Define DashSegmentIndex wrapper.

This paves the way for SegmentTemplate and SegmentList based
mpds, which will implement DashSegmentIndex directly rather than
parsing an index from the media stream.

- Define DashSegmentIndex.
- Make use of DashSegmentIndex in chunk sources.
- Define an implementation of DashSegmentIndex that wraps a SegmentIndex.
- Add method that will allow Representations to return a DashSegmentIndex
  directly in the future.
- Add support for non-contiguous index and initialization data in media streams.
  For the Webm case this isn't enabled yet due to extractor limitations.
- Removed ability to fetch multiple chunks. This functionality does not extend
  properly to SegmentList and SegmentTemplate variants of DASH.

demo/src/main/java/com/google/android/exoplayer/demo/Samples.java

@@ -129,6 +129,10 @@ package com.google.android.exoplayer.demo;
         + "as=fmp4_audio_cenc,fmp4_sd_hd_cenc&sparams=ip,ipbits,expire,as&ip=0.0.0.0&ipbits=0"
         + "&expire=19000000000&signature=88DC53943385CED8CF9F37ADD9E9843E3BF621E6."
         + "22727BB612D24AA4FACE4EF62726F9461A9BF57A&key=ik0", DemoUtil.TYPE_DASH_VOD, true, true),
+        new Sample("WV: 30s license duration", "f9a34cab7b05881a",
+            "http://dash.edgesuite.net/digitalprimates/fraunhofer/480p_video/heaac_2_0_with_video/ElephantsDream/elephants_dream_480p_heaac2_0.mpd", DemoUtil.TYPE_DASH_VOD, false, true),
+        
+        
   };
 
   public static final Sample[] MISC = new Sample[] {

library/src/main/java/com/google/android/exoplayer/chunk/Format.java

@@ -100,6 +100,11 @@ public class Format {
     this.bandwidth = bitrate / 8;
   }
 
+  @Override
+  public int hashCode() {
+    return id.hashCode();
+  }
+
   /**
    * Implements equality based on {@link #id} only.
    */

library/src/main/java/com/google/android/exoplayer/dash/DashMp4ChunkSource.java

@@ -27,15 +27,14 @@ import com.google.android.exoplayer.chunk.FormatEvaluator;
 import com.google.android.exoplayer.chunk.FormatEvaluator.Evaluation;
 import com.google.android.exoplayer.chunk.MediaChunk;
 import com.google.android.exoplayer.chunk.Mp4MediaChunk;
+import com.google.android.exoplayer.dash.mpd.RangedUri;
 import com.google.android.exoplayer.dash.mpd.Representation;
-import com.google.android.exoplayer.parser.SegmentIndex;
 import com.google.android.exoplayer.parser.mp4.FragmentedMp4Extractor;
 import com.google.android.exoplayer.upstream.DataSource;
 import com.google.android.exoplayer.upstream.DataSpec;
 import com.google.android.exoplayer.upstream.NonBlockingInputStream;
-import com.google.android.exoplayer.util.Util;
 
-import android.util.Log;
+import android.net.Uri;
 
 import java.io.IOException;
 import java.util.Arrays;
@@ -47,26 +46,17 @@ import java.util.List;
  */
 public class DashMp4ChunkSource implements ChunkSource {
 
-  public static final int DEFAULT_NUM_SEGMENTS_PER_CHUNK = 1;
-
-  private static final int EXPECTED_INITIALIZATION_RESULT =
-      FragmentedMp4Extractor.RESULT_END_OF_STREAM
-      | FragmentedMp4Extractor.RESULT_READ_MOOV
-      | FragmentedMp4Extractor.RESULT_READ_SIDX;
-
-  private static final String TAG = "DashMp4ChunkSource";
-
   private final TrackInfo trackInfo;
   private final DataSource dataSource;
   private final FormatEvaluator evaluator;
   private final Evaluation evaluation;
   private final int maxWidth;
   private final int maxHeight;
-  private final int numSegmentsPerChunk;
 
   private final Format[] formats;
   private final HashMap<String, Representation> representations;
   private final HashMap<String, FragmentedMp4Extractor> extractors;
+  private final HashMap<String, DashSegmentIndex> segmentIndexes;
 
   private boolean lastChunkWasInitialization;
 
