onset.f,v

lpc10-15为美军2400bps语音压缩标准的C语音源代码。

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1.5
date	96.03.15.16.41.01;	author jaf;	state Exp;
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1.4
date	96.03.15.15.48.27;	author jaf;	state Exp;
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1.3
date	96.03.14.23.53.06;	author jaf;	state Exp;
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1.2
date	96.03.12.23.53.00;	author jaf;	state Exp;
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1.1
date	96.02.07.14.48.09;	author jaf;	state Exp;
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desc
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1.5
log
@Just rearranged INITONSET assignment orders to be consistent with
order of DATA statements in ONSET.
@
text
@*******************************************************************
*
*	ONSET Version 49
*
* $Log: onset.f,v $
* Revision 1.4  1996/03/15  15:48:27  jaf
* Changed some comments, and only reordered the DATA statements (their
* meaning wasn't changed).
*
* Revision 1.3  1996/03/14  23:53:06  jaf
* Added an entry INITONSET that reinitializes the local state variables
* of subroutine ONSET.
*
* Rearranged quite a few comments, adding more explaining which
* arguments were inputs, and how the modified ones can be changed.
*
* Revision 1.2  1996/03/12  23:53:00  jaf
* Lots of comments added about the local state of this subroutine that
* must be saved from one invocation to the next.
*
* One constant 180 replaced with LFRAME, which should be "more general",
* even though it would probably require many more changes than this to
* get this coder to work for other frame sizes.
*
* Revision 1.1  1996/02/07 14:48:09  jaf
* Initial revision
*
*
*******************************************************************
*
*	Floating point version
*
*
*   Detection of onsets in (or slightly preceding) the futuremost frame
*   of speech.
*
*
* Input:
*  PEBUF(SBUFL:SBUFH)  - Preemphasized speech
*                        Indices SBUFH-LFRAME through SBUFH are read.
*  OSLEN  - Maximum number of onsets that can be stored in OSBUF.
*  SBUFL, SBUFH        - Range of PEBUF
*  LFRAME              - length of a frame, in samples
* Input/Output:
*  OSBUF(OSLEN) - Buffer which holds sorted indexes of onsets
*                 Indices A through B are modified, where A
*                 is the original value of OSPTR, and B is the final
*                 value of OSPTR-1.  B is at most OSLEN.
*  OSPTR        - Free pointer into OSBUF
*                 Initial value should be .LE. OSLEN+1.
*                 If so, final value grows by one for each new onset
*                 found, and final value will be .LE. OSLEN+1.
* 
* This subroutine maintains local state from one call to the next.  If
* you want to switch to using a new audio stream for this subroutine, or
* reinitialize its state for any other reason, call the ENTRY INITONSET.
*

	SUBROUTINE ONSET( PEBUF, OSBUF, OSPTR, OSLEN,
     1                   SBUFL, SBUFH, LFRAME )
	INCLUDE 'config.fh'

*       Arguments

	INTEGER OSLEN, SBUFL, SBUFH, LFRAME
	REAL PEBUF(SBUFL:SBUFH)
	INTEGER OSBUF(OSLEN), OSPTR

*       Parameters/constants

*   Parameters for onset detection algorithm:
*    L2		Threshold for filtered slope of FPC (function of L2WID!)
*    L2LAG	Lag due to both filters which compute filtered slope of FPC
*    L2WID	Width of the filter which computes the slope of FPC
*    OSHYST	The number of samples of slope(FPC) which must be below
*	        the threshold before a new onset may be declared.

	INTEGER L2LAG, L2WID, OSHYST, TEMP
	REAL L2
	PARAMETER (L2=1.7, L2LAG=9, L2WID=16, OSHYST=10)
	PARAMETER (TEMP=1+L2WID/2)

*       Local variables that need not be saved

	INTEGER I
	REAL L2SUM2

*       Local state

*   Variables
*    N, D       Numerator and denominator of prediction filters
*    FPC        Current prediction coefs
*    L2BUF, L2SUM1, L2SUM2    State of slope filter

*       The only "significant" change I've made is to change L2SUM2 out
*       of the list of local variables that need to be saved, since it
*       didn't need to be.

