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Commenting the speech/music Markov code

--- a/src/analysis.c

+++ b/src/analysis.c

@@ -484,8 +484,14 @@

     /*printf("%f %f ", frame_probs[0], frame_probs[1]);*/

     {

-       float tau, beta;

+       /* Probability of state transition */

+       float tau;

+       /* Represents independence of the MLP probabilities, where

+          beta=1 means fully independent. */

+       float beta;

+       /* Denormalized probability of speech (p0) and music (p1) after update */

        float p0, p1;

+       /* Delayed decision variables */

        float s0, m0;

        float psum;

        float speech0;

@@ -501,13 +507,20 @@

           q = MAX16(.05f,MIN16(.95f,tonal->music_prob));

           beta = .01f+.05f*ABS16(p-q)/(p*(1-q)+q*(1-p));

        }

+       /* p0 and p1 are the probabilities of speech and music at this frame

+          using only information from previous frame and applying the

+          state transition model */

        p0 = (1-tonal->music_prob)*(1-tau) +    tonal->music_prob *tau;

        p1 =    tonal->music_prob *(1-tau) + (1-tonal->music_prob)*tau;

+       /* We apply the current probability with exponent beta to work around

+          the fact that the probability estimates aren't independent. */

        p0 *= (float)pow(1-frame_probs[0], beta);

        p1 *= (float)pow(frame_probs[0], beta);

+       /* Normalise the probabilities to get the Marokv probability of music. */

        tonal->music_prob = p1/(p0+p1);

        info->music_prob = tonal->music_prob;

+       /* This chunk of code deals with delayed decision. */

        psum=1e-20f;

        speech0 = (float)pow(1-frame_probs[0], beta);

        music0  = (float)pow(frame_probs[0], beta);