L64105 LSI Logic Corporation, L64105 Datasheet - Page 338

• Manufacturer Part Number: L64105
• Description: Mpeg-2 Audio/video Decoder
• Manufacturer: LSI Logic Corporation

10.3 Decoding Flow Control
10.3.1 Audio Decoder Play Mode
10-6
In the PCM FIFO mode, the host writes decoded PCM audio bytes into
a FIFO through a register in the Host Interface. According to the mode
selected, the outputs of the appropriate decoder and formatter and the
PCM FIFO are steered through the two multiplexers to the DAC and S/P
DIF interfaces.
One of the ACLK inputs is selected by the host and divided into three
clocks according to host divider selection. The two derived BCLKs
convert the parallel inputs to the interfaces to serial outputs. The DAC
BCLK is supplied to the external DAC as a bit clock. The divider also
supplies the DAC clock, A_ACLK, to the output multiplexer. The host
must select the proper divider to match the DAC.
The two output multiplexers can bypass the Audio Decoder entirely and
turn the S/P DIF and CD inputs around to the output pins. This feature
lets the L64105 Decoder share a DAC in the system with a CD decoder.
The first part of this section gives brief descriptions of the following
register bits and fields; Audio Decoder Play Mode, Audio Decoder
Start/Stop, Audio Formatter Play Mode, and Audio Formatter Start/Stop .
The second part describes the procedures you should follow to start and
stop the Audio Decoder properly.
The Audio Decoder Play Mode bits in Register 355
the decoder, set it to normal play, and increase or decrease the play
speed by skipping or repeating samples. The decimation or interpolation
factors are one out of every 16 samples for the MPEG Decoder and one
out of every 8 samples for the Linear PCM Decoder. The mode
selections are:
Audio Decoder Module
0b00 - Pause. The decoder is paused and the last pair of PCM and
S/P DIF samples are repeated, effectively muting the output, until the
play mode is changed. The Audio ES Channel Buffer keeps filling
with new data. The decoder continues to decode and write to the
output buffer until the output buffer overflows and stops the audio
read pointer of the Audio ES Channel Buffer. Since there is no
(page
4-79) pause