Post processing step

lib/src/main/java/com/otaliastudios/transcoder/TranscoderOptions.java

@@ -349,7 +349,9 @@ private List<DataSource> buildAudioDataSources()
                 if (dataSource.getTrackFormat(TrackType.AUDIO) != null) {
                     result.add(dataSource);
                 } else {
-                    result.add(new BlankAudioDataSource(dataSource.getDurationUs()));
+                    DataSource blankDataSource = new BlankAudioDataSource(dataSource.getDurationUs());
+                    blankDataSource.setPostProcessor(dataSource.getPostProcessor());
+                    result.add(blankDataSource);
                 }
             }
             return result;

lib/src/main/java/com/otaliastudios/transcoder/engine/Engine.java

@@ -20,10 +20,12 @@
 import com.otaliastudios.transcoder.TranscoderOptions;
 import com.otaliastudios.transcoder.internal.TrackTypeMap;
 import com.otaliastudios.transcoder.internal.ValidatorException;
+import com.otaliastudios.transcoder.postprocessor.AudioPostProcessor;
 import com.otaliastudios.transcoder.sink.DataSink;
 import com.otaliastudios.transcoder.sink.InvalidOutputFormatException;
 import com.otaliastudios.transcoder.source.DataSource;
 import com.otaliastudios.transcoder.strategy.TrackStrategy;
+import com.otaliastudios.transcoder.time.PresentationTime;
 import com.otaliastudios.transcoder.time.TimeInterpolator;
 import com.otaliastudios.transcoder.transcode.AudioTrackTranscoder;
 import com.otaliastudios.transcoder.transcode.NoOpTrackTranscoder;
@@ -70,6 +72,7 @@ public interface ProgressCallback {
     private final TrackTypeMap<MediaFormat> mOutputFormats = new TrackTypeMap<>();
     private volatile double mProgress;
     private final ProgressCallback mProgressCallback;
+    private final PresentationTime mAudioPresentationTime = new PresentationTime();
 
     public Engine(@Nullable ProgressCallback progressCallback) {
         mProgressCallback = progressCallback;
@@ -177,7 +180,9 @@ private void openCurrentStep(@NonNull TrackType type, @NonNull TranscoderOptions
                         transcoder = new AudioTrackTranscoder(dataSource, mDataSink,
                                 interpolator,
                                 options.getAudioStretcher(),
-                                options.getAudioResampler());
+                                options.getAudioResampler(),
+                                (AudioPostProcessor)dataSource.getPostProcessor(),
+                                mAudioPresentationTime);
                         break;
                     default:
                         throw new RuntimeException("Unknown type: " + type);
@@ -253,46 +258,55 @@ public long interpolate(@NonNull TrackType type, long time) {
         };
     }
 
-    private long getTrackDurationUs(@NonNull TrackType type) {
+    private long getTrackDurationUs(@NonNull TrackType type, boolean processedDuration) {
         if (!mStatuses.require(type).isTranscoding()) return 0L;
         int current = mCurrentStep.require(type);
         long totalDurationUs = 0;
         for (int i = 0; i < mDataSources.require(type).size(); i++) {
             DataSource source = mDataSources.require(type).get(i);
+            long dataSourceDurationUs;
             if (i < current) { // getReadUs() is a better approximation for sure.
-                totalDurationUs += source.getReadUs();
+                dataSourceDurationUs = source.getReadUs();
             } else {
-                totalDurationUs += source.getDurationUs();
+                dataSourceDurationUs = source.getDurationUs();
             }
+            if (processedDuration && source.getPostProcessor() != null) {
+                dataSourceDurationUs = source.getPostProcessor().calculateNewDurationUs(dataSourceDurationUs);
+            }
+            totalDurationUs += dataSourceDurationUs;
         }
         return totalDurationUs;
     }
 
     private long getTotalDurationUs() {
         boolean hasVideo = hasVideoSources() && mStatuses.requireVideo().isTranscoding();
         boolean hasAudio = hasAudioSources() && mStatuses.requireAudio().isTranscoding();
-        long video = hasVideo ? getTrackDurationUs(TrackType.VIDEO) : Long.MAX_VALUE;
-        long audio = hasAudio ? getTrackDurationUs(TrackType.AUDIO) : Long.MAX_VALUE;
+        long video = hasVideo ? getTrackDurationUs(TrackType.VIDEO, true) : Long.MAX_VALUE;
+        long audio = hasAudio ? getTrackDurationUs(TrackType.AUDIO, true) : Long.MAX_VALUE;
         return Math.min(video, audio);
     }
 
