fix(HLS): Fix HLS seekRange for live streams (shaka-project#5263)

lib/hls/hls_parser.js

@@ -401,6 +401,11 @@ shaka.hls.HlsParser = class {
           mediaSequenceNumber);
       stream.segmentIndex.evict(playlistStartTime);
     }
+    const oldSegment = segments[0];
+    goog.asserts.assert(oldSegment, 'Should have segments!');
+
+    streamInfo.minTimestamp = oldSegment.startTime;
+
     const newestSegment = segments[segments.length - 1];
     goog.asserts.assert(newestSegment, 'Should have segments!');
 
@@ -578,6 +583,9 @@ shaka.hls.HlsParser = class {
    * @private
    */
   offsetStreamInfo_(streamInfo, offset) {
+    // Adjust our accounting of the minimum timestamp.
+    streamInfo.minTimestamp += offset;
+
     // Adjust our accounting of the maximum timestamp.
     streamInfo.maxTimestamp += offset;
     goog.asserts.assert(streamInfo.maxTimestamp >= 0,
@@ -1068,7 +1076,7 @@ shaka.hls.HlsParser = class {
       const PresentationType = shaka.hls.HlsParser.PresentationType_;
 
       if (this.presentationType_ == PresentationType.LIVE) {
-        let segmentAvailabilityDuration = this.getMinDuration_();
+        let segmentAvailabilityDuration = this.getLiveDuration_();
 
         // This defaults to the presentation delay, which has the effect of
         // making the live stream unseekable.  This is consistent with Apple's
@@ -1927,6 +1935,7 @@ shaka.hls.HlsParser = class {
       verbatimMediaPlaylistUri,
       // These values are filled out or updated after lazy-loading:
       absoluteMediaPlaylistUri: initialMediaPlaylistUri,
+      minTimestamp: 0,
       maxTimestamp: 0,
       mediaSequenceToStartTime: new Map(),
       canSkipSegments: false,
@@ -1972,6 +1981,7 @@ shaka.hls.HlsParser = class {
 
       // Copy values from the real stream info to our initial one.
       streamInfo.absoluteMediaPlaylistUri = absoluteMediaPlaylistUri;
+      streamInfo.minTimestamp = realStreamInfo.minTimestamp;
       streamInfo.maxTimestamp = realStreamInfo.maxTimestamp;
       streamInfo.canSkipSegments = realStreamInfo.canSkipSegments;
       streamInfo.hasEndList = realStreamInfo.hasEndList;
@@ -2098,6 +2108,22 @@ shaka.hls.HlsParser = class {
     return minDuration;
   }
 
+  /**
+   * @return {number}
+   * @private
+   */
+  getLiveDuration_() {
+    let maxTimestamp = Infinity;
+    let minTimestamp = Infinity;
+    for (const streamInfo of this.uriToStreamInfosMap_.values()) {
+      if (streamInfo.stream.segmentIndex && streamInfo.stream.type != 'text') {
+        maxTimestamp = Math.min(maxTimestamp, streamInfo.maxTimestamp);
+        minTimestamp = Math.min(minTimestamp, streamInfo.minTimestamp);
+      }
+    }
+    return maxTimestamp - minTimestamp;
+  }
+
   /**
    * @param {!Array.<!shaka.extern.Stream>} streams
    * @private
@@ -2236,6 +2262,7 @@ shaka.hls.HlsParser = class {
       this.determinePresentationType_(playlist);
     }
 
+    const firstStartTime = segments[0].startTime;
     const lastEndTime = segments[segments.length - 1].endTime;
     /** @type {!shaka.media.SegmentIndex} */
     const segmentIndex = new shaka.media.SegmentIndex(segments);
@@ -2258,6 +2285,7 @@ shaka.hls.HlsParser = class {
       type,
       verbatimMediaPlaylistUri,
       absoluteMediaPlaylistUri,
+      minTimestamp: firstStartTime,
       maxTimestamp: lastEndTime,
       canSkipSegments,
       hasEndList: false,
@@ -3569,6 +3597,7 @@ shaka.hls.HlsParser = class {
  *   type: string,
  *   verbatimMediaPlaylistUri: string,
  *   absoluteMediaPlaylistUri: string,
+ *   minTimestamp: number,
  *   maxTimestamp: number,
  *   mediaSequenceToStartTime: !Map.<number, number>,
  *   canSkipSegments: boolean,
@@ -3592,6 +3621,8 @@ shaka.hls.HlsParser = class {
  * @property {string} absoluteMediaPlaylistUri
  *   The absolute media playlist URI, resolved relative to the master playlist
  *   and updated to reflect any redirects.
+ * @property {number} minTimestamp
+ *   The minimum timestamp found in the stream.
  * @property {number} maxTimestamp
  *   The maximum timestamp found in the stream.
  * @property {!Map.<number, number>} mediaSequenceToStartTime