ref: bd5d54adb837b94ba648e9f7770b59bf64cb4e6c
parent: 328b8bd7fcfc63240f78a590c7349cf58c9936f0
author: Jean-Marc Valin <[email protected]>
date: Mon Oct 19 20:25:31 EDT 2009
New VBR rate controller that doesn't allow more than one frame worth of excess bit-rate
--- a/libcelt/celt.c
+++ b/libcelt/celt.c
@@ -92,7 +92,13 @@
int fold_decision;
celt_word16 gain_prod;
- int VBR_rate; /* Target number of 16th bits per frame */
+ /* VBR-related parameters */
+ celt_int32 vbr_reservoir;
+ celt_int32 vbr_drift;
+ celt_int32 vbr_offset;
+ celt_int32 vbr_count;
+
+ celt_int32 vbr_rate; /* Target number of 16th bits per frame */
celt_word16 * restrict preemph_memE;
celt_sig * restrict preemph_memD;
@@ -133,6 +139,16 @@
*error = CELT_INVALID_MODE;
return NULL;
}
+#ifdef DISABLE_STEREO
+ if (channels > 1)
+ {+ celt_warning("Stereo support was disable from this build");+ if (error)
+ *error = CELT_BAD_ARG;
+ return NULL;
+ }
+#endif
+
if (channels < 0 || channels > 2)
{ celt_warning("Only mono and stereo supported");@@ -158,7 +174,7 @@
st->overlap = mode->overlap;
st->channels = channels;
- st->VBR_rate = 0;
+ st->vbr_rate = 0;
st->pitch_enabled = 1;
st->pitch_permitted = 1;
st->pitch_available = 1;
@@ -662,7 +678,7 @@
compute_band_energies(st->mode, freq, bandE, C);
for (i=0;i<st->mode->nbEBands*C;i++)
bandLogE[i] = amp2Log(bandE[i]);
-
+
/* Band normalisation */
normalise_bands(st->mode, freq, X, bandE, C);
if (!shortBlocks && !folding_decision(st->mode, X, &st->tonal_average, &st->fold_decision, C))
@@ -754,10 +770,12 @@
coarse_needed = ((coarse_needed*3-1)>>3)+1;
/* Variable bitrate */
- if (st->VBR_rate>0)
+ if (st->vbr_rate>0)
{+ celt_word16 alpha;
+ celt_int32 delta, vbr_bound;
/* The target rate in 16th bits per frame */
- int target=st->VBR_rate;
+ celt_int32 target=st->vbr_rate;
/* Shortblocks get a large boost in bitrate, but since they
are uncommon long blocks are not greatly effected */
@@ -764,15 +782,57 @@
if (shortBlocks)
target*=2;
else if (st->mode->nbShortMdcts > 1)
- target-=(target+14)/28;
+ target-=(target+14)/28;
/* The average energy is removed from the target and the actual
energy added*/
- target=target-588+ec_enc_tell(&enc, BITRES);
+ target=target+st->vbr_offset-588+ec_enc_tell(&enc, BITRES);
/* In VBR mode the frame size must not be reduced so much that it would result in the coarse energy busting its budget */
target=IMAX(coarse_needed,(target+64)/128);
nbCompressedBytes=IMIN(nbCompressedBytes,target);
+
+ /* Make the adaptation coef (alpha) higher at the beginning */
+ if (st->vbr_count < 990)
+ {+ st->vbr_count++;
+ alpha = celt_rcp(SHL32(EXTEND32(st->vbr_count+10),16));
+ /*printf ("%d %d\n", st->vbr_count+10, alpha);*/+ } else
+ alpha = QCONST16(.001f,15);
+
+ /* By how much did we "miss" the target on that frame */
+ delta = (8<<BITRES)*(celt_int32)nbCompressedBytes - st->vbr_rate;
+ /* How many bits have we used in excess of what we're allowed */
+ st->vbr_reservoir += delta;
+ /*printf ("%d\n", st->vbr_reservoir);*/+
+ /* Compute the offset we need to apply in order to reach the target */
+ st->vbr_drift += MULT16_32_Q15(alpha,delta-st->vbr_offset-st->vbr_drift);
+ st->vbr_offset = -st->vbr_drift;
+ /*printf ("%d\n", st->vbr_drift);*/+
+ /* We could use any multiple of vbr_rate as bound (depending on the delay) */
+ vbr_bound = st->vbr_rate;
+ if (st->vbr_reservoir > vbr_bound)
+ {+ /* Busted the reservoir -- reduce the rate */
+ int adjust = 1+(st->vbr_reservoir-vbr_bound-1)/(8<<BITRES);
+ nbCompressedBytes -= adjust;
+ st->vbr_reservoir -= adjust*(8<<BITRES);
+ st->vbr_offset -= 8<<BITRES;
+ /*printf ("-%d\n", adjust);*/+ } else if (st->vbr_reservoir < 0)
+ {+ /* We're under the min value -- increase rate */
+ int adjust = 1-(st->vbr_reservoir-1)/(8<<BITRES);
+ st->vbr_reservoir += adjust*(8<<BITRES);
+ nbCompressedBytes += adjust;
+ st->vbr_offset += 8<<BITRES;
+ /*printf ("+%d\n", adjust);*/+ }
+
+ /* This moves the raw bits to take into account the new compressed size */
ec_byte_shrink(&buf, nbCompressedBytes);
}
@@ -962,8 +1022,8 @@
goto bad_arg;
if (value>3072000)
value = 3072000;
- st->VBR_rate = ((st->mode->Fs<<3)+(st->block_size>>1))/st->block_size;
- st->VBR_rate = ((value<<7)+(st->VBR_rate>>1))/st->VBR_rate;
+ st->vbr_rate = ((st->mode->Fs<<3)+(st->block_size>>1))/st->block_size;
+ st->vbr_rate = ((value<<7)+(st->vbr_rate>>1))/st->vbr_rate;
}
break;
case CELT_RESET_STATE:
@@ -1066,6 +1126,16 @@
*error = CELT_INVALID_MODE;
return NULL;
}
+#ifdef DISABLE_STEREO
+ if (channels > 1)
+ {+ celt_warning("Stereo support was disable from this build");+ if (error)
+ *error = CELT_BAD_ARG;
+ return NULL;
+ }
+#endif
+
if (channels < 0 || channels > 2)
{ celt_warning("Only mono and stereo supported");