-    private long getTrackReadUs(@NonNull TrackType type) {
+    private long getTrackProgressUs(@NonNull TrackType type, boolean processedDuration) {
         if (!mStatuses.require(type).isTranscoding()) return 0L;
         int current = mCurrentStep.require(type);
         long completedDurationUs = 0;
         for (int i = 0; i < mDataSources.require(type).size(); i++) {
             DataSource source = mDataSources.require(type).get(i);
             if (i <= current) {
-                completedDurationUs += source.getReadUs();
+                long dataSourceReadUs = source.getReadUs();
+                if (processedDuration && source.getPostProcessor() != null) {
+                    dataSourceReadUs = source.getPostProcessor().calculateNewDurationUs(dataSourceReadUs);
+                }
+                completedDurationUs += dataSourceReadUs;
             }
         }
         return completedDurationUs;
     }
 
     private double getTrackProgress(@NonNull TrackType type) {
         if (!mStatuses.require(type).isTranscoding()) return 0.0D;
-        long readUs = getTrackReadUs(type);
-        long totalUs = getTotalDurationUs();
+        long readUs = getTrackProgressUs(type, false);
+        long totalUs = getTrackDurationUs(type, false);
         LOG.v("getTrackProgress - readUs:" + readUs + ", totalUs:" + totalUs);
         if (totalUs == 0) totalUs = 1; // Avoid NaN
         return (double) readUs / (double) totalUs;
@@ -361,8 +375,8 @@ public void transcode(@NonNull TranscoderOptions options) throws InterruptedExce
                 // This can happen, for example, if user adds 1 minute (video only) with 20 seconds
                 // of audio. The video track must be stopped once the audio stops.
                 long totalUs = getTotalDurationUs() + 100 /* tolerance */;
-                forceAudioEos = getTrackReadUs(TrackType.AUDIO) > totalUs;
-                forceVideoEos = getTrackReadUs(TrackType.VIDEO) > totalUs;
+                forceAudioEos = getTrackProgressUs(TrackType.AUDIO, true) > totalUs;
+                forceVideoEos = getTrackProgressUs(TrackType.VIDEO, true) > totalUs;
 
                 // Now step for transcoders that are not completed.
                 audioCompleted = isCompleted(TrackType.AUDIO);

lib/src/main/java/com/otaliastudios/transcoder/postprocessor/AudioPostProcessor.java

@@ -0,0 +1,16 @@
+package com.otaliastudios.transcoder.postprocessor;
+
+import androidx.annotation.NonNull;
+
+import java.nio.ShortBuffer;
+
+public interface AudioPostProcessor extends PostProcessor {
+    /**
+     * Manipulates the raw audio data inside inputBuffer and put the result in outputBuffer
+     * @param inputBuffer the input data (as raw audio data)
+     * @param outputBuffer the data after the manipulation
+     * @param bufferDurationUs the duration of the input data
+     * @return the duration of the output data
+     */
+    long postProcess(@NonNull final ShortBuffer inputBuffer, @NonNull final ShortBuffer outputBuffer, long bufferDurationUs);
+}

lib/src/main/java/com/otaliastudios/transcoder/postprocessor/DefaultAudioPostProcessor.java

@@ -0,0 +1,17 @@
+package com.otaliastudios.transcoder.postprocessor;
+
+import androidx.annotation.NonNull;
+import java.nio.ShortBuffer;
+
+public class DefaultAudioPostProcessor implements AudioPostProcessor {
+    @Override
+    public long calculateNewDurationUs(long durationUs) {
+        return durationUs;
+    }
+
+    @Override
+    public long postProcess(@NonNull ShortBuffer inputBuffer, @NonNull ShortBuffer outputBuffer, long bufferDurationUs) {
+        outputBuffer.put(inputBuffer);
+        return bufferDurationUs;
+    }
+}

lib/src/main/java/com/otaliastudios/transcoder/postprocessor/PostProcessor.java

@@ -0,0 +1,10 @@
+package com.otaliastudios.transcoder.postprocessor;
+
+public interface PostProcessor {
+    /**
+     * Returns the duration of the data source on it has been processed (after calling the postProcess() method)
+     * @param durationUs the original duratin in Us
+     * @return the new duration in Us
+     */
+    long calculateNewDurationUs(long durationUs);
+}

lib/src/main/java/com/otaliastudios/transcoder/postprocessor/VolumeAudioPostProcessor.java

