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Preventing encoder-decoder mismatch when energy values are too large to be
represented by the laplace encoder (would have a probability of zero due
to finite precision)

--- a/libcelt/laplace.c

+++ b/libcelt/laplace.c

@@ -40,19 +40,20 @@

    return (((ec_uint32)32767)*(16384-decay))/(16384+decay);

 }

-void ec_laplace_encode_start(ec_enc *enc, int value, int decay, int fs)

+void ec_laplace_encode_start(ec_enc *enc, int *value, int decay, int fs)

 {

    int i;

    int fl, ft;

    int s = 0;

-   if (value < 0)

+   int val = *value;

+   if (val < 0)

    {

       s = 1;

-      value = -value;

+      val = -val;

    }

    ft = 32767;

    fl = -fs;

-   for (i=0;i<value;i++)

+   for (i=0;i<val;i++)

    {

       int tmp_l, tmp_s;

       tmp_l = fl;

@@ -63,6 +64,10 @@

       {

          fs = tmp_s;

          fl = tmp_l;

+         if (s)

+            *value = -i;

+         else

+            *value = i;

          break;

       }

    }

@@ -75,7 +80,7 @@

    ec_encode(enc, fl, fl+fs, ft);

 }

-void ec_laplace_encode(ec_enc *enc, int value, int decay)

+void ec_laplace_encode(ec_enc *enc, int *value, int decay)

 {

    int fs = ec_laplace_get_start_freq(decay);

    ec_laplace_encode_start(enc, value, decay, fs);

--- a/libcelt/laplace.h

+++ b/libcelt/laplace.h

@@ -40,9 +40,9 @@

  @param value Value to encode

  @param decay Probability of the value +/- 1, multiplied by 16384

 */

-void ec_laplace_encode(ec_enc *enc, int value, int decay);

+void ec_laplace_encode(ec_enc *enc, int *value, int decay);

-void ec_laplace_encode_start(ec_enc *enc, int value, int decay, int fs);

+void ec_laplace_encode_start(ec_enc *enc, int *value, int decay, int fs);

 /** Decode a value that is assumed to be the realisation of a

     Laplace-distributed random process

--- a/libcelt/quant_bands.c

+++ b/libcelt/quant_bands.c

@@ -179,7 +179,7 @@

       if (ec_enc_tell(enc, 0) - bits > budget+16)

          qi = -1;

       else

-         ec_laplace_encode_start(enc, qi, prob[2*i], prob[2*i+1]);

+         ec_laplace_encode_start(enc, &qi, prob[2*i], prob[2*i+1]);

       q = qi*base_resolution;

       error[i] = f - SHL16(qi,8);