Changeset 237657 in webkit

Timestamp:

Oct 31, 2018 3:05:51 PM (5 years ago)

Author:

aboya@igalia.com

Message:

[MSE] Use tolerance when growing the coded frame group
​https://bugs.webkit.org/show_bug.cgi?id=190085

Reviewed by Jer Noble.

Source/WebCore:

Test: media/media-source/media-source-append-acb-tolerance.html

This patch introduces a millisecond tolerance in the range of
potential frames that should be erased frame from the track buffer
when the coded frame group is growing.

This is necessary because some files have imprecise overlapping
timestamps (especially WebM files).

This fixes a stall when seeking back and forth in YouTube with WebM
video.

A test case simulating the problem with video/mock using timestamps
similar to those of a typical 30 fps WebM video is also added.

• Modules/mediasource/SourceBuffer.cpp:

(WebCore::SourceBuffer::sourceBufferPrivateDidReceiveSample):

LayoutTests:

A test simulating unordered appends with imprecise timestamps,
overlapping <1ms (replicating a typical WebM 30fps video file) is
added.

• media/media-source/media-source-append-acb-tolerance.html: Added.

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/media/media-source/media-source-append-acb-tolerance-expected.txt (added)
• LayoutTests/media/media-source/media-source-append-acb-tolerance.html (added)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/Modules/mediasource/SourceBuffer.cpp (modified) (3 diffs)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2018-10-31  Alicia Boya García  <aboya@igalia.com>
+
+        [MSE] Use tolerance when growing the coded frame group
+        https://bugs.webkit.org/show_bug.cgi?id=190085
+
+        Reviewed by Jer Noble.
+
+        A test simulating unordered appends with imprecise timestamps,
+        overlapping <1ms (replicating a typical WebM 30fps video file) is
+        added.
+
+        * media/media-source/media-source-append-acb-tolerance.html: Added.
+
 2018-10-31  Devin Rousso  <drousso@apple.com>
 

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2018-10-31  Alicia Boya García  <aboya@igalia.com>
+
+        [MSE] Use tolerance when growing the coded frame group
+        https://bugs.webkit.org/show_bug.cgi?id=190085
+
+        Reviewed by Jer Noble.
+
+        Test: media/media-source/media-source-append-acb-tolerance.html
+
+        This patch introduces a millisecond tolerance in the range of
+        potential frames that should be erased frame from the track buffer
+        when the coded frame group is growing.
+
+        This is necessary because some files have imprecise overlapping
+        timestamps (especially WebM files).
+
+        This fixes a stall when seeking back and forth in YouTube with WebM
+        video.
+
+        A test case simulating the problem with video/mock using timestamps
+        similar to those of a typical 30 fps WebM video is also added.
+
+        * Modules/mediasource/SourceBuffer.cpp:
+        (WebCore::SourceBuffer::sourceBufferPrivateDidReceiveSample):
+
 2018-10-31  Jer Noble  <jer.noble@apple.com>
 

trunk/Source/WebCore/Modules/mediasource/SourceBuffer.cpp

@@ -1646 +1646 @@
         }
 
+        // There are many files out there where the frame times are not perfectly contiguous and may have small overlaps
+        // between the beginning of a frame and the end of the previous one; therefore a tolerance is needed whenever
+        // durations are considered.
+        // For instance, most WebM files are muxed rounded to the millisecond (the default TimecodeScale of the format)
+        // but their durations use a finer timescale (causing a sub-millisecond overlap). More rarely, there are also
+        // MP4 files with slightly off tfdt boxes, presenting a similar problem at the beginning of each fragment.
+        const MediaTime contiguousFrameTolerance = MediaTime(1, 1000);
+
         // If highest presentation timestamp for track buffer is set and less than or equal to presentation timestamp
         if (trackBuffer.highestPresentationTimestamp.isValid() && trackBuffer.highestPresentationTimestamp <= presentationTimestamp) {
@@ -1659 +1667 @@
 
                 MediaTime highestBufferedTime = trackBuffer.buffered.maximumBufferedTime();
+                MediaTime eraseBeginTime = trackBuffer.highestPresentationTimestamp;
+                MediaTime eraseEndTime = frameEndTimestamp - contiguousFrameTolerance;
 
                 PresentationOrderSampleMap::iterator_range range;
                 if (highestBufferedTime - trackBuffer.highestPresentationTimestamp < trackBuffer.lastFrameDuration)
                     // If the new frame is at the end of the buffered ranges, perform a sequential scan from end (O(1)).
-                    range = trackBuffer.samples.presentationOrder().findSamplesBetweenPresentationTimesFromEnd(trackBuffer.highestPresentationTimestamp, frameEndTimestamp);
+                    range = trackBuffer.samples.presentationOrder().findSamplesBetweenPresentationTimesFromEnd(eraseBeginTime, eraseEndTime);
                 else
                     // In any other case, perform a binary search (O(log(n)).
-                    range = trackBuffer.samples.presentationOrder().findSamplesBetweenPresentationTimes(trackBuffer.highestPresentationTimestamp, frameEndTimestamp);
+                    range = trackBuffer.samples.presentationOrder().findSamplesBetweenPresentationTimes(eraseBeginTime, eraseEndTime);
 
                 if (range.first != trackBuffer.samples.presentationOrder().end())
@@ -1727 +1737 @@
         // In order to check whether a frame should be added to the decode queue we check whether it starts after the
         // lastEnqueuedDecodeEndTime or even a bit before that to accomodate files with imprecise timing information.
-        //
-        // There are many files out there where the frame times are not perfectly contiguous, therefore a tolerance is needed.
-        // For instance, most WebM files are muxed rounded to the millisecond (the default TimecodeScale of the format).
-        const MediaTime contiguousFrameTolerance = MediaTime(1, 1000);
         if (trackBuffer.lastEnqueuedDecodeEndTime.isInvalid() || decodeTimestamp >= (trackBuffer.lastEnqueuedDecodeEndTime - contiguousFrameTolerance)) {
             DecodeOrderSampleMap::KeyType decodeKey(sample.decodeTime(), sample.presentationTime());