[FFmpeg-soc] [soc]: r3730 - in eac3: ac3dec.c eac3dec.c

[jbr]

Author: jbr
Date: Mon Sep  8 05:48:45 2008
New Revision: 3730

Log:
decode and apply SPX coordinates

Modified:
   eac3/ac3dec.c
   eac3/eac3dec.c

Modified: eac3/ac3dec.c
==============================================================================
--- eac3/ac3dec.c	(original)
+++ eac3/ac3dec.c	Mon Sep  8 05:48:45 2008
@@ -848,12 +848,15 @@ static int decode_audio_block(AC3DecodeC
             if (s->channel_in_spx[ch]) {
                 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
                     int bin, spx_blend;
+                    int master_spx_coord;
                     s->first_spx_coords[ch] = 0;
                     s->spx_coords_exist[ch] = 1;
                     spx_blend = get_bits(gbc, 5) << 18;
-                    skip_bits(gbc, 2); // skip master spx coord
+                    master_spx_coord = get_bits(gbc, 2) * 3;
                     bin = s->spx_start_freq;
                     for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
+                        int spx_coord_exp, spx_coord_mant;
+
                         /* calculate blending factors */
                         int bandsize = s->spx_band_sizes[bnd];
                         int nratio = (((bin + (bandsize >> 1)) << 23) / s->spx_end_freq) - spx_blend;
@@ -862,8 +865,14 @@ static int decode_audio_block(AC3DecodeC
                         s->spx_signal_blend[ch][bnd] = ff_sqrt((INT24_MAX - nratio) << 8) * M_SQRT_POW2_15;
                         bin += bandsize;
 
-                        skip_bits(gbc, 4); // skip spx coord exponent
-                        skip_bits(gbc, 2); // skip spx coord mantissa
+                        /* decode coupling coordinates */
+                        spx_coord_exp  = get_bits(gbc, 4);
+                        spx_coord_mant = get_bits(gbc, 2);
+                        if (spx_coord_exp == 15)
+                            s->spx_coords[ch][bnd] = spx_coord_mant << 26;
+                        else
+                            s->spx_coords[ch][bnd] = (spx_coord_mant + 4) << 25;
+                        s->spx_coords[ch][bnd] >>= (spx_coord_exp + master_spx_coord);
                     }
                 } else {
                     s->spx_coords_exist[ch] = 0;

Modified: eac3/eac3dec.c
==============================================================================
--- eac3/eac3dec.c	(original)
+++ eac3/eac3dec.c	Mon Sep  8 05:48:45 2008
@@ -115,20 +115,20 @@ void ff_eac3_apply_spectral_extension(AC
             }
         }
 
-        /* Apply coefficient and noise scaling based on previously calculated
-           RMS energy and blending factors for each band. */
+        /* Apply noise-blended coefficient scaling based on previously
+           calculated RMS energy, blending factors, and SPX coordinates for
+           each band. */
         bin = s->spx_start_freq;
         for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
             int64_t nscale = (s->spx_noise_blend [ch][bnd] * rms_energy[bnd]) >> 23;
-            int64_t sscale =  s->spx_signal_blend[ch][bnd];
+            int64_t sscale = s->spx_signal_blend[ch][bnd];
+            int64_t spxco  = s->spx_coords[ch][bnd];
             for (i = 0; i < s->spx_band_sizes[bnd]; i++) {
-                int64_t noise  = nscale * (av_znrng_get(&s->spx_noise_state) >> 5);
-                int64_t signal = sscale * s->fixed_coeffs[ch][bin];
-                s->fixed_coeffs[ch][bin++] = (noise + signal) >> 23;
+                int64_t noise  = (nscale * (av_znrng_get(&s->spx_noise_state) >> 4)) >> 23;
+                int64_t signal = (sscale * s->fixed_coeffs[ch][bin]) >> 23;
+                s->fixed_coeffs[ch][bin++] = ((noise + signal) * spxco) >> 23;
             }
         }
-
-        /* Scale coefficients using spectral extension coordinates */
     }
 }