Add a shift parameter to celp_lp_synthesis_filter()

This is intended for reuse by the G.723.1 decoder
Signed-off-by: Kostya Shishkov <kostya.shishkov@gmail.com>

libavcodec/celp_filters.c

@@ -58,7 +58,7 @@ void ff_celp_circ_addf(float *out, const float *in,
 int ff_celp_lp_synthesis_filter(int16_t *out, const int16_t *filter_coeffs,
                                 const int16_t *in, int buffer_length,
                                 int filter_length, int stop_on_overflow,
-                                int rounder)
+                                int shift, int rounder)
 {
     int i,n;
 
@@ -67,7 +67,7 @@ int ff_celp_lp_synthesis_filter(int16_t *out, const int16_t *filter_coeffs,
         for (i = 1; i <= filter_length; i++)
             sum -= filter_coeffs[i-1] * out[n-i];
 
-        sum = (sum >> 12) + in[n];
+        sum = ((sum >> 12) + in[n]) >> shift;
 
         if (sum + 0x8000 > 0xFFFFU) {
             if (stop_on_overflow)

libavcodec/celp_filters.h

@@ -63,6 +63,7 @@ void ff_celp_circ_addf(float *out, const float *in,
  * @param filter_length filter length (10 for 10th order LP filter)
  * @param stop_on_overflow   1 - return immediately if overflow occurs
  *                           0 - ignore overflows
+ * @param shift the result is shifted right by this value
  * @param rounder the amount to add for rounding (usually 0x800 or 0xfff)
  *
  * @return 1 if overflow occurred, 0 - otherwise
@@ -75,7 +76,7 @@ void ff_celp_circ_addf(float *out, const float *in,
 int ff_celp_lp_synthesis_filter(int16_t *out, const int16_t *filter_coeffs,
                                 const int16_t *in, int buffer_length,
                                 int filter_length, int stop_on_overflow,
-                                int rounder);
+                                int shift, int rounder);
 
 /**
  * LP synthesis filter.

libavcodec/ra144.c

@@ -1715,6 +1715,6 @@ void ff_subblock_synthesis(RA144Context *ractx, const uint16_t *lpc_coefs,
            LPC_ORDER*sizeof(*ractx->curr_sblock));
 
     if (ff_celp_lp_synthesis_filter(ractx->curr_sblock + LPC_ORDER, lpc_coefs,
-                                    block, BLOCKSIZE, LPC_ORDER, 1, 0xfff))
+                                    block, BLOCKSIZE, LPC_ORDER, 1, 0, 0xfff))
         memset(ractx->curr_sblock, 0, (LPC_ORDER+BLOCKSIZE)*sizeof(*ractx->curr_sblock));
 }