*       L2SUM1 need not be, but avoiding saving it would require a small
*       change to the body of the code.  See comments below for an
*       example of how the code could be changed to avoid saving L2SUM1.

*       FPC and LASTI are saved from one invocation to the next, but
*       they are not given initial values.  This is acceptable, because
*       FPC will be assigned a value the first time that this function
*       is called after D is initialized to 1, since the formula to
*       change D will not change it to 0 in one step, and the IF (D
*       .NE. 0) statement will execute its THEN part, initializing FPC.
*       
*       LASTI's value will not be used until HYST is .TRUE., and
*       whenever HYST is changed from its initial value of .FALSE.,
*       LASTI is assigned a value.

*       In a C version of this coder, it would be nice if all of these
*       saved things, in this and all other subroutines, could be stored
*       in a single struct lpc10_coder_state_t, initialized with a call
*       to a function like lpc10_init(&lpc10_coder_state).  In this way,
*       a program that used these functions could conveniently alternate
*       coding more than one distinct audio stream.

	REAL N, D, FPC
	REAL L2BUF(L2WID), L2SUM1
	INTEGER L2PTR1, L2PTR2, LASTI
	LOGICAL HYST

	DATA N/0./, D/1./
	DATA L2BUF/L2WID*0./, L2SUM1/0./
	DATA L2PTR1/1/, L2PTR2/TEMP/
	DATA HYST/.FALSE./

	SAVE N, D, FPC
	SAVE L2BUF, L2SUM1
	SAVE L2PTR1, L2PTR2, LASTI
	SAVE HYST

*       The following line subtracted a hard-coded "180" from LASTI,
*       instead of using a variable like LFRAME or a constant like
*       MAXFRM.  I changed it to LFRAME, for "generality".

	IF (HYST) LASTI = LASTI - LFRAME
	DO I = SBUFH-LFRAME+1, SBUFH

*   Compute FPC; Use old FPC on divide by zero; Clamp FPC to +/- 1.
	   N=(PEBUF(I)*PEBUF(I-1)+63.*N) / 64.
	   D=(PEBUF(I-1)**2+63.*D) / 64.
	   IF (D .NE. 0.) THEN
	      IF (ABS(N) .GT. D) THEN
	         FPC = SIGN (1., N)
	      ELSE
	         FPC=N/D
	      END IF
	   END IF
*   Filter FPC

*       In order to allow L2SUM1 not to be saved from one invocation of
*       this subroutine to the next, one could change the sequence of
*       assignments below, up to the IF statement, to the following.  In
*       addition, the initial value of L2PTR2 should be changed to
*       L2WID/2 instead of L2WID/2+1.
*       
*       L2SUM1 = L2BUF(L2PTR2)
*       L2PTR2 = MOD(L2PTR2,L2WID)+1
*       L2SUM1 = L2SUM1 - L2BUF(L2PTR2) + FPC
*       L2BUF(L2PTR2) = L2SUM1
*       
**       The following lines didn't change from the original:
*       L2SUM2 = L2BUF(L2PTR1)
*       L2BUF(L2PTR1) = FPC
*       L2PTR1 = MOD(L2PTR1,L2WID)+1
*       

	   L2SUM2 = L2BUF(L2PTR1)
	   L2SUM1 = L2SUM1 - L2BUF(L2PTR2) + FPC
	   L2BUF(L2PTR2) = L2SUM1
	   L2BUF(L2PTR1) = FPC
	   L2PTR1 = MOD(L2PTR1,L2WID)+1
	   L2PTR2 = MOD(L2PTR2,L2WID)+1
	   IF (ABS(L2SUM1-L2SUM2) .GT. L2) THEN
	      IF (.NOT. HYST) THEN
*   Ignore if buffer full
	         IF (OSPTR .LE. OSLEN) THEN
	            OSBUF (OSPTR) = I - L2LAG
	            OSPTR = OSPTR + 1
	         END IF
	         HYST = .TRUE.
	      END IF
	      LASTI = I

*       After one onset detection, at least OSHYST sample times must go
*       by before another is allowed to occur.

