
1-6
Introduction
Hardware error handling includes error masking and the application of
concealment vectors in video. Audio error concealment includes muting
on errors and searching for error-free frames. The channel interface ags
gross errors in the bitstream that are due to channel buffer overrun or
underrun or to nonconformance in the bitstream. Error agging enables
the masking of errors in the display or in the audio output.
The L64021 channel interface also includes a fully integrated CSS
module that provides disc/title key authentication and A/V descrambling.
The CSS module operates in one of ve modes: bypass, data key
extraction, A/V descramble, disc key authentication and extraction, or title
key authentication and decryption.
1.2.5 Memory Interface
The L64021 directly connects to commercial SDRAMs for use as frame
stores, channel buffers, and OSD memory. The L64021 uses frame
stores to store reconstructed pictures until they are displayed. It
constructs separate video and audio channel buffers to temporarily store
incoming audio, video, and header data. Some regions of memory can
be used for graphic overlay. This storage is combined into a single,
contiguous memory space accessed over a 16-bit wide bus. In most
cases, this is one 1 M x 16-bit SDRAM, for a total memory space of
2 Mbytes. A second1Mx 16-bit SDRAM device can be added for a total
memory space of 4 Mbytes.
The interface between the L64021 and SDRAM requires no external
components. The L64021 pinout allows connection to the SDRAM to be
made on a single PCB layer. During normal operation, the L64021
exclusively controls the SDRAM frame stores. However, it is possible to
access the SDRAM through the host port on the L64021 for testing and
verication, for storing OSD information, and for accessing the frame
stores and channel information.