discontinuities: if no CC range in common, align sliding using PROGRA…

…M-DATE-TIME (if available) related to #1172
video-dev · Aug 29, 2017 · ae13d80 · ae13d80
1 parent 44aed40
commit ae13d80
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Showing 2 changed files with 122 additions and 3 deletions.
diff --git a/src/utils/discontinuities.js b/src/utils/discontinuities.js
@@ -73,10 +73,23 @@ export function adjustPts(sliding, details) {
 // as a reference
 export function alignDiscontinuities(lastFrag, lastLevel, details) {
   if (shouldAlignOnDiscontinuities(lastFrag, lastLevel, details)) {
-    logger.log('Adjusting PTS using last level due to CC increase within current level');
     const referenceFrag = findDiscontinuousReferenceFrag(lastLevel.details, details);
     if (referenceFrag) {
+      logger.log('Adjusting PTS using last level due to CC increase within current level');
       adjustPts(referenceFrag.start, details);
+    } else if (lastLevel && lastLevel.details) {
+      // try to align using programDateTime attribute (if available)
+      // if last level sliding is 1000 and its first frag PROGRAM-DATE-TIME is 2017-08-20 1:10:00 AM
+      // and if new details first frag PROGRAM DATE-TIME is 2017-08-20 1:10:08 AM
+      // then we can deduce that playlist B sliding is 1000+8 = 1008s
+      let lastPDT = lastLevel.details.programDateTime;
+      let newPDT = details.programDateTime;
+      // date diff is in ms. frag.start is in seconds
+      let sliding = (newPDT - lastPDT)/1000 + lastLevel.details.fragments[0].start;
+      if (!isNaN(sliding)) {
+        logger.log(`no CC range in common between old and new playlist, adjusting using programDateTime delta, sliding:${sliding}`);
+        adjustPts(sliding,details);
+      }
     }
   }
 }
diff --git a/tests/unit/utils/discontinuities.js b/tests/unit/utils/discontinuities.js
@@ -1,6 +1,6 @@
 const assert = require('assert');
 
-import { shouldAlignOnDiscontinuities, findDiscontinuousReferenceFrag, adjustPts } from '../../../src/utils/discontinuities';
+import { shouldAlignOnDiscontinuities, findDiscontinuousReferenceFrag, adjustPts, alignDiscontinuities } from '../../../src/utils/discontinuities';
 
 const mockReferenceFrag = {
   start: 20,
@@ -40,7 +40,7 @@ const mockFrags = [
 
 
 describe('level-helper', function () {
-  it ('adjusts level fragments using a reference fragment', function () {
+  it ('adjusts level fragments with overlapping CC range using a reference fragment', function () {
     const details = {
       fragments: mockFrags.slice(0),
       PTSKnown: false
@@ -78,6 +78,112 @@ describe('level-helper', function () {
   });
 
 
+it ('adjusts level fragments without overlapping CC range but with programDateTime info', function () {
+
+    const lastFrag = { cc : 0 };
+    const lastLevel = {
+      details : {
+        PTSKnown : true,
+        programDateTime : new Date('2017-08-28 00:00:00'),
+        fragments : [
+          {
+            start: 20,
+            end: 24,
+            startPTS: 20,
+            endPTS: 24,
+            duration: 4,
+            cc: 0,
+          },
+          {
+            start: 24,
+            end: 28,
+            startPTS: 24,
+            endPTS: 28,
+            duration: 4,
+            cc: 1
+          },
+          {
+            start: 28,
+            end: 36,
+            startPTS: 28,
+            endPTS: 36,
+            duration: 8,
+            cc: 1
+          }
+        ]
+      }
+    };
+
+    var details = {
+      fragments: [
+          {
+            start: 0,
+            end: 4,
+            startPTS: 0,
+            endPTS: 4,
+            duration: 4,
+            cc: 2,
+          },
+          {
+            start: 4,
+            end: 8,
+            startPTS: 4,
+            endPTS: 8,
+            duration: 4,
+            cc: 2
+          },
+          {
+            start: 8,
+            end: 16,
+            startPTS: 8,
+            endPTS: 16,
+            duration: 8,
+            cc: 3
+          }
+        ],
+      PTSKnown: false,
+      programDateTime : new Date('2017-08-28 00:00:50'),
+      startCC : 2,
+      endCC : 3
+    };
+
+    var detailsExpected = {
+        fragments : [
+          {
+            start: 70,
+            end: 74,
+            startPTS: 70,
+            endPTS: 74,
+            duration: 4,
+            cc: 2
+          },
+          {
+            start: 74,
+            end: 78,
+            startPTS: 74,
+            endPTS: 78,
+            duration: 4,
+            cc: 2
+          },
+          {
+            start: 78,
+            end: 86,
+            startPTS: 78,
+            endPTS: 86,
+            duration: 8,
+            cc: 3
+          }
+        ],
+      PTSKnown: true,
+      programDateTime : new Date('2017-08-28 00:00:50'),
+      startCC : 2,
+      endCC : 3
+    };
+    alignDiscontinuities(lastFrag,lastLevel,details);
+    assert.deepEqual(detailsExpected,details);
+  });
+
+
   it('finds the first fragment in an array which matches the CC of the first fragment in another array', function () {
     const prevDetails = {
       fragments: [mockReferenceFrag, { cc: 1  }]