tree 1e9f7e78eea210064c19a0a19d806448bd81ed1f
parent e5205a33ad940dafdb4fab5d7ea875f3f7a241c2
author jer.noble@apple.com <jer.noble@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1579295035 +0000
committer jer.noble@apple.com <jer.noble@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1579295035 +0000

[MSE] Decode glitches when watching videos on CNN.com
https://bugs.webkit.org/show_bug.cgi?id=206412
<rdar://problem/55685630>

Reviewed by Xabier Rodriguez-Calvar.

Source/WebCore:

Test: media/media-source/media-source-samples-out-of-order.html

The "Coded frame processing" algorithm has a known shortcoming <https://github.com/w3c/media-source/issues/187>
when dealing appends of with "SAP Type 2" content, or in general terms, appending data where the resulting samples
have presentation times that do not increase monotonically. When this occurs, the ordering of samples in presentation
time will be different from the ordering of samples in decode time. The decoder requires samples to be enqueued in
decode time order, but the MSE specification only checks for overlapping samples in presentation time order. During
appends of out-of-order samples, this can lead to new samples being inserted between a previously appended sample and
the sample on which that sample depends.

To resolve this, add a new step in the implementation of the "coded frame processing" algorithm in
SourceBuffer::sourceBufferPrivateDidReceiveSample(). When the incoming frame is a sync sample, search forward
in the TrackBuffer for all previous samples in between the new sync sample, and the next sync sample. All the
samples found in this step would fail to decode correctly if enqueued after the new (possibly different resolution)
sync sample, so they are removed in this step.

* Modules/mediasource/SampleMap.cpp:
(WebCore::DecodeOrderSampleMap::findSampleAfterDecodeKey):
* Modules/mediasource/SampleMap.h:
* Modules/mediasource/SourceBuffer.cpp:
(WebCore::SourceBuffer::sourceBufferPrivateDidReceiveSample):

LayoutTests:

* media/media-source/media-source-samples-out-of-order-expected.txt: Added.
* media/media-source/media-source-samples-out-of-order.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@254761 268f45cc-cd09-0410-ab3c-d52691b4dbfc