add Track interleaving

amethyst/src/main/java/com/vitorpamplona/amethyst/service/uploads/MetadataStripper.kt

@@ -154,8 +154,8 @@ class MetadataStripper {
                 val trackIndexMap = mutableMapOf<Int, Int>()
                 for (i in 0 until extractor.trackCount) {
                     val format = extractor.getTrackFormat(i)
-                    val newTrackIndex = muxer.addTrack(format)
+                    trackIndexMap[i] = muxer.addTrack(format)
-                    trackIndexMap[i] = newTrackIndex
+                    extractor.selectTrack(i)
                 }
 
                 muxer.start()
@@ -165,14 +165,12 @@ class MetadataStripper {
                 val buffer = java.nio.ByteBuffer.allocate(bufferSize)
                 val bufferInfo = MediaCodec.BufferInfo()
 
-                for (i in 0 until extractor.trackCount) {
-                    extractor.selectTrack(i)
-                    val outputTrack = trackIndexMap[i] ?: continue
-
                 while (true) {
                     val sampleSize = extractor.readSampleData(buffer, 0)
                     if (sampleSize < 0) break
 
+                    val outputTrack = trackIndexMap[extractor.sampleTrackIndex] ?: break
+
                     bufferInfo.offset = 0
                     bufferInfo.size = sampleSize
                     bufferInfo.presentationTimeUs = extractor.sampleTime
@@ -182,9 +180,6 @@ class MetadataStripper {
                     extractor.advance()
                 }
 
-                    extractor.unselectTrack(i)
-                }
-
                 muxer.stop()
                 muxerStarted = false
                 succeeded = true