolean CONSTANT_BIT_RATE = false;
 
     private MP3AudioConverter mMP3AudioConverter;
     private InputAudioFormat mInputAudioFormat;
-    private byte[] mPreviousPartialFrameData;
+    private byte[] mSilenceFrame;
+    private int mSilenceFrameDuration;
 
     /**
      * Generates MP3 audio silence frames
@@ -40,19 +41,17 @@ public class MP3SilenceGenerator implements ISilenceGenerator
     {
         mInputAudioFormat = inputAudioFormat;
         mMP3AudioConverter = new MP3AudioConverter(inputAudioFormat, setting, false);
+        generate_frame();
     }
 
     /**
-     * Generates silence frames
-     * @param duration_ms in milliseconds
+     * Generates a single silence frame
      * @return
      */
-    public List<byte[]> generate(long duration_ms)
+    private void generate_frame()
     {
-        double duration_secs = (double)duration_ms / 1000.0;
-
         //We generate silence at 8000 kHz, because it gets resampled by the silence generator to the target rate
-        int length = (int)(duration_secs * InputAudioFormat.SR_8000.getSampleRate());
+        int length = (int)(InputAudioFormat.SR_8000.getSampleRate());
 
         List<float[]> silenceBuffers = new ArrayList<>();
 
@@ -64,7 +63,40 @@ public class MP3SilenceGenerator implements ISilenceGenerator
             added += chunk;
         }
 
-        return mMP3AudioConverter.convert(silenceBuffers);
+        List<byte[]> mp3Audio =  mMP3AudioConverter.convert(silenceBuffers);
+        byte[] silence = new byte[0];
+        for(byte[] mp3Chunk: mp3Audio)
+        {
+            silence = merge(silence, mp3Chunk);
+        }
+
+        MP3AudioFrames mp3Frames = MP3FrameTools.split(silence);
+        if(mp3Frames.hasNextFrame())
+        {
+            mp3Frames.nextFrame();
+            mSilenceFrame = mp3Frames.getCurrentFrame();
+            mSilenceFrameDuration = mp3Frames.getCurrentFrameDuration();
+        }
+
+    }
+
+    /**
+     * Generates silence frames
+     * @param duration_ms in milliseconds
+     * @return
+     */
+    public MP3AudioFrames generate(long duration_ms)
+    {
+        List<byte[]> silenceFrames = new ArrayList<>();
+        int silenceDuration = 0;
+
+        while(silenceDuration < duration_ms)
+        {
+            silenceFrames.add(mSilenceFrame);
+            silenceDuration += mSilenceFrameDuration;
+        }
+
+        return new MP3AudioFrames(silenceDuration, silenceFrames);
     }
 
     private static byte[] merge(byte[] a, byte[] b)
@@ -89,6 +121,7 @@ public class MP3SilenceGenerator implements ISilenceGenerator
         return c;
     }
 
+    /* TODO: Rework for MP3SilenceGenerator returning IAudioFrames
     public static void main(String[] args)
     {
         mLog.debug("Starting ...");
@@ -113,4 +146,5 @@ public class MP3SilenceGenerator implements ISilenceGenerator
 
         mLog.debug("Finished");
     }
+    */
 }