2/24/2008 9T6WP
Preliminary Hardware Data Module
BCM7405
06/29/07
Functional Description
Bro a d c o m Co rp o r a ti o n
Document
7405-1HDM00-R
Data Transport Processor Page 1-15
Table 1-3: Definition of Terms
Term
Definition
Input Band
Refers to the six external transport stream inputs supported by this design (IB0-5).
Parser Band
Refers to the transport streams that are selected as inputs to the six front end parsers or five
playback channels to five playback parsers.
Playback Channel
Refers to the stream that the playback circuit is reading out of memory. A playback channel is
essentially another possible input band when the stream is a transport stream. A playback channel
could also be called a playback band, but is referred to as a playback channel in this document.
PID Channel
The job of each parser is to map the transport packets of the selected parser band to 0 or more PID
channels (of which there are 255 available).
DMA Channel
Used for the PID Channels that have an associated DMA message buffer. All DMA Channels have
an associated PID Channel.
Record Channel
Refers to the stream that has been selected for recording. This stream can be made up of one or
more PID channels selected directly from the Input Buffer output stream, the downstream
descrambler output stream, and optionally the playback channels.
AV Channel
This term refers to a PID channel selected for parsing by Audio and Video decoders.
Linked-Lists
The playback and record functions (including SCD) utilize a linked-list of descriptors to define the
location(s) of the buffers used by the playback and record functions. A descriptor is simply a set of
four 32-bit words that provides the information required to define a buffer size and location. Because
each descriptor also contains a field that is the address of the next descriptor, the descriptors are
said to be linked and this creates a linked-list of descriptors.
RAVE
Record, Audio, Video interface Engine is a programmable module and in addition to the audio/video
parser functions, RAVE supports record functionality for PVR applications.