	   ELSE IF (HYST .AND. I - LASTI .GE. OSHYST) THEN
	      HYST = .FALSE.
	   END IF
	END DO
	RETURN


	ENTRY INITONSET ()

	N = 0.
	D = 1.
	DO I = 1, L2WID
	   L2BUF(I) = 0.
	END DO
	L2SUM1 = 0.
	L2PTR1 = 1
	L2PTR2 = TEMP
	HYST = .FALSE.

	RETURN

	END
@


1.4
log
@Changed some comments, and only reordered the DATA statements (their
meaning wasn't changed).
@
text
@d6 4
d201 2
d206 1
a208 1
	L2SUM1 = 0.
a209 2
	N = 0.
	D = 1.
@


1.3
log
@Added an entry INITONSET that reinitializes the local state variables
of subroutine ONSET.

Rearranged quite a few comments, adding more explaining which
arguments were inputs, and how the modified ones can be changed.
@
text
@d6 7
d34 1
a34 1
* Inputs:
d65 2
d84 2
d91 2
a92 2
*       The only "significant" change I've made is to remove L2SUM2 from
*       the list of local variables that need to be saved, since it
d99 11
d111 5
a115 5
*       saved things could be initialized with a call to a function like
*       lpc_init(&lpc_coder_state), where lpc_coder_state is a structure
*       containing all of these variables.  In this way, a program that
*       used these functions could conveniently use these functions to
*       alternate coding more than one distinct audio stream.
d122 3
a124 2
	DATA L2BUF/L2WID*0./, L2PTR1/1/, L2PTR2/TEMP/
	DATA L2SUM1/0./
a125 1
	DATA N/0./, D/1./
d152 4
a155 13
*       this subroutine to the next, one could change the assignment to
*       it below to the following, where PRPTR2 is intended to mean
*       "previous L2PTR2, i.e., the value of L2PTR2 before it was
*       modified last time":
*       
*       PRPTR2 = L2PTR2 - 1
*       IF (PRPTR2 .EQ. 0) PRPTR2 = L2WID
*       L2SUM1 = L2BUF(PRPTR2) - L2BUF(L2PTR2) + FPC
*       
*       Another possibility is to leave L2PTR2 unincremented until the
*       "next call", by replacing all of the lines up to the IF
*       statement below with the following (in addition to initializing
*       L2PTR2 to one less than its current initial value).
@


1.2
log
@Lots of comments added about the local state of this subroutine that
must be saved from one invocation to the next.

One constant 180 replaced with LFRAME, which should be "more general",
even though it would probably require many more changes than this to
get this coder to work for other frame sizes.
@
text
@d6 8
d22 25
d51 3
a57 8
*   Detection of onsets in (or slightly preceding) the futuremost frame
*   of speech.

*   Arguments
*    PEBUF	Preemphasized speech
*    OSBUF	Buffer which holds sorted indexes of onsets (Modified)
*    OSPTR	Free pointer into OSBUF (Modified)

d62 1
a62 1
*    OSHYST	The number of samples which of slope(FPC) which must be below
a63 4
*   Variables
*    N, D       Numerator and denominator of prediction filters
*    FPC        Current prediction coefs
*    L2BUF, L2SUM1, L2SUM2    State of slope filter
d70 17
a86 6
*       All of the following local variables, except I, were SAVE'd in
*       the original code.  All of them need to be except for L2SUM2,
*       and L2SUM1 need not be, but avoiding saving it would require a
*       small change to the body of the code.  See comments below for
*       an example of how the code could be changed to avoid saving
*       L2SUM1.
d96 2
a97 2
	REAL L2BUF(L2WID), L2SUM1, L2SUM2
	INTEGER L2PTR1, L2PTR2, I, LASTI
d101 1
a101 1
	DATA L2SUM1/0./, L2SUM2/0./
d104 1
d106 3
a108 2
	SAVE L2BUF, L2PTR1, L2PTR2, L2SUM1, L2SUM2
	SAVE HYST, LASTI
d112 1
a112 1
*       MAXFRM.  I changed it to LFRAME, for "cleanliness".
d180 16
@


1.1
log
@Initial revision
@
text
@d5 4
a8 1
* $Log$
d46 14
d73 5
a77 1
	IF (HYST) LASTI = LASTI - 180
d91 27
d134 4
@