Bug 170325 – captureStream is getting black frames with webgl canvas

• Component: WebCore Misc.
• Status: RESOLVED FIXED

[youenn fablet]

captureStream is getting black frames with webgl canvas

[youenn fablet]

Created attachment 305941 [details]
Patch

[youenn fablet]

(In reply to youenn fablet from comment #0)
> captureStream is getting black frames with webgl canvas

Regression is due to the timer introduced to not produce too many frames.

[youenn fablet]

Created attachment 305979 [details]
Fixing release builds

[Dean Jackson]

Comment on attachment 305979 [details]
Fixing release builds

View in context: https://bugs.webkit.org/attachment.cgi?id=305979&action=review

> Source/WebCore/Modules/mediastream/CanvasCaptureMediaStreamTrack.cpp:136
> +    if (canvas.renderingContext() && canvas.renderingContext()->isWebGL())
> +        static_cast<WebGLRenderingContextBase*>(canvas.renderingContext())->preserveDrawingBuffer();

Doing this does have a negative performance effect on the WebGL context. Maybe until we have the recording synced with the endPaint, we should print a warning to the console saying this might be slow (if the context wasn't already created with preserveDrawingBuffer = true)

> Source/WebCore/html/canvas/WebGLRenderingContextBase.h:210
> +    void preserveDrawingBuffer() { m_attributes.preserveDrawingBuffer = true; }

I think this should be setPreserveDrawingBuffer(bool), with a preserveDrawingBuffer() getter.

> Source/WebCore/testing/Internals.h:590
> +    std::optional<TrackFramePromise> m_nextFramePromise;

Maybe m_nextTrackFramePromise?

[youenn fablet]

Created attachment 306023 [details]
Updated according review

[youenn fablet]

(In reply to Dean Jackson from comment #4)
> Comment on attachment 305979 [details]
> Fixing release builds
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=305979&action=review
> 
> > Source/WebCore/Modules/mediastream/CanvasCaptureMediaStreamTrack.cpp:136
> > +    if (canvas.renderingContext() && canvas.renderingContext()->isWebGL())
> > +        static_cast<WebGLRenderingContextBase*>(canvas.renderingContext())->preserveDrawingBuffer();
> 
> Doing this does have a negative performance effect on the WebGL context.
> Maybe until we have the recording synced with the endPaint, we should print
> a warning to the console saying this might be slow (if the context wasn't
> already created with preserveDrawingBuffer = true)

Added

> 
> > Source/WebCore/html/canvas/WebGLRenderingContextBase.h:210
> > +    void preserveDrawingBuffer() { m_attributes.preserveDrawingBuffer = true; }
> 
> I think this should be setPreserveDrawingBuffer(bool), with a
> preserveDrawingBuffer() getter.

OK

> > Source/WebCore/testing/Internals.h:590
> > +    std::optional<TrackFramePromise> m_nextFramePromise;
> 
> Maybe m_nextTrackFramePromise?

OK

[youenn fablet]

Created attachment 306076 [details]
Patch for landing

[youenn fablet]

Thanks for the review.

> Doing this does have a negative performance effect on the WebGL context.
> Maybe until we have the recording synced with the endPaint, we should print
> a warning to the console saying this might be slow (if the context wasn't
> already created with preserveDrawingBuffer = true)

I added the log message and added a test to cover "preserveDrawingBuffer = true" case.

[WebKit Commit Bot]

Comment on attachment 306076 [details]
Patch for landing

Clearing flags on attachment: 306076

Committed r214806: <http://trac.webkit.org/changeset/214806>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.