@@ -77,23 +67,11 @@ public class DashMp4ChunkSource implements ChunkSource {
    */
   public DashMp4ChunkSource(DataSource dataSource, FormatEvaluator evaluator,
       Representation... representations) {
-    this(dataSource, evaluator, DEFAULT_NUM_SEGMENTS_PER_CHUNK, representations);
-  }
-
-  /**
-   * @param dataSource A {@link DataSource} suitable for loading the media data.
-   * @param evaluator Selects from the available formats.
-   * @param numSegmentsPerChunk The number of segments (as defined in the stream's segment index)
-   *     that should be grouped into a single chunk.
-   * @param representations The representations to be considered by the source.
-   */
-  public DashMp4ChunkSource(DataSource dataSource, FormatEvaluator evaluator,
-      int numSegmentsPerChunk, Representation... representations) {
     this.dataSource = dataSource;
     this.evaluator = evaluator;
-    this.numSegmentsPerChunk = numSegmentsPerChunk;
     this.formats = new Format[representations.length];
     this.extractors = new HashMap<String, FragmentedMp4Extractor>();
+    this.segmentIndexes = new HashMap<String, DashSegmentIndex>();
     this.representations = new HashMap<String, Representation>();
     this.trackInfo = new TrackInfo(representations[0].format.mimeType,
         representations[0].periodDuration * 1000);
@@ -106,6 +84,10 @@ public class DashMp4ChunkSource implements ChunkSource {
       maxHeight = Math.max(formats[i].height, maxHeight);
       extractors.put(formats[i].id, new FragmentedMp4Extractor());
       this.representations.put(formats[i].id, representations[i]);
+      DashSegmentIndex segmentIndex = representations[i].getIndex();
+      if (segmentIndex != null) {
+        segmentIndexes.put(formats[i].id, segmentIndex);
+      }
     }
     this.maxWidth = maxWidth;
     this.maxHeight = maxHeight;
@@ -161,29 +143,39 @@ public class DashMp4ChunkSource implements ChunkSource {
 
     Representation selectedRepresentation = representations.get(selectedFormat.id);
     FragmentedMp4Extractor extractor = extractors.get(selectedRepresentation.format.id);
+
+    RangedUri pendingInitializationUri = null;
+    RangedUri pendingIndexUri = null;
     if (extractor.getTrack() == null) {
-      Chunk initializationChunk = newInitializationChunk(selectedRepresentation, extractor,
+      pendingInitializationUri = selectedRepresentation.getInitializationUri();
-          dataSource, evaluation.trigger);
+    }
+    if (!segmentIndexes.containsKey(selectedRepresentation.format.id)) {
+      pendingIndexUri = selectedRepresentation.getIndexUri();
+    }
+    if (pendingInitializationUri != null || pendingIndexUri != null) {
+      // We have initialization and/or index requests to make.
+      Chunk initializationChunk = newInitializationChunk(pendingInitializationUri, pendingIndexUri,
+          selectedRepresentation, extractor, dataSource, evaluation.trigger);
       lastChunkWasInitialization = true;
       out.chunk = initializationChunk;
       return;
     }
 
-    int nextIndex;
+    int nextSegmentNum;
+    DashSegmentIndex segmentIndex = segmentIndexes.get(selectedRepresentation.format.id);
     if (queue.isEmpty()) {
-      nextIndex = Util.binarySearchFloor(extractor.getSegmentIndex().timesUs, seekPositionUs,
+      nextSegmentNum = segmentIndex.getSegmentNum(seekPositionUs);
-          true, true);
     } else {
-      nextIndex = queue.get(out.queueSize - 1).nextChunkIndex;
+      nextSegmentNum = queue.get(out.queueSize - 1).nextChunkIndex;
     }
 
-    if (nextIndex == -1) {
+    if (nextSegmentNum == -1) {
       out.chunk = null;
       return;
     }
 
