ZR38600/38601 audio serial input interface - HELP !

Hi, we designed a mpeg-dvd video decoder. Then we connect the video
decoder with ZORAN 38600 or 38601 with serial data input. But we do
not have good result from this connection. Some of 'AC3 frame in
32msec' of the AC3 stream data can be decoded successfully but all
others are not. When we use parallel data input the AC3 data could be
decoded successfully. We think that the serial data input interface of
our chip may have some mistakes.

Our interface settings are:

- Stream data input (the AC3 elementary) via SCKA/FSA/SDA/DREQ
- Frame sync mode
- Slave in Zoran (SCKA clock input)
- SCKA Frequency = 27/4(6.75) MHz
- Handshake with the dreq signal
- If the dreq is asserted at the start of frame, the 16 bits
data stream is transferred to Zoran. And even if the dreq
in negated in the middle of this 16 bits transfer, 16-bit
data transfer is not stopped.
- The audio stream data buffer in DRAM is big, so the audio
data can be sent to Zoran by the dreq anytime. (It can
transfer over 2 AC3 frame data in one AC3 frame data time.)

Could you please give me any comments for the connection?

thanks in advance,

* Kiyoshi Takagi @ New Japan Radio Company Ltd