shithub: opus

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cleaned up transient_analysis() and replaced the algorithm with a simpler one
based on the max absolute value in a range.

--- a/libcelt/celt.c

+++ b/libcelt/celt.c

@@ -164,80 +164,55 @@

    return (celt_int16_t)floor(.5+x);

 #endif

 }

-#ifdef FIXED_POINT

-static int ratio_compare(celt_word32_t num1, celt_word32_t den1, celt_word32_t num2, celt_word32_t den2)

-{

-   int shift = celt_zlog2(MAX32(num1, num2));

-   if (shift > 14)

-   {

-      num1 = SHR32(num1, shift-14);

-      num2 = SHR32(num2, shift-14);

-   }

-   shift = celt_zlog2(MAX32(den1, den2));

-   if (shift > 14)

-   {

-      den1 = SHR32(den1, shift-14);

-      den2 = SHR32(den2, shift-14);

-   }

-   return MULT16_16(EXTRACT16(num1),EXTRACT16(den2)) > MULT16_16(EXTRACT16(den1),EXTRACT16(num2));

-}

-#else

-static int ratio_compare(celt_word32_t num1, celt_word32_t den1, celt_word32_t num2, celt_word32_t den2)

-{

-   return num1*den2 > den1*num2;

-}

-#endif

-static int transient_analysis(celt_word32_t *in, int len, int C, celt_word32_t *r)

+static int transient_analysis(celt_word32_t *in, int len, int C, int *transient_time, int *transient_shift)

 {

    int c, i, n;

    celt_word32_t ratio;

    /* FIXME: Remove the floats here */

-   celt_word32_t maxN, maxD;

    VARDECL(celt_word32_t, begin);

    SAVE_STACK;

    ALLOC(begin, len, celt_word32_t);

-   

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

       begin[i] = EXTEND32(ABS16(SHR32(in[C*i],SIG_SHIFT)));

    for (c=1;c<C;c++)

    {

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

-         begin[i] = ADD32(begin[i], EXTEND32(ABS16(SHR32(in[C*i+c],SIG_SHIFT))));

+         begin[i] = MAX32(begin[i], EXTEND32(ABS16(SHR32(in[C*i+c],SIG_SHIFT))));

    }

    for (i=1;i<len;i++)

-      begin[i] = begin[i-1]+begin[i];

-

-   maxD = VERY_LARGE32;

-   maxN = 0;

+      begin[i] = MAX32(begin[i-1],begin[i]);

    n = -1;

    for (i=8;i<len-8;i++)

    {

-      celt_word32_t endi;

-      celt_word32_t num, den;

-      endi = begin[len-1]-begin[i];

-      num = endi*i;

-      den = (30+begin[i])*(len-i)+MULT16_32_Q15(QCONST16(.1f,15),endi)*len;

-      if (ratio_compare(num, den, maxN, maxD) && (endi > MULT16_32_Q15(QCONST16(.05f,15),begin[i])))

-      {

-         maxN = num;

-         maxD = den;

-         n = i;

-      }

+      if (begin[i] < MULT16_32_Q15(QCONST16(.2f,15),begin[len-1]))

+         n=i;

    }

-   ratio = DIV32((begin[len-1]-begin[n])*n,(10+begin[n])*(len-n));

    if (n<32)

    {

       n = -1;

       ratio = 0;

+   } else {

+      ratio = DIV32(begin[len-1],1+begin[n-16]);

    }

+   /*printf ("%d %f\n", n, ratio*ratio);*/

    if (ratio < 0)

       ratio = 0;

    if (ratio > 1000)

       ratio = 1000;

-   *r = ratio*ratio;

+   ratio *= ratio;

+   if (ratio < 50)

+      *transient_shift = 0;

+   else if (ratio < 256)

+      *transient_shift = 1;

+   else if (ratio < 4096)

+      *transient_shift = 2;

+   else

+      *transient_shift = 3;

+   *transient_time = n;

+   

    RESTORE_STACK;

-   return n;

+   return ratio > 20;

 }

 /** Apply window and compute the MDCT for all sub-frames and all channels in a frame */

@@ -400,7 +375,6 @@

    int shortBlocks=0;

    int transient_time;

    int transient_shift;

-   celt_word32_t maxR;

    const int C = CHANNELS(st->mode);

    SAVE_STACK;

@@ -428,26 +402,12 @@

    }

    CELT_COPY(st->in_mem, in+C*(2*N-2*N4-st->overlap), C*st->overlap);

-   transient_time = transient_analysis(in, N+st->overlap, C, &maxR);

-   if (maxR > 30)

+   if (transient_analysis(in, N+st->overlap, C, &transient_time, &transient_shift))

    {

 #ifndef FIXED_POINT

       float gain_1;

 #endif

       ec_enc_bits(&st->enc, 1, 1);

-      if (maxR < 30)

-      {

-         transient_shift = 0;

-      } else if (maxR < 100)

-      {

-         transient_shift = 1;

-      } else if (maxR < 500)

-      {

-         transient_shift = 2;

-      } else

-      {

-         transient_shift = 3;

-      }

       ec_enc_bits(&st->enc, transient_shift, 2);

       if (transient_shift)

          ec_enc_uint(&st->enc, transient_time, N+st->overlap);