[Webkit-unassigned] [Bug 225800] [MSE] MediaSample that need to be removed with SourceBufferPrivate::evictCodedFrames() may not be removed.

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=225800

Jer Noble <jer.noble at apple.com> changed:

           What    |Removed                     |Added
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 Attachment #428607|review?                     |review-
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--- Comment #6 from Jer Noble <jer.noble at apple.com> ---
Comment on attachment 428607
  --> https://bugs.webkit.org/attachment.cgi?id=428607
patch

> >Comparing `rangeEnd` to `mininimumRangeStart` feels wrong here. 
> 
> I think it is correct to compare with rangeEnd.

No, it's definitely not. You can see why it's wrong here:

-            rangeEnd = buffered.start(endTimeRange);
+            if (endTimeRange == notFound)
+                rangeStart = buffered.end(startTimeRange);
+            else
+                rangeEnd = buffered.start(endTimeRange);

If that comparison was correct, this change would be unnecessary. This just adds a complicated calculation to an already overcomplicated while loop.

The correct fix would look more like this:

@@ -689,7 +689,7 @@ void SourceBufferPrivate::evictCodedFrames(uint64_t newDataSize, uint64_t pendin
         return;
     }

-    MediaTime minimumRangeStart = currentTime + thirtySeconds;
+    MediaTime minimumRangeStart = std::min(currentTime + thirtySeconds, buffered.end(currentTimeRange));

     rangeEnd = duration;
     if (!rangeEnd.isFinite()) {

This sets up minimumRangeStart correctly to be located at the end of the current range, or 30s after currentTime, whichever is lower.

@@ -701,16 +701,6 @@ void SourceBufferPrivate::evictCodedFrames(uint64_t newDataSize, uint64_t pendin

     rangeStart = rangeEnd - thirtySeconds;
     while (rangeStart > minimumRangeStart) {
-        // Do not evict data from the time range that contains currentTime.
-        uint64_t startTimeRange = buffered.find(rangeStart);
-        if (currentTimeRange != notFound && startTimeRange == currentTimeRange) {
-            uint64_t endTimeRange = buffered.find(rangeEnd);
-            if (currentTimeRange != notFound && endTimeRange == currentTimeRange)
-                break;
-
-            rangeEnd = buffered.start(endTimeRange);
-        }
-

And now we don't need to do a complicated recalculation at every step through the loop. It just walks back in 30s increments until it reaches minimumRangeStart.

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