Problem when I use SBE to read live DVRMS file??

[Eric]

Dears,

I met a strange problem when I use SBE source filter to streaming DVR-MS
file on Vista.
Here is the situation.
I record a TV program by MCE then using SBE source filter to read the
recording file.
But I will receive EOS notify from SBE source fitler and the streaming will
stop.
I used IStreamBufferMediaSeeking interface to query sbe source filter's
status.
I found a strange behavior.
The value from function
GetAvailable
GetPositions
can let me got the current position and the end position of sbe source
filter.

I can know the currect read position & end position.
but I will receive eos in some abnormal situation.
ex:
end position is 8 seconds, but I receive eos when current position is 2
seconds.
the gap between end and current position is different among different
platform.
In some platform, the gap would be 6 seconds(ex: current 2 seconds, end: 8
seconds. Received eos if the gap small than 6 seconds. i,e. current 3
seconds, end: 8 seconds), but in other platform the gap will become 4
seconds. (ex: current 4 seconds, end: 8 seconds).

Currently I can only work around this issue by keep enough gap for
streaming.

Does anyone know what happened? Is there any stable way can let me predict
the real gap of specified platform?
Any idea would be appricated...

Thank you~~

Eric