-    Chunk nextMediaChunk = newMediaChunk(selectedRepresentation, extractor, dataSource,
+    Chunk nextMediaChunk = newMediaChunk(selectedRepresentation, segmentIndex, extractor,
-        extractor.getSegmentIndex(), nextIndex, evaluation.trigger, numSegmentsPerChunk);
+        dataSource, nextSegmentNum, evaluation.trigger);
     lastChunkWasInitialization = false;
     out.chunk = nextMediaChunk;
   }
@@ -198,75 +190,75 @@ public class DashMp4ChunkSource implements ChunkSource {
     // Do nothing.
   }
 
-  private static Chunk newInitializationChunk(Representation representation,
+  private Chunk newInitializationChunk(RangedUri initializationUri, RangedUri indexUri,
-      FragmentedMp4Extractor extractor, DataSource dataSource, int trigger) {
+      Representation representation, FragmentedMp4Extractor extractor, DataSource dataSource,
-    DataSpec dataSpec = new DataSpec(representation.uri, 0, representation.indexEnd + 1,
+      int trigger) {
+    int expectedExtractorResult = FragmentedMp4Extractor.RESULT_END_OF_STREAM;
+    long indexAnchor = 0;
+    RangedUri requestUri;
+    if (initializationUri != null) {
+      // It's common for initialization and index data to be stored adjacently. Attempt to merge
+      // the two requests together to request at once.
+      expectedExtractorResult |= FragmentedMp4Extractor.RESULT_READ_MOOV;
+      requestUri = initializationUri.attemptMerge(indexUri);
+      if (requestUri != null) {
+        expectedExtractorResult |= FragmentedMp4Extractor.RESULT_READ_SIDX;
+        indexAnchor = indexUri.start + indexUri.length;
+      } else {
+        requestUri = initializationUri;
+      }
+    } else {
+      requestUri = indexUri;
+      indexAnchor = indexUri.start + indexUri.length;
+      expectedExtractorResult |= FragmentedMp4Extractor.RESULT_READ_SIDX;
+    }
+    DataSpec dataSpec = new DataSpec(requestUri.getUri(), requestUri.start, requestUri.length,
         representation.getCacheKey());
-    return new InitializationMp4Loadable(dataSource, dataSpec, trigger, extractor, representation);
+    return new InitializationMp4Loadable(dataSource, dataSpec, trigger, representation.format,
+        extractor, expectedExtractorResult, indexAnchor);
   }
 
-  private static Chunk newMediaChunk(Representation representation,
+  private Chunk newMediaChunk(Representation representation, DashSegmentIndex segmentIndex,
-      FragmentedMp4Extractor extractor, DataSource dataSource, SegmentIndex sidx, int index,
+      FragmentedMp4Extractor extractor, DataSource dataSource, int segmentNum, int trigger) {
-      int trigger, int numSegmentsPerChunk) {
+    int lastSegmentNum = segmentIndex.getLastSegmentNum();
-
+    int nextSegmentNum = segmentNum == lastSegmentNum ? -1 : segmentNum + 1;
-    // Computes the segments to included in the next fetch.
+    long startTimeUs = segmentIndex.getTimeUs(segmentNum);
-    int numSegmentsToFetch = Math.min(numSegmentsPerChunk, sidx.length - index);
+    long endTimeUs = segmentNum < lastSegmentNum ? segmentIndex.getTimeUs(segmentNum + 1)
-    int lastSegmentInChunk = index + numSegmentsToFetch - 1;
+        : startTimeUs + segmentIndex.getDurationUs(segmentNum);
-    int nextIndex = lastSegmentInChunk == sidx.length - 1 ? -1 : lastSegmentInChunk + 1;
+    RangedUri segmentUri = segmentIndex.getSegmentUrl(segmentNum);
-
+    DataSpec dataSpec = new DataSpec(segmentUri.getUri(), segmentUri.start, segmentUri.length,
-    long startTimeUs = sidx.timesUs[index];
-
-    // Compute the end time, prefer to use next segment start time if there is a next segment.
-    long endTimeUs = nextIndex == -1 ?
-      sidx.timesUs[lastSegmentInChunk] + sidx.durationsUs[lastSegmentInChunk] :
-      sidx.timesUs[nextIndex];
-
-    long offset = (int) representation.indexEnd + 1 + sidx.offsets[index];
-
-    // Compute combined segments byte length.
-    long size = 0;
-    for (int i = index; i <= lastSegmentInChunk; i++) {
-      size += sidx.sizes[i];
-    }
-
-    DataSpec dataSpec = new DataSpec(representation.uri, offset, size,
         representation.getCacheKey());
     return new Mp4MediaChunk(dataSource, dataSpec, representation.format, trigger, startTimeUs,
-        endTimeUs, nextIndex, extractor, false, 0);
+        endTimeUs, nextSegmentNum, extractor, false, 0);
   }
 