@@ -0,0 +1,36 @@
+package com.otaliastudios.transcoder.postprocessor;
+
+import androidx.annotation.NonNull;
+
+import java.nio.ShortBuffer;
+
+public class VolumeAudioPostProcessor implements AudioPostProcessor {
+    private float mVolume;
+
+    public VolumeAudioPostProcessor(float volume) {
+        mVolume = volume;
+    }
+
+    @Override
+    public long calculateNewDurationUs(long durationUs) {
+        return durationUs;
+    }
+
+    private short applyVolume(short sample) {
+        float sampleAtVolume = sample * mVolume;
+        if (sampleAtVolume < Short.MIN_VALUE)
+            sampleAtVolume = Short.MIN_VALUE;
+        else if (sampleAtVolume > Short.MAX_VALUE)
+            sampleAtVolume = Short.MAX_VALUE;
+        return (short)sampleAtVolume;
+    }
+
+    @Override
+    public long postProcess(@NonNull ShortBuffer inputBuffer, @NonNull ShortBuffer outputBuffer, long bufferDurationUs) {
+        int inputRemaining = inputBuffer.remaining();
+        for (int i=0; i<inputRemaining; i++) {
+            outputBuffer.put(applyVolume(inputBuffer.get()));
+        }
+        return bufferDurationUs;
+    }
+}

lib/src/main/java/com/otaliastudios/transcoder/source/BlankAudioDataSource.java

@@ -6,6 +6,8 @@
 import androidx.annotation.Nullable;
 
 import com.otaliastudios.transcoder.engine.TrackType;
+import com.otaliastudios.transcoder.postprocessor.DefaultAudioPostProcessor;
+import com.otaliastudios.transcoder.postprocessor.PostProcessor;
 
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
@@ -46,6 +48,18 @@ public BlankAudioDataSource(long durationUs) {
         audioFormat.setInteger(MediaFormat.KEY_SAMPLE_RATE, SAMPLE_RATE);
     }
 
+    private PostProcessor postProcessor = new DefaultAudioPostProcessor();
+
+    @Override
+    public void setPostProcessor(@NonNull PostProcessor postProcessor) {
+        this.postProcessor = postProcessor;
+    }
+
+    @Override
+    public PostProcessor getPostProcessor() {
+        return postProcessor;
+    }
+
     @Override
     public int getOrientation() {
         return 0;

lib/src/main/java/com/otaliastudios/transcoder/source/DataSource.java

@@ -6,6 +6,7 @@
 import androidx.annotation.Nullable;
 
 import com.otaliastudios.transcoder.engine.TrackType;
+import com.otaliastudios.transcoder.postprocessor.PostProcessor;
 
 import java.nio.ByteBuffer;
 
@@ -14,6 +15,22 @@
  */
 public interface DataSource {
 
+    /**
+     * Returns an handler that need to be executed with the raw data source data
+     * before that it gets encoded.
+     *
+     * @return the PostProcessor object
+     */
+    PostProcessor getPostProcessor();
+
+    /**
+     * Sets the handler that needs to be called before that the raw data source data
+     * gets sent to the encoder.
+     *
+     * @param postProcessor the PostProcessor object
+     */
+    void setPostProcessor(@NonNull PostProcessor postProcessor);
+
     /**
      * Metadata information. Returns the video orientation, or 0.
      *

lib/src/main/java/com/otaliastudios/transcoder/source/DataSourceWrapper.java

@@ -7,6 +7,8 @@
 import androidx.annotation.Nullable;
 
 import com.otaliastudios.transcoder.engine.TrackType;
+import com.otaliastudios.transcoder.postprocessor.DefaultAudioPostProcessor;
+import com.otaliastudios.transcoder.postprocessor.PostProcessor;
 
 /**
  * A {@link DataSource} wrapper that simply delegates all methods to the
@@ -26,6 +28,18 @@ protected DataSource getSource() {
         return mSource;
     }
 
