Remove the add bias hack for the C version of DSPContext.float_to_int16_*().

(cherry picked from commit 9d06d7bce3babb82ed650c13ed13a57f6f626a71)

1 files changed, 16 insertions, 26 deletions

diff --git a/libavcodec/aacdec.c b/libavcodec/aacdec.c
index fd65b1c3ba..fddec17fcc 100644
--- a/libavcodec/aacdec.c
+++ b/libavcodec/aacdec.c
@@ -566,18 +566,10 @@ static av_cold int aac_decode_init(AVCodecContext *avctx)
     ac->random_state = 0x1f2e3d4c;
 
     // -1024 - Compensate wrong IMDCT method.
-    // 32768 - Required to scale values to the correct range for the bias method
-    //         for float to int16 conversion.
-
-    if (ac->dsp.float_to_int16_interleave == ff_float_to_int16_interleave_c) {
-        ac->add_bias  = 385.0f;
-        ac->sf_scale  = 1. / (-1024. * 32768.);
-        ac->sf_offset = 0;
-    } else {
-        ac->add_bias  = 0.0f;
+    // 60    - Required to scale values to the correct range [-32768,32767]
+    //         for float to int16 conversion. (1 << (60 / 4)) == 32768
         ac->sf_scale  = 1. / -1024.;
         ac->sf_offset = 60;
-    }
 
     ff_aac_tableinit();
 
@@ -1701,7 +1693,7 @@ static void apply_tns(float coef[1024], TemporalNoiseShaping *tns,
 /**
  * Conduct IMDCT and windowing.
  */
-static void imdct_and_windowing(AACContext *ac, SingleChannelElement *sce, float bias)
+static void imdct_and_windowing(AACContext *ac, SingleChannelElement *sce)
 {
     IndividualChannelStream *ics = &sce->ics;
     float *in    = sce->coeffs;
@@ -1729,29 +1721,29 @@ static void imdct_and_windowing(AACContext *ac, SingleChannelElement *sce, float
      */
     if ((ics->window_sequence[1] == ONLY_LONG_SEQUENCE || ics->window_sequence[1] == LONG_STOP_SEQUENCE) &&
             (ics->window_sequence[0] == ONLY_LONG_SEQUENCE || ics->window_sequence[0] == LONG_START_SEQUENCE)) {
-        ac->dsp.vector_fmul_window(    out,               saved,            buf,         lwindow_prev, bias, 512);
+        ac->dsp.vector_fmul_window(    out,               saved,            buf,         lwindow_prev, 0, 512);
     } else {
         for (i = 0; i < 448; i++)
-            out[i] = saved[i] + bias;
+            out[i] = saved[i];
 
         if (ics->window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
-            ac->dsp.vector_fmul_window(out + 448 + 0*128, saved + 448,      buf + 0*128, swindow_prev, bias, 64);
-            ac->dsp.vector_fmul_window(out + 448 + 1*128, buf + 0*128 + 64, buf + 1*128, swindow,      bias, 64);
-            ac->dsp.vector_fmul_window(out + 448 + 2*128, buf + 1*128 + 64, buf + 2*128, swindow,      bias, 64);
-            ac->dsp.vector_fmul_window(out + 448 + 3*128, buf + 2*128 + 64, buf + 3*128, swindow,      bias, 64);
-            ac->dsp.vector_fmul_window(temp,              buf + 3*128 + 64, buf + 4*128, swindow,      bias, 64);
+            ac->dsp.vector_fmul_window(out + 448 + 0*128, saved + 448,      buf + 0*128, swindow_prev, 0, 64);
+            ac->dsp.vector_fmul_window(out + 448 + 1*128, buf + 0*128 + 64, buf + 1*128, swindow,      0, 64);
+            ac->dsp.vector_fmul_window(out + 448 + 2*128, buf + 1*128 + 64, buf + 2*128, swindow,      0, 64);
+            ac->dsp.vector_fmul_window(out + 448 + 3*128, buf + 2*128 + 64, buf + 3*128, swindow,      0, 64);
+            ac->dsp.vector_fmul_window(temp,              buf + 3*128 + 64, buf + 4*128, swindow,      0, 64);
             memcpy(                    out + 448 + 4*128, temp, 64 * sizeof(float));
         } else {
-            ac->dsp.vector_fmul_window(out + 448,         saved + 448,      buf,         swindow_prev, bias, 64);
+            ac->dsp.vector_fmul_window(out + 448,         saved + 448,      buf,         swindow_prev, 0, 64);
             for (i = 576; i < 1024; i++)
-                out[i] = buf[i-512] + bias;
+                out[i] = buf[i-512];
         }
     }
 
     // buffer update
     if (ics->window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
         for (i = 0; i < 64; i++)
-            saved[i] = temp[64 + i] - bias;
+            saved[i] = temp[64 + i];
         ac->dsp.vector_fmul_window(saved + 64,  buf + 4*128 + 64, buf + 5*128, swindow, 0, 64);
         ac->dsp.vector_fmul_window(saved + 192, buf + 5*128 + 64, buf + 6*128, swindow, 0, 64);
         ac->dsp.vector_fmul_window(saved + 320, buf + 6*128 + 64, buf + 7*128, swindow, 0, 64);
@@ -1811,13 +1803,12 @@ static void apply_independent_coupling(AACContext *ac,
 {
     int i;
     const float gain = cce->coup.gain[index][0];
-    const float bias = ac->add_bias;
     const float *src = cce->ch[0].ret;
     float *dest = target->ret;
     const int len = 1024 << (ac->m4ac.sbr == 1);
 
     for (i = 0; i < len; i++)
-        dest[i] += gain * (src[i] - bias);
+        dest[i] += gain * src[i];
 }
 
 /**
@@ -1861,7 +1852,6 @@ static void apply_channel_coupling(AACContext *ac, ChannelElement *cc,
 static void spectral_to_sample(AACContext *ac)
 {
     int i, type;
-    float imdct_bias = (ac->m4ac.sbr <= 0) ? ac->add_bias : 0.0f;
     for (type = 3; type >= 0; type--) {
         for (i = 0; i < MAX_ELEM_ID; i++) {
             ChannelElement *che = ac->che[type][i];
@@ -1875,9 +1865,9 @@ static void spectral_to_sample(AACContext *ac)
                 if (type <= TYPE_CPE)
                     apply_channel_coupling(ac, che, type, i, BETWEEN_TNS_AND_IMDCT, apply_dependent_coupling);
                 if (type != TYPE_CCE || che->coup.coupling_point == AFTER_IMDCT) {
-                    imdct_and_windowing(ac, &che->ch[0], imdct_bias);
+                    imdct_and_windowing(ac, &che->ch[0]);
                     if (type == TYPE_CPE) {
-                        imdct_and_windowing(ac, &che->ch[1], imdct_bias);
+                        imdct_and_windowing(ac, &che->ch[1]);
                     }
                     if (ac->m4ac.sbr > 0) {
                         ff_sbr_apply(ac, &che->sbr, type, che->ch[0].ret, che->ch[1].ret);