-  private static class InitializationMp4Loadable extends Chunk {
+  private class InitializationMp4Loadable extends Chunk {
 
-    private final Representation representation;
     private final FragmentedMp4Extractor extractor;
+    private final int expectedExtractorResult;
+    private final long indexAnchor;
+    private final Uri uri;
 
     public InitializationMp4Loadable(DataSource dataSource, DataSpec dataSpec, int trigger,
-        FragmentedMp4Extractor extractor, Representation representation) {
+        Format format, FragmentedMp4Extractor extractor, int expectedExtractorResult,
-      super(dataSource, dataSpec, representation.format, trigger);
+        long indexAnchor) {
+      super(dataSource, dataSpec, format, trigger);
       this.extractor = extractor;
-      this.representation = representation;
+      this.expectedExtractorResult = expectedExtractorResult;
+      this.indexAnchor = indexAnchor;
+      this.uri = dataSpec.uri;
     }
 
     @Override
     protected void consumeStream(NonBlockingInputStream stream) throws IOException {
       int result = extractor.read(stream, null);
-      if (result != EXPECTED_INITIALIZATION_RESULT) {
+      if (result != expectedExtractorResult) {
-        throw new ParserException("Invalid initialization data");
+        throw new ParserException("Invalid extractor result. Expected "
+            + expectedExtractorResult + ", got " + result);
       }
-      validateSegmentIndex(extractor.getSegmentIndex());
+      if ((result & FragmentedMp4Extractor.RESULT_READ_SIDX) != 0) {
-    }
+        segmentIndexes.put(format.id,
-
+            new DashWrappingSegmentIndex(extractor.getSegmentIndex(), uri, indexAnchor));
-    private void validateSegmentIndex(SegmentIndex segmentIndex) {
-      long expectedIndexLen = representation.indexEnd - representation.indexStart + 1;
-      if (segmentIndex.sizeBytes != expectedIndexLen) {
-        Log.w(TAG, "Sidx length mismatch: sidxLen = " + segmentIndex.sizeBytes +
-            ", ExpectedLen = " + expectedIndexLen);
-      }
-      long sidxContentLength = segmentIndex.offsets[segmentIndex.length - 1] +
-          segmentIndex.sizes[segmentIndex.length - 1] + representation.indexEnd + 1;
-      if (sidxContentLength != representation.contentLength) {
-        Log.w(TAG, "ContentLength mismatch: Actual = " + sidxContentLength +
-          ", Expected = " + representation.contentLength);
       }
     }
 

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

@@ -27,16 +27,15 @@ import com.google.android.exoplayer.chunk.FormatEvaluator;
 import com.google.android.exoplayer.chunk.FormatEvaluator.Evaluation;
 import com.google.android.exoplayer.chunk.MediaChunk;
 import com.google.android.exoplayer.chunk.WebmMediaChunk;
+import com.google.android.exoplayer.dash.mpd.RangedUri;
 import com.google.android.exoplayer.dash.mpd.Representation;
-import com.google.android.exoplayer.parser.SegmentIndex;
 import com.google.android.exoplayer.parser.webm.DefaultWebmExtractor;
 import com.google.android.exoplayer.parser.webm.WebmExtractor;
 import com.google.android.exoplayer.upstream.DataSource;
 import com.google.android.exoplayer.upstream.DataSpec;
 import com.google.android.exoplayer.upstream.NonBlockingInputStream;
-import com.google.android.exoplayer.util.Util;
 
-import android.util.Log;
+import android.net.Uri;
 
 import java.io.IOException;
 import java.util.Arrays;
@@ -48,34 +47,27 @@ import java.util.List;
  */
 public class DashWebmChunkSource implements ChunkSource {
 
