Compositor video frame transport should not flatten frames into a
shareable bitmap before crossing an IPC boundary. That conversion loses
the native YUV representation and makes Web-side transport code own the
frame wire format.
Teach VideoFrame to encode its YUV planes into a shared anonymous buffer
with the color space, timing, subsampling, bit depth, and CICP metadata
needed to rebuild the frame on decode. Add YUVData helpers for checked
plane sizing and construction from validated plane bytes so malformed
buffers are rejected before a frame is created.
This is preparatory work required to add IPC between the main and
compositor threads.
DecodedImageFrame now owns decoded bitmap pixels directly, so the
separate ImmutableBitmap wrapper no longer carries useful semantics.
Remove the class and pass decoded image frames or bitmaps at the
boundaries where pixels are actually required.
The Skia image cache now keys off DecodedImageFrame, matching the
display-list commands that paint decoded images. Video frames stay
owned by LibMedia, with the explicit YUV-to-bitmap conversion living
at HTMLVideoElement's decoded-frame entry point for canvas and WebGL
callers.
Decoded video frames should own their planar YUV data and color space
directly. Keeping that storage behind ImmutableBitmap gave a
still-image abstraction media-specific behavior and made calls like
bitmap() potentially allocate and convert a whole video frame.
Move YUV ownership into Media::VideoFrame, where the lifetime naturally
follows media playback, and remove the YUV-backed mode from
ImmutableBitmap. This commit intentionally keeps the visible Web paint
path on ExternalContentSource by converting the current frame back to
an ImmutableBitmap where Web still expects one.
Callers that need pixels now ask the frame to convert explicitly. That
preserves behavior for canvas and bitmap consumers while making the
expensive YUV-to-pixel path visible at the call site instead of
hiding it behind ImmutableBitmap::bitmap().
Video frames are about to be shared between the decoder, the data
provider, the display sink, and Web painting code. Passing them by
value keeps ownership tied to the old bitmap-shaped pipeline and makes
later lifetime changes harder to reason about.
Make VideoFrame ref-counted and return NonnullRefPtr from the decoder
and media queues. This changes ownership only: a VideoFrame still wraps
an ImmutableBitmap at this point, so playback behavior remains
unchanged while later commits can move storage and painting
independently.
This saves us from having our own color conversion code, which was
taking up a fair amount of time in VideoDataProvider. With this change,
we should be able to play high resolution videos without interruptions
on machines where the CPU can keep up with decoding.
In order to make this change, ImmutableBitmap is now able to be
constructed with YUV data instead of an RBG bitmap. It holds onto a
YUVData instance that stores the buffers of image data, since Skia
itself doesn't take ownership of them.
In order to support greater than 8 bits of color depth, we normalize
the 10- or 12-bit color values into a 16-bit range.