+    private PostProcessor postProcessor = new DefaultAudioPostProcessor();
+
+    @Override
+    public void setPostProcessor(@NonNull PostProcessor postProcessor) {
+        this.postProcessor = postProcessor;
+    }
+
+    @Override
+    public PostProcessor getPostProcessor() {
+        return postProcessor;
+    }
+
     @Override
     public int getOrientation() {
         return mSource.getOrientation();

lib/src/main/java/com/otaliastudios/transcoder/source/DefaultDataSource.java

@@ -12,6 +12,8 @@
 import com.otaliastudios.transcoder.internal.ISO6709LocationParser;
 import com.otaliastudios.transcoder.internal.Logger;
 import com.otaliastudios.transcoder.internal.TrackTypeMap;
+import com.otaliastudios.transcoder.postprocessor.DefaultAudioPostProcessor;
+import com.otaliastudios.transcoder.postprocessor.PostProcessor;
 
 import java.io.IOException;
 import java.util.HashSet;
@@ -58,6 +60,18 @@ private void ensureExtractor() {
 
     protected abstract void applyRetriever(@NonNull MediaMetadataRetriever retriever);
 
+    private PostProcessor postProcessor = new DefaultAudioPostProcessor();
+
+    @Override
+    public void setPostProcessor(@NonNull PostProcessor postProcessor) {
+        this.postProcessor = postProcessor;
+    }
+
+    @Override
+    public PostProcessor getPostProcessor() {
+        return postProcessor;
+    }
+
     @Override
     public void selectTrack(@NonNull TrackType type) {
         mSelectedTracks.add(type);

lib/src/main/java/com/otaliastudios/transcoder/time/PresentationTime.java

@@ -0,0 +1,11 @@
+package com.otaliastudios.transcoder.time;
+
+public class PresentationTime {
+    private long mTotalEncoderDurationUs = 0;
+    public void increaseEncoderDuration(long encoderDurationUs) {
+        mTotalEncoderDurationUs += encoderDurationUs;
+    }
+    public long getEncoderPresentationTimeUs() {
+        return mTotalEncoderDurationUs;
+    }
+}

lib/src/main/java/com/otaliastudios/transcoder/transcode/AudioTrackTranscoder.java

@@ -8,10 +8,12 @@
 
 import com.otaliastudios.transcoder.engine.TrackType;
 import com.otaliastudios.transcoder.internal.MediaCodecBuffers;
+import com.otaliastudios.transcoder.postprocessor.AudioPostProcessor;
 import com.otaliastudios.transcoder.resample.AudioResampler;
 import com.otaliastudios.transcoder.sink.DataSink;
 import com.otaliastudios.transcoder.source.DataSource;
 import com.otaliastudios.transcoder.stretch.AudioStretcher;
+import com.otaliastudios.transcoder.time.PresentationTime;
 import com.otaliastudios.transcoder.time.TimeInterpolator;
 import com.otaliastudios.transcoder.transcode.internal.AudioEngine;
 
@@ -20,8 +22,10 @@
 public class AudioTrackTranscoder extends BaseTrackTranscoder {
 
     private TimeInterpolator mTimeInterpolator;
+    private PresentationTime mPresentationTime;
     private AudioStretcher mAudioStretcher;
     private AudioResampler mAudioResampler;
+    private AudioPostProcessor mAudioPostProcessor;
     private AudioEngine mAudioEngine;
     private MediaCodec mEncoder; // to create the channel
     private MediaFormat mEncoderOutputFormat; // to create the channel
@@ -30,11 +34,15 @@ public AudioTrackTranscoder(@NonNull DataSource dataSource,
                                 @NonNull DataSink dataSink,
                                 @NonNull TimeInterpolator timeInterpolator,
                                 @NonNull AudioStretcher audioStretcher,
-                                @NonNull AudioResampler audioResampler) {
+                                @NonNull AudioResampler audioResampler,
+                                @NonNull AudioPostProcessor audioPostProcessor,
+                                @NonNull PresentationTime presentationTime) {
         super(dataSource, dataSink, TrackType.AUDIO);
         mTimeInterpolator = timeInterpolator;
         mAudioStretcher = audioStretcher;
         mAudioResampler = audioResampler;
+        mAudioPostProcessor = audioPostProcessor;
+        mPresentationTime = presentationTime;
     }
 
     @Override
@@ -57,7 +65,9 @@ protected void onDecoderOutputFormatChanged(@NonNull MediaCodec decoder, @NonNul
                 mEncoder, mEncoderOutputFormat,
                 mTimeInterpolator,
                 mAudioStretcher,
-                mAudioResampler);
+                mAudioResampler,
+                mAudioPostProcessor,
+                mPresentationTime);
         mEncoder = null;
         mEncoderOutputFormat = null;
         mTimeInterpolator = null;