lavc/lpc: Add min_shift parameter in LPC

The min_shift parameter is needed by the MLP encoder
Signed-off-by: Jai Luthra <me@jailuthra.in>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/alacenc.c

@@ -38,6 +38,7 @@
 #define DEFAULT_MAX_PRED_ORDER    6
 #define DEFAULT_MIN_PRED_ORDER    4
 #define ALAC_MAX_LPC_PRECISION    9
+#define ALAC_MIN_LPC_SHIFT        0
 #define ALAC_MAX_LPC_SHIFT        9
 
 #define ALAC_CHMODE_LEFT_RIGHT    0
@@ -171,7 +172,8 @@ static void calc_predictor_params(AlacEncodeContext *s, int ch)
                                       s->max_prediction_order,
                                       ALAC_MAX_LPC_PRECISION, coefs, shift,
                                       FF_LPC_TYPE_LEVINSON, 0,
-                                      ORDER_METHOD_EST, ALAC_MAX_LPC_SHIFT, 1);
+                                      ORDER_METHOD_EST, ALAC_MIN_LPC_SHIFT,
+                                      ALAC_MAX_LPC_SHIFT, 1);
 
         s->lpc[ch].lpc_order = opt_order;
         s->lpc[ch].lpc_quant = shift[opt_order-1];

libavcodec/flacenc.c

@@ -44,6 +44,7 @@
 #define MAX_PARTITION_ORDER 8
 #define MAX_PARTITIONS     (1 << MAX_PARTITION_ORDER)
 #define MAX_LPC_PRECISION  15
+#define MIN_LPC_SHIFT       0
 #define MAX_LPC_SHIFT      15
 
 enum CodingMode {
@@ -884,7 +885,7 @@ static int encode_residual_ch(FlacEncodeContext *s, int ch)
     opt_order = ff_lpc_calc_coefs(&s->lpc_ctx, smp, n, min_order, max_order,
                                   s->options.lpc_coeff_precision, coefs, shift, s->options.lpc_type,
                                   s->options.lpc_passes, omethod,
-                                  MAX_LPC_SHIFT, 0);
+                                  MIN_LPC_SHIFT, MAX_LPC_SHIFT, 0);
 
     if (omethod == ORDER_METHOD_2LEVEL ||
         omethod == ORDER_METHOD_4LEVEL ||

libavcodec/lpc.c

@@ -93,7 +93,8 @@ static void lpc_compute_autocorr_c(const double *data, int len, int lag,
  * Quantize LPC coefficients
  */
 static void quantize_lpc_coefs(double *lpc_in, int order, int precision,
-                               int32_t *lpc_out, int *shift, int max_shift, int zero_shift)
+                               int32_t *lpc_out, int *shift, int min_shift,
+                               int max_shift, int zero_shift)
 {
     int i;
     double cmax, error;
@@ -118,7 +119,7 @@ static void quantize_lpc_coefs(double *lpc_in, int order, int precision,
 
     /* calculate level shift which scales max coeff to available bits */
     sh = max_shift;
-    while((cmax * (1 << sh) > qmax) && (sh > 0)) {
+    while((cmax * (1 << sh) > qmax) && (sh > min_shift)) {
         sh--;
     }
 
@@ -201,7 +202,7 @@ int ff_lpc_calc_coefs(LPCContext *s,
                       int max_order, int precision,
                       int32_t coefs[][MAX_LPC_ORDER], int *shift,
                       enum FFLPCType lpc_type, int lpc_passes,
-                      int omethod, int max_shift, int zero_shift)
+                      int omethod, int min_shift, int max_shift, int zero_shift)
 {
     double autoc[MAX_LPC_ORDER+1];
     double ref[MAX_LPC_ORDER] = { 0 };
@@ -284,10 +285,12 @@ int ff_lpc_calc_coefs(LPCContext *s,
     if(omethod == ORDER_METHOD_EST) {
         opt_order = estimate_best_order(ref, min_order, max_order);
         i = opt_order-1;
-        quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i], max_shift, zero_shift);
+        quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i],
+                           min_shift, max_shift, zero_shift);
     } else {
         for(i=min_order-1; i<max_order; i++) {
-            quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i], max_shift, zero_shift);
+            quantize_lpc_coefs(lpc[i], i+1, precision, coefs[i], &shift[i],
+                               min_shift, max_shift, zero_shift);
         }
     }
 

libavcodec/lpc.h

@@ -95,7 +95,7 @@ int ff_lpc_calc_coefs(LPCContext *s,
                       int max_order, int precision,
                       int32_t coefs[][MAX_LPC_ORDER], int *shift,
                       enum FFLPCType lpc_type, int lpc_passes,
-                      int omethod, int max_shift, int zero_shift);
+                      int omethod, int min_shift, int max_shift, int zero_shift);
 
 int ff_lpc_calc_ref_coefs(LPCContext *s,
                           const int32_t *samples, int order, double *ref);

libavcodec/ra144enc.c

@@ -475,7 +475,7 @@ static int ra144_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
 
     ff_lpc_calc_coefs(&ractx->lpc_ctx, lpc_data, NBLOCKS * BLOCKSIZE, LPC_ORDER,
                       LPC_ORDER, 16, lpc_coefs, shift, FF_LPC_TYPE_LEVINSON,
-                      0, ORDER_METHOD_EST, 12, 0);
+                      0, ORDER_METHOD_EST, 0, 12, 0);
     for (i = 0; i < LPC_ORDER; i++)
         block_coefs[NBLOCKS - 1][i] = -(lpc_coefs[LPC_ORDER - 1][i] <<
                                         (12 - shift[LPC_ORDER - 1]));