-  private static final String TAG = "DashWebmChunkSource";
-
   private final TrackInfo trackInfo;
   private final DataSource dataSource;
   private final FormatEvaluator evaluator;
   private final Evaluation evaluation;
   private final int maxWidth;
   private final int maxHeight;
-  private final int numSegmentsPerChunk;
 
   private final Format[] formats;
   private final HashMap<String, Representation> representations;
   private final HashMap<String, WebmExtractor> extractors;
+  private final HashMap<String, DashSegmentIndex> segmentIndexes;
 
   private boolean lastChunkWasInitialization;
 
-  public DashWebmChunkSource(
-      DataSource dataSource, FormatEvaluator evaluator, Representation... representations) {
-    this(dataSource, evaluator, 1, representations);
-  }
-
   public DashWebmChunkSource(DataSource dataSource, FormatEvaluator evaluator,
-      int numSegmentsPerChunk, Representation... representations) {
+      Representation... representations) {
     this.dataSource = dataSource;
     this.evaluator = evaluator;
-    this.numSegmentsPerChunk = numSegmentsPerChunk;
     this.formats = new Format[representations.length];
     this.extractors = new HashMap<String, WebmExtractor>();
+    this.segmentIndexes = new HashMap<String, DashSegmentIndex>();
     this.representations = new HashMap<String, Representation>();
     this.trackInfo = new TrackInfo(
         representations[0].format.mimeType, representations[0].periodDuration * 1000);
@@ -88,6 +80,10 @@ public class DashWebmChunkSource implements ChunkSource {
       maxHeight = Math.max(formats[i].height, maxHeight);
       extractors.put(formats[i].id, new DefaultWebmExtractor());
       this.representations.put(formats[i].id, representations[i]);
+      DashSegmentIndex segmentIndex = representations[i].getIndex();
+      if (segmentIndex != null) {
+        segmentIndexes.put(formats[i].id, segmentIndex);
+      }
     }
     this.maxWidth = maxWidth;
     this.maxHeight = maxHeight;
@@ -143,28 +139,34 @@ public class DashWebmChunkSource implements ChunkSource {
 
     Representation selectedRepresentation = representations.get(selectedFormat.id);
     WebmExtractor extractor = extractors.get(selectedRepresentation.format.id);
+
     if (!extractor.isPrepared()) {
-      Chunk initializationChunk = newInitializationChunk(selectedRepresentation, extractor,
+      // TODO: This code forces cues to exist and to immediately follow the initialization
-          dataSource, evaluation.trigger);
+      // data. Webm extractor should be generalized to allow cues to be optional. See [redacted].
+      RangedUri initializationUri = selectedRepresentation.getInitializationUri().attemptMerge(
+           selectedRepresentation.getIndexUri());
+      Chunk initializationChunk = newInitializationChunk(initializationUri, selectedRepresentation,
+          extractor, dataSource, evaluation.trigger);
       lastChunkWasInitialization = true;
       out.chunk = initializationChunk;
       return;
     }
 
-    int nextIndex;
+    int nextSegmentNum;
+    DashSegmentIndex segmentIndex = segmentIndexes.get(selectedRepresentation.format.id);
     if (queue.isEmpty()) {
-      nextIndex = Util.binarySearchFloor(extractor.getCues().timesUs, seekPositionUs, true, true);
+      nextSegmentNum = segmentIndex.getSegmentNum(seekPositionUs);
     } else {
-      nextIndex = queue.get(out.queueSize - 1).nextChunkIndex;
+      nextSegmentNum = queue.get(out.queueSize - 1).nextChunkIndex;
     }
 
-    if (nextIndex == -1) {
+    if (nextSegmentNum == -1) {
       out.chunk = null;
       return;
     }
 
-    Chunk nextMediaChunk = newMediaChunk(selectedRepresentation, extractor, dataSource,
+    Chunk nextMediaChunk = newMediaChunk(selectedRepresentation, segmentIndex, extractor,
-        extractor.getCues(), nextIndex, evaluation.trigger, numSegmentsPerChunk);
+        dataSource, nextSegmentNum, evaluation.trigger);
     lastChunkWasInitialization = false;
     out.chunk = nextMediaChunk;
   }
@@ -179,53 +181,38 @@ public class DashWebmChunkSource implements ChunkSource {
     // Do nothing.
   }
 
