pitsyn.f,v

lpc10-15为美军2400bps语音压缩标准的C语音源代码。

* concrete.  If LFRAME is ever changed, keep this in mind.  Similarly,
* 135's are 3*LFRAME/4, and 45's are LFRAME/4.  If LFRAME is not a
* multiple of 4, then the 135 for NL-JSAMP is actually LFRAME-LFRAME/4,
* and the 45 for NL-JSAMP is actually LFRAME-3*LFRAME/4.
* 
* Note that LSAMP-JSAMP is given as the variable.  This was just for
* brevity, to avoid adding "+JSAMP" to all of the column entries.
* Similarly for NL-JSAMP.
* 
* Variable    | 000  001    011,010  111       110       100,101
* ------------+--------------------------------------------------
* ISTART      | 1    NL+1   NL+1     1         1         1
* LSAMP-JSAMP | 180  180    180      180       135       45
* IPITO       | 45   PITCH  PITCH    oldPITCH  oldPITCH  oldPITCH
* SLOPE       | 0    0      0        seebelow  0         0
* JUSED       | 0    NL     NL       0         0         0
* PITCH       | 45   PITCH  PITCH    PITCH     PITCH     PITCH
* NL-JSAMP    | --   135    45       --        --        --
* VFLAG       | 0    0      0        0         1         1
* NOUT        | 0    2      2        0         0         0
* IVOICE      | 0    1      1        1         1         1
* 
* while_loop  | once once   once     once      twice     twice
* 
* ISTART      | --   --     --       --        JUSED+1   JUSED+1
* LSAMP-JSAMP | --   --     --       --        180       180
* IPITO       | --   --     --       --        oldPITCH  oldPITCH
* SLOPE       | --   --     --       --        0         0
* JUSED       | --   --     --       --        ??        ??
* PITCH       | --   --     --       --        PITCH     PITCH
* NL-JSAMP    | --   --     --       --        --        --
* VFLAG       | --   --     --       --        0         0
* NOUT        | --   --     --       --        ??        ??
* IVOICE      | --   --     --       --        0         0
* 
* 
* UVPIT is always 0.0 on the first pass through the DO WHILE (.TRUE.)
* loop below.
* 
* The only possible non-0 value of SLOPE (in column 111) is
* (PITCH-IPITO)/FLOAT(LSAMP)
* 
* Column 101 is identical to 100.  Any good properties we can prove
* for 100 will also hold for 101.  Similarly for 010 and 011.
* 
* SYNTHS calls this subroutine with PITCH restricted to the range 20 to
* 156.  IPITO is similarly restricted to this range, after the first
* call.  IP below is also restricted to this range, given the
* definitions of IPITO, SLOPE, UVPIT, and that I is in the range ISTART
* to LSAMP.
* 
	   DO WHILE (.TRUE.)
*             
*             JUSED is the total length of all pitch periods currently
*             in the output arrays, in samples.
*             
*             An invariant of the DO I = ISTART,LSAMP loop below, under
*             the condition that IP is always in the range 1 through
*             MAXPIT, is:
*             
*             (I - MAXPIT) .LE. JUSED .LE. (I-1)
*             
*             Note that the final value of I is LSAMP+1, so that after
*             the DO loop is complete, we know:
*             
*             (LSAMP - MAXPIT + 1) .LE. JUSED .LE. LSAMP
*             
	      DO I = ISTART,LSAMP
	         IP = IPITO + SLOPE*I + .5
	         IF (UVPIT .NE. 0.0) IP = UVPIT
	         IF (IP .LE. I-JUSED) THEN
	            NOUT = NOUT + 1
*                   
*                   The following check is no longer necessary, now that
*                   we can prove that NOUT will never go over 16.
*                   
*		    IF (NOUT .GT. 16) STOP 'PITSYN: too many epochs'
*                   
	            IPITI(NOUT) = IP
	            PITCH = IP
	            IVUV(NOUT) = IVOICE
	            JUSED = JUSED + IP
	            PROP = (JUSED-IP/2)/FLOAT(LSAMP)
	            DO J = 1,ORDER
	               ALRO = ALOG((1+RCO(J))/(1-RCO(J)))
	               ALRN = ALOG((1+RC(J))/(1-RC(J)))
	               XXY = ALRO + PROP*(ALRN-ALRO)
	               XXY = EXP(XXY)
	               RCI(J,NOUT) = (XXY-1)/(XXY+1)
	            END DO
	            RMSI(NOUT) = ALOG(RMSO) + PROP*(ALOG(RMS)-ALOG(RMSO))
	            RMSI(NOUT) = EXP(RMSI(NOUT))
	         END IF
	      END DO
	      IF (VFLAG .NE. 1) GOTO 100
*             
*             I want to prove what range UVPIT must lie in after the
*             assignments to it below.  To do this, I must determine
*             what range (LSAMP-ISTART) must lie in, after the
*             assignments to ISTART and LSAMP below.
*             
*             Let oldLSAMP be the value of LSAMP at this point in the
*             execution.  This is 135+JSAMP in state 110, or 45+JSAMP in
*             states 100 or 101.
*             
*             Given the loop invariant on JUSED above, we know that:
*             
*             (oldLSAMP - MAXPIT + 1) .LE. JUSED .LE. oldLSAMP
*             
*             ISTART is one more than this.
*             
*             Let newLSAMP be the value assigned to LSAMP below.  This
*             is 180+JSAMP.  Thus (newLSAMP-oldLSAMP) is either 45 or
*             135, depending on the state.
*             
*             Thus, the range of newLSAMP-ISTART is:
*             
*             (newLSAMP-(oldLSAMP+1)) .LE. newLSAMP-ISTART
*             .LE. (newLSAMP-(oldLSAMP - MAXPIT + 2))
*             
*             or:
*             
*             46 .LE. newLSAMP-ISTART .LE. 133+MAXPIT .EQ. 289
*             
*             Therefore, UVPIT is in the range 23 to 144 after the first
*             assignment to UVPIT below, and after the conditional
*             assignment, it is in the range 23 to 90.
*             
*             The important thing is that it is in the range 20 to 156,
*             so that in the loop above, IP is always in this range.
*             
	      VFLAG = 0
	      ISTART = JUSED + 1
	      LSAMP = LFRAME + JSAMP
	      SLOPE = 0
	      IVOICE = 0
	      UVPIT = (LSAMP-ISTART)/2
	      IF (UVPIT .GT. 90) UVPIT = UVPIT/2
	      RMSO = RMS
	      DO I = 1,ORDER
	         RC(I) = YARC(I)
	         RCO(I) = YARC(I)
	      END DO
	   END DO
100	   JSAMP = LSAMP - JUSED
	END IF

