Bug 206412 – [MSE] Decode glitches when watching videos on CNN.com

• Status: RESOLVED
• Resolution: FIXED
• Component: New Bugs

[Jer Noble]

[MSE] Decode glitches when watching videos on CNN.com

[Jer Noble]

<rdar://problem/55685630>

[Jer Noble]

Created attachment 388034 [details]
Patch

[Alicia Boya García]

Comment on attachment 388034 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=388034&action=review

Looks good to me.

> Source/WebCore/Modules/mediasource/SourceBuffer.cpp:1680
> +        // When appending media containing P-frames (media whose samples' presentation timestamps

I think you mean B-frames. A movie with only I-frames and P-frames has monotonic presentation timestamps, and usually PTS=DTS.

> Source/WebCore/Modules/mediasource/SourceBuffer.cpp:1691
> +            auto nextDecodedSample = trackBuffer.samples.decodeOrder().findSampleAfterDecodeKey(decodeKey);

nextDecodeSample, nextSampleDTS, nextSampleInDecodeOrder or even just nextSample.

> Source/WebCore/Modules/mediasource/SourceBuffer.cpp:1699
> +            if (nextSyncSample == nextDecodedSample)

The only way this could be true is if nextDecodeSample == end(), but that was checked already above.

[Xabier Rodríguez Calvar]

Comment on attachment 388034 [details]
Patch

Thanks Alicia!

[Jer Noble]

(In reply to Alicia Boya García from comment #3)
> Comment on attachment 388034 [details]
> Patch
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=388034&action=review
> 
> Looks good to me.
> 
> > Source/WebCore/Modules/mediasource/SourceBuffer.cpp:1680
> > +        // When appending media containing P-frames (media whose samples' presentation timestamps
> 
> I think you mean B-frames. A movie with only I-frames and P-frames has
> monotonic presentation timestamps, and usually PTS=DTS.

Whoops, looks like I got that... backwards.
> > Source/WebCore/Modules/mediasource/SourceBuffer.cpp:1691
> > +            auto nextDecodedSample = trackBuffer.samples.decodeOrder().findSampleAfterDecodeKey(decodeKey);
> 
> nextDecodeSample, nextSampleDTS, nextSampleInDecodeOrder or even just
> nextSample.

As you can tell from SampleMap, I don’t mind long, descriptive names, so maybe I’ll go with “nextSampleInDecodeOrder”.

> > Source/WebCore/Modules/mediasource/SourceBuffer.cpp:1699
> > +            if (nextSyncSample == nextDecodedSample)
> 
> The only way this could be true is if nextDecodeSample == end(), but that
> was checked already above.

Good catch!

[Jer Noble]

Created attachment 388053 [details]
Patch for landing

[WebKit Commit Bot]

Comment on attachment 388053 [details]
Patch for landing

Clearing flags on attachment: 388053

Committed r254761: <https://trac.webkit.org/changeset/254761>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.