-  private static Chunk newInitializationChunk(Representation representation,
+  private Chunk newInitializationChunk(RangedUri initializationUri, Representation representation,
       WebmExtractor extractor, DataSource dataSource, int trigger) {
-    DataSpec dataSpec = new DataSpec(representation.uri, 0, representation.indexEnd + 1,
+    DataSpec dataSpec = new DataSpec(initializationUri.getUri(), initializationUri.start,
-        representation.getCacheKey());
+        initializationUri.length, representation.getCacheKey());
-    return new InitializationWebmLoadable(dataSource, dataSpec, trigger, extractor, representation);
+    return new InitializationWebmLoadable(dataSource, dataSpec, trigger, representation.format,
+        extractor);
   }
 
-  private static Chunk newMediaChunk(Representation representation,
+  private Chunk newMediaChunk(Representation representation, DashSegmentIndex segmentIndex,
-      WebmExtractor extractor, DataSource dataSource, SegmentIndex cues, int index,
+      WebmExtractor extractor, DataSource dataSource, int segmentNum, int trigger) {
-      int trigger, int numSegmentsPerChunk) {
+    int lastSegmentNum = segmentIndex.getLastSegmentNum();
-
+    int nextSegmentNum = segmentNum == lastSegmentNum ? -1 : segmentNum + 1;
-    // Computes the segments to included in the next fetch.
+    long startTimeUs = segmentIndex.getTimeUs(segmentNum);
-    int numSegmentsToFetch = Math.min(numSegmentsPerChunk, cues.length - index);
+    long endTimeUs = segmentNum < lastSegmentNum ? segmentIndex.getTimeUs(segmentNum + 1)
-    int lastSegmentInChunk = index + numSegmentsToFetch - 1;
+        : startTimeUs + segmentIndex.getDurationUs(segmentNum);
-    int nextIndex = lastSegmentInChunk == cues.length - 1 ? -1 : lastSegmentInChunk + 1;
+    RangedUri segmentUri = segmentIndex.getSegmentUrl(segmentNum);
-
+    DataSpec dataSpec = new DataSpec(segmentUri.getUri(), segmentUri.start, segmentUri.length,
-    long startTimeUs = cues.timesUs[index];
-
-    // Compute the end time, prefer to use next segment start time if there is a next segment.
-    long endTimeUs = nextIndex == -1 ?
-      cues.timesUs[lastSegmentInChunk] + cues.durationsUs[lastSegmentInChunk] :
-      cues.timesUs[nextIndex];
-
-    long offset = cues.offsets[index];
-
-    // Compute combined segments byte length.
-    long size = 0;
-    for (int i = index; i <= lastSegmentInChunk; i++) {
-      size += cues.sizes[i];
-    }
-
-    DataSpec dataSpec = new DataSpec(representation.uri, offset, size,
         representation.getCacheKey());
     return new WebmMediaChunk(dataSource, dataSpec, representation.format, trigger, extractor,
-        startTimeUs, endTimeUs, nextIndex);
+        startTimeUs, endTimeUs, nextSegmentNum);
   }
 
-  private static class InitializationWebmLoadable extends Chunk {
+  private class InitializationWebmLoadable extends Chunk {
 
-    private final Representation representation;
     private final WebmExtractor extractor;
+    private final Uri uri;
 
     public InitializationWebmLoadable(DataSource dataSource, DataSpec dataSpec, int trigger,
-        WebmExtractor extractor, Representation representation) {
+        Format format, WebmExtractor extractor) {
-      super(dataSource, dataSpec, representation.format, trigger);
+      super(dataSource, dataSpec, format, trigger);
       this.extractor = extractor;
-      this.representation = representation;
+      this.uri = dataSpec.uri;
     }
 