*       Given that the maximum pitch period MAXPIT .LT. LFRAME (this is
*       currently true on every call, since SYNTHS always sets
*       LFRAME=180), NOUT will always be .GE. 1 at this point.

	IF (NOUT .NE. 0) THEN
	   IVOICO = VOICE(2)
	   IPITO = PITCH
	   RMSO = RMS
	   DO I = 1,ORDER
	      RCO(I) = RC(I)
	   END DO
	END IF
	RETURN


	ENTRY INITPITSYN ()

	RMSO = 1.
	FIRST = .TRUE.

	RETURN

	END
@


1.1
log
@Initial revision
@
text
@d5 4
a8 1
* $Log$
d14 1
a14 1
* Inputs:
d17 3
d21 5
a25 1
*  RMS    - Energy
d27 4
a30 2
*  LFRAME - Length of speech buffer
* Outputs:
d32 3
d39 5
d45 1
d50 20
a69 6
	INTEGER ORDER, VOICE(2), PITCH, LFRAME
	INTEGER IVUV(11), IPITI(11), NOUT
	REAL RMS, RC(ORDER), RMSI(11), RCI(ORDER,11), RATIO
	REAL RCO(MAXORD), YARC(MAXORD)
	INTEGER I, J, LSAMP, IP, IPITO, ISTART, IVOICE, IVOICO
	INTEGER JSAMP, JUSED, NL
d71 33
a103 1
	REAL RMSO, SLOPE, UVPIT, VFLAG, XXY
a104 1
	DATA FIRST/.TRUE./
d106 8
a113 2
	IF (RMS.LT.1) RMS = 1
	IF (RMSO.LT.1) RMSO = 1
d119 1
a119 1
	   IF (IVOICE.EQ.0) PITCH = LFRAME/4
d122 8
d146 2
a147 2
	   IF ((VOICE(1).EQ.IVOICO).AND.(VOICE(2).EQ.VOICE(1))) THEN
	      IF (VOICE(2).EQ.0) THEN
d151 1
a151 1
	         IF( RATIO.GT.8 ) RMSO = RMS
d157 2
a158 2
	      IF (IVOICO.NE.1) THEN
	         IF (IVOICO.EQ.VOICE(1)) THEN
d183 1
a183 1
	         IF (IVOICO.NE.VOICE(1)) THEN
d199 65
d265 15
d282 2
a283 2
	         IF (UVPIT.NE.0.0) IP = UVPIT
	         IF (IP.LE.I-JUSED) THEN
d285 6
a290 1
		    IF (NOUT .GT. 11) STOP 'PITSYN: too many epochs'
d307 37
a343 1
	      IF (VFLAG.NE.1) GOTO 100
d350 1
a350 1
	      IF(UVPIT.GT.90) UVPIT = UVPIT/2
d359 6
a364 1
	IF (NOUT.NE.0) THEN
d373 9
@