Normal Play Sequence
9-5
The channel start and end addresses dene the location and
size of the SPU Channel Buffer in SDRAM. The Channel Reset
bit sets the write pointer of the SPU Channel Buffer to the
Channel Start Address. The SPU Stream Select Enable must
be set to decode SPU streams, and the SPU Substream ID for
the stream to be parsed and decoded must be entered in the
SPU Substream ID eld in Register 146.
The Video Interface uses the Chroma Filter to enhance the
edge conditions of the SPU. It detects the SPU edge, averages
the two pixels adjacent to the edge, and adjusts the mix weights
of the SPU edge pixels.
The SPU Mix Enable bit must be set for the Video Interface to
mix the subpicture with the main display. The palette can be
lled from the bitstream or by the host on a unit-by-unit basis.
If the palette information is to be taken from the bitstream, the
Reset Autoll Counter bit must be initialized to the beginning
address of the palette table.
When the Frame-Based Execution bit is set, Time-Stamp
analysis is performed only at the beginning of odd elds. When
the bit is cleared, the analysis is performed at the beginning of
every eld. The Command Time-Out value is a host-controlled
Step 2.
Start the Channel Interface.
The host sets the Channel Start/Reset bit to read all bitstream
bytes into the Channel Interface for preparsing and storage in
the channel buffers.
Step 3.
Wait for the rst pack header, extract the System Clock
Reference (SCR), and load it into the SCR counter.
The Channel Interface Preparser does this automatically when
it detects the rst pack header after channel start. This is done
to update the SCR counter at the start of a program.
Step 4.
Wait for the rst Navi pack and initialize the palette table with
color information in the packet.
The rst SPU pack should be a Navi pack with color information
in its PCI packet. If the palette needs to be changed between
SPUs, a Navi pack is inserted between them in the bitstream.
Unless the host intervenes, the address pointer for the palette
table should wrap around to the start address each time the
palette table is lled so it is ready for the next rell.