     @Override
@@ -234,22 +221,7 @@ public class DashWebmChunkSource implements ChunkSource {
       if (!extractor.isPrepared()) {
         throw new ParserException("Invalid initialization data");
       }
-      validateCues(extractor.getCues());
+      segmentIndexes.put(format.id, new DashWrappingSegmentIndex(extractor.getCues(), uri, 0));
-    }
-
-    private void validateCues(SegmentIndex cues) {
-      long expectedSizeBytes = representation.indexEnd - representation.indexStart + 1;
-      if (cues.sizeBytes != expectedSizeBytes) {
-        Log.w(TAG, "Cues length mismatch: got " + cues.sizeBytes +
-            " but expected " + expectedSizeBytes);
-      }
-      long expectedContentLength = cues.offsets[cues.length - 1] +
-          cues.sizes[cues.length - 1] + representation.indexEnd + 1;
-      if (representation.contentLength > 0
-          && expectedContentLength != representation.contentLength) {
-        Log.w(TAG, "ContentLength mismatch: got " + expectedContentLength +
-          " but expected " + representation.contentLength);
-      }
     }
 
   }

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

@@ -42,6 +42,8 @@ public final class RangedUri {
   private final Uri baseUri;
   private final String stringUri;
 
+  private int hashCode;
+
   /**
    * Constructs an ranged uri.
    * <p>
@@ -82,4 +84,55 @@ public final class RangedUri {
     return uri;
   }
 
+  /**
+   * Attempts to merge this {@link RangedUri} with another.
+   * <p>
+   * A merge is successful if both instances define the same {@link Uri}, and if one starte the
+   * byte after the other ends, forming a contiguous region with no overlap.
+   * <p>
+   * If {@code other} is null then the merge is considered unsuccessful, and null is returned.
+   *
+   * @param other The {@link RangedUri} to merge.
+   * @return The merged {@link RangedUri} if the merge was successful. Null otherwise.
+   */
+  public RangedUri attemptMerge(RangedUri other) {
+    if (other == null || !getUri().equals(other.getUri())) {
+      return null;
+    } else if (length != -1 && start + length == other.start) {
+      return new RangedUri(baseUri, stringUri, start,
+          other.length == -1 ? -1 : length + other.length);
+    } else if (other.length != -1 && other.start + other.length == start) {
+      return new RangedUri(baseUri, stringUri, other.start,
+          length == -1 ? -1 : other.length + length);
+    } else {
+      return null;
+    }
+  }
+
+  @Override
+  public int hashCode() {
+    if (hashCode == 0) {
+      int result = 17;
+      result = 31 * result + (int) start;
+      result = 31 * result + (int) length;
+      result = 31 * result + getUri().hashCode();
+      hashCode = result;
+    }
+    return hashCode;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) {
+      return true;
+    }
+    if (obj == null || getClass() != obj.getClass()) {
+      return false;
+    }
+    RangedUri other = (RangedUri) obj;
+    return this.start == other.start
+        && this.length == other.length
+        && getUri().equals(other.getUri());
+  }
+
 }

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

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer.dash.mpd;
 
 import com.google.android.exoplayer.chunk.Format;
+import com.google.android.exoplayer.dash.DashSegmentIndex;
 
 import android.net.Uri;
 
@@ -79,6 +80,37 @@ public class Representation {
     this.uri = uri;
   }
 
+  /**
+   * Gets a {@link RangedUri} defining the location of the representation's initialization data.
+   * May be null if no initialization data exists.
+   *
+   * @return A {@link RangedUri} defining the location of the initialization data, or null.
+   */
+  public RangedUri getInitializationUri() {
+    return new RangedUri(uri, null, initializationStart,
+        initializationEnd - initializationStart + 1);
+  }
+
+  /**
+   * Gets a {@link RangedUri} defining the location of the representation's segment index. Null if
+   * the representation provides an index directly.
+   *
+   * @return The location of the segment index, or null.
+   */
+  public RangedUri getIndexUri() {
+    return new RangedUri(uri, null, indexStart, indexEnd - indexStart + 1);
+  }
+
+  /**
+   * Gets a segment index, if the representation is able to provide one directly. Null if the
+   * segment index is defined externally.
+   *
+   * @return The segment index, or null.
+   */
+  public DashSegmentIndex getIndex() {
+    return null;
+  }
+
   /**
    * Generates a cache key for the {@link Representation}, in the format
    * {@code contentId + "." + format.id + "." + revisionId}.