This adds a tree-parsing function that can be called statically from
specific trees' implementations in TreeParser, of which Partition is
the first. This way, all calls to tree parses will take the context
they need to be able to select a tree and probabilities, which will
allow removal of the state dependence in TreeParser on fields from
itself and Parser.
This gets the decoder closer to fully parsing the second frame without
any errors. It will still be unable to output an inter-predicted frame.
The lack of output causes VideoPlayer to crash if it attempts to read
the buffers for frame 1, so it is still limited to the first frame.
The first keyframe of the test video can be decoded with these changes.
Raw memory allocations in the Parser have been replaced with Vector or
Array to avoid memory leaks and OOBs.
These elements were being used in the new tokens implementation, so
support for them in the TreeParser has been added.
Additionally, this uncovered a bug where the nonzero contexts were
being cleared with the wrong size.
The class that was previously named Decoder handled section 6.X.X of
the spec, which actually deals with parsing out the syntax of the data,
not the actual decoding logic which is specified in section 8.X.X.
The new Decoder class will be in charge of owning and running the
Parser, as well as implementing all of the decoding behavior.
Now TreeParser has mostly complete probability calculation
implementations for all currently used syntax elements. Some of these
calculation methods aren't actually finished because they use data
we have yet to parse in the Decoder, but they're close to finished.
This patch brings all of LibVideo up to the east-const style in the
project. Additionally, it applies a few fixes from the reviews in #8170
that referred to older LibVideo code.
The TreeParser requires information about a lot of the decoder's
current state in order to parse syntax tree elements correctly, so
there has to be some communication between the Decoder and the
TreeParser. Previously, the Decoder would copy its state to the
TreeParser when it changed, however, this was a poor choice. Now,
the TreeParser simply has a reference to its owning Decoder, and
accesses its state directly.
