Take period start time into account when calculating segment times.

library/src/main/java/com/google/android/exoplayer/dash/DashChunkSource.java

@@ -531,7 +531,8 @@ public class DashChunkSource implements ChunkSource {
       if (initializationChunk.hasSeekMap()) {
         representationHolder.segmentIndex = new DashWrappingSegmentIndex(
             (ChunkIndex) initializationChunk.getSeekMap(),
-            initializationChunk.dataSpec.uri.toString());
+            initializationChunk.dataSpec.uri.toString(),
+            representationHolder.representation.periodStartMs * 1000);
       }
       // The null check avoids overwriting drmInitData obtained from the manifest with drmInitData
       // obtained from the stream, as per DASH IF Interoperability Recommendations V3.0, 7.5.3.
@@ -638,7 +639,8 @@ public class DashChunkSource implements ChunkSource {
     DataSpec dataSpec = new DataSpec(segmentUri.getUri(), segmentUri.start, segmentUri.length,
         representation.getCacheKey());
 
-    long sampleOffsetUs = -1 * representation.presentationTimeOffsetUs;
+    long sampleOffsetUs = representation.periodStartMs * 1000
+        - representation.presentationTimeOffsetUs;
     if (representation.format.mimeType.equals(MimeTypes.TEXT_VTT)) {
       if (representationHolder.vttHeaderOffsetUs != sampleOffsetUs) {
         // Update the VTT header.

library/src/main/java/com/google/android/exoplayer/dash/DashWrappingSegmentIndex.java

@@ -26,14 +26,17 @@ public class DashWrappingSegmentIndex implements DashSegmentIndex {
 
   private final ChunkIndex chunkIndex;
   private final String uri;
+  private final long startTimeUs;
 
   /**
    * @param chunkIndex The {@link ChunkIndex} to wrap.
    * @param uri The URI where the data is located.
+   * @param startTimeUs The start time of the index, in microseconds.
    */
-  public DashWrappingSegmentIndex(ChunkIndex chunkIndex, String uri) {
+  public DashWrappingSegmentIndex(ChunkIndex chunkIndex, String uri, long startTimeUs) {
     this.chunkIndex = chunkIndex;
     this.uri = uri;
+    this.startTimeUs = startTimeUs;
   }
 
   @Override
@@ -48,7 +51,7 @@ public class DashWrappingSegmentIndex implements DashSegmentIndex {
 
   @Override
   public long getTimeUs(int segmentNum) {
-    return chunkIndex.timesUs[segmentNum];
+    return chunkIndex.timesUs[segmentNum] + startTimeUs;
   }
 
   @Override
@@ -63,7 +66,7 @@ public class DashWrappingSegmentIndex implements DashSegmentIndex {
 
   @Override
   public int getSegmentNum(long timeUs) {
-    return chunkIndex.getChunkIndex(timeUs);
+    return chunkIndex.getChunkIndex(timeUs - startTimeUs);
   }
 
   @Override

library/src/main/java/com/google/android/exoplayer/dash/mpd/Representation.java

@@ -266,12 +266,12 @@ public abstract class Representation implements FormatWrapper {
 
     @Override
     public int getSegmentNum(long timeUs) {
-      return segmentBase.getSegmentNum(timeUs);
+      return segmentBase.getSegmentNum(timeUs - periodStartMs * 1000);
     }
 
     @Override
     public long getTimeUs(int segmentIndex) {
-      return segmentBase.getSegmentTimeUs(segmentIndex);
+      return segmentBase.getSegmentTimeUs(segmentIndex) + periodStartMs * 1000;
     }
 
     @Override