Format Sint32 BPL_GetCurStm (Sint32 nelem, Sint32 * stmtbl)
Input nelem: Number of stream handle table elements (nelem ≤ BPL_STMKEY_MAX)
Output stmtbl: Stream handle table
Function value Branch stream identifier (if negative, there is no corresponding branch stream)
Function Current stream that is being read / retrieved (branch stream identification
Get child and stream handle).
Remarks (a) The stream handle table contains a stream corresponding to each stream key.
The handle is set. 

Format Sint32 BPL_GetNextStm (Sint32 nelem, StmHn * stmtbl)
Input nelem: Number of stream handle table elements (nelem ≤ BPL_STMKEY_MAX)
Output stmbl: stream handle table
Function value Branch stream identifier (if negative, there is no corresponding branch stream)
Function Acquires the branch destination stream (branch stream identifier and stream handle).
Remarks (a) The stream handle table contains a stream corresponding to each stream key.
The handle is set.
(B) The function value is always until the branch destination is selected (BPL_SelectBranch is executed).
It is negative. 

Format StmGrpHn BPL_GetStmGrp (void)
No input
No output
Function value Stream group handle
Function Acquires the handle of the stream group used by the branch playback library.
Remarks (a) Branch playback library opens one stream group during operation.
When stream playback ends, the stream group handle is NULL.