Allow to copy audio tracks from the original video.

Author: danopdev

app/src/main/java/com/dan/videostab/MainFragment.kt

@@ -245,11 +245,15 @@ class MainFragment(activity: MainActivity) : AppFragment(activity) {
         val outputPath = getOutputPath()
 
         try {
-            val inputStream = File(tmpOutputVideo).inputStream()
-            val outputStream = File(outputPath).outputStream()
-            inputStream.copyTo(outputStream)
-            inputStream.close()
-            outputStream.close()
+            if (settings.keepAudio) {
+                VideoMerge.merge(outputPath, tmpOutputVideo, tmpInputVideo)
+            } else {
+                val inputStream = File(tmpOutputVideo).inputStream()
+                val outputStream = File(outputPath).outputStream()
+                inputStream.copyTo(outputStream)
+                inputStream.close()
+                outputStream.close()
+            }
 
             //Add it to gallery
             MediaScannerConnection.scanFile(context, arrayOf(outputPath), null, null)

app/src/main/java/com/dan/videostab/Settings.kt

@@ -42,6 +42,7 @@ class Settings( private val activity: Activity) {
     var algorithm: Int = ALGORITHM_GENERIC
     var strength: Int = 1
     var encoder: Int = ENCODER_H265
+    var keepAudio = false
 
     init {
         loadProperties()

app/src/main/java/com/dan/videostab/SettingsFragment.kt

@@ -19,13 +19,15 @@ class SettingsFragment(activity: MainActivity ) : AppFragment(activity) {
 
     override fun onBack(homeButton: Boolean) {
         settings.encoder = binding.videoEncoder.selectedItemPosition
+        settings.keepAudio = binding.switchKeepAudio.isChecked
         settings.saveProperties()
     }
 
     override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
         binding = SettingsFragmentBinding.inflate( inflater )
 
         binding.videoEncoder.setSelection(settings.encoder)
+        binding.switchKeepAudio.isChecked = settings.keepAudio
 
         return binding.root
     }

app/src/main/java/com/dan/videostab/VideoMerge.kt

@@ -0,0 +1,91 @@
+package com.dan.videostab
+
+import android.media.MediaCodec
+import android.media.MediaCodec.BufferInfo
+import android.media.MediaExtractor
+import android.media.MediaFormat
+import android.media.MediaMuxer
+import java.nio.ByteBuffer
+
+class VideoMerge {
+    companion object {
+        private const val BUFFER_SIZE = 1024 * 1024 //1 MB
+        private const val VIDEO_MIME_PREFIX = "video/"
+
+        private fun addTracks( muxer: MediaMuxer, sourceFile: String, filter: (String)->Boolean ) {
+            val extractor = MediaExtractor()
+            extractor.setDataSource(sourceFile)
+
+            for (sourceTrackIndex in 0 until extractor.trackCount) {
+                val trackFormat = extractor.getTrackFormat(sourceTrackIndex)
+                val trackMime = trackFormat.getString(MediaFormat.KEY_MIME) ?: continue
+                if (filter(trackMime)) muxer.addTrack(trackFormat)
+            }
+
+            extractor.release()
+        }
+
+        private fun copyTracks( muxer: MediaMuxer, sourceFile: String, buffer: ByteBuffer, startDestTrackIndex: Int, filter: (String)->Boolean ): Int {
+            val extractor = MediaExtractor()
+            val bufferInfo = BufferInfo()
+            var destTrackIndex = startDestTrackIndex
+
+            extractor.setDataSource(sourceFile)
+
+            for (sourceTrackIndex in 0 until extractor.trackCount) {
+                val trackFormat = extractor.getTrackFormat(sourceTrackIndex)
+                val trackMime = trackFormat.getString(MediaFormat.KEY_MIME) ?: continue
+                if (!filter(trackMime)) continue
+
+                extractor.selectTrack(sourceTrackIndex)
+
+                while(true) {
+                    val readSize = extractor.readSampleData(buffer, 0)
+                    if (readSize <= 0) break
+
+                    bufferInfo.set(
+                        0,
+                        readSize,
+                        extractor.sampleTime,
+                        if (0 != (extractor.sampleFlags and MediaExtractor.SAMPLE_FLAG_SYNC)) MediaCodec.BUFFER_FLAG_KEY_FRAME else 0)
+                    muxer.writeSampleData(destTrackIndex, buffer, bufferInfo)
+
+                    if (!extractor.advance()) break
+                }
+
+                bufferInfo.set(0, 0, extractor.sampleTime, MediaCodec.BUFFER_FLAG_END_OF_STREAM)
+                muxer.writeSampleData(destTrackIndex, buffer, bufferInfo)
+                destTrackIndex++
+            }
+
+            extractor.release()
+            return destTrackIndex
+        }
+
+        fun merge( outputFile: String, inputVideoFile: String, inputAudioFile: String ): Boolean {
+            var success = false
+            val buffer = ByteBuffer.allocate(BUFFER_SIZE)
+
+            try {
+                val muxer = MediaMuxer(outputFile, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4)
+                var startDestTrackIndex = 0
+
+                addTracks( muxer, inputVideoFile ) { mime -> mime.startsWith(VIDEO_MIME_PREFIX) }
+                addTracks( muxer, inputAudioFile ) { mime -> !mime.startsWith(VIDEO_MIME_PREFIX) }
+
+                muxer.start()
+
+                startDestTrackIndex = copyTracks( muxer, inputVideoFile, buffer, startDestTrackIndex ) { mime -> mime.startsWith(VIDEO_MIME_PREFIX) }
+                copyTracks( muxer, inputAudioFile, buffer, startDestTrackIndex ) { mime -> !mime.startsWith(VIDEO_MIME_PREFIX) }
+
+                muxer.stop()
+                muxer.release()
+                success = true
+            } catch (e: Exception) {
+                e.printStackTrace()
+            }
+
+            return success
+        }
+    }
+}

app/src/main/res/layout/settings_fragment.xml

@@ -37,6 +37,12 @@
                         android:entries="@array/video_encoder"
                         android:spinnerMode="dropdown" />
                 </LinearLayout>
+
+                <Switch
+                    android:id="@+id/switchKeepAudio"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:text="Keep audio" />
             </LinearLayout>
         </ScrollView>
     </LinearLayout>