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opus/libcelt/quant_bands.c
Timothy B. Terriberry 76469c64b4 Prevent busts at low bitrates. 
This patch makes all symbols conditional on whether or not there's
 enough space left in the buffer to code them, and eliminates much
 of the redundancy in the side information.

A summary of the major changes:
* The isTransient flag is moved up to before the the coarse energy.
  If there are not enough bits to code the coarse energy, the flag
   would get forced to 0, meaning what energy values were coded
   would get interpreted incorrectly.
  This might not be the end of the world, and I'd be willing to
   move it back given a compelling argument.
* Coarse energy switches coding schemes when there are less than 15
   bits left in the packet:
  - With at least 2 bits remaining, the change in energy is forced
     to the range [-1...1] and coded with 1 bit (for 0) or 2 bits
     (for +/-1).
  - With only 1 bit remaining, the change in energy is forced to
     the range [-1...0] and coded with one bit.
  - If there is less than 1 bit remaining, the change in energy is
     forced to -1.
    This effectively low-passes bands whose energy is consistently
     starved; this might be undesirable, but letting the default be
     zero is unstable, which is worse.
* The tf_select flag gets moved back after the per-band tf_res
   flags again, and is now skipped entirely when none of the
   tf_res flags are set, and the default value is the same for
   either alternative.
* dynalloc boosting is now limited so that it stops once it's given
   a band all the remaining bits in the frame, or when it hits the
   "stupid cap" of (64<<LM)*(C<<BITRES) used during allocation.
* If dynalloc boosing has allocated all the remaining bits in the
   frame, the alloc trim parameter does not get encoded (it would
   have no effect).
* The intensity stereo offset is now limited to the range
   [start...codedBands], and thus doesn't get coded until after
   all of the skip decisions.
  Some space is reserved for it up front, and gradually given back
   as each band is skipped.
* The dual stereo flag is coded only if intensity>start, since
   otherwise it has no effect.
  It is now coded after the intensity flag.
* The space reserved for the final skip flag, the intensity stereo
   offset, and the dual stereo flag is now redistributed to all
   bands equally if it is unused.
  Before, the skip flag's bit was given to the band that stopped
   skipping without it (usually a dynalloc boosted band).

In order to enable simple interaction between VBR and these
 packet-size enforced limits, many of which are encountered before
 VBR is run, the maximum packet size VBR will allow is computed at
 the beginning of the encoding function, and the buffer reduced to
 that size immediately.
Later, when it is time to make the VBR decision, the minimum packet
 size is set high enough to ensure that no decision made thus far
 will have been affected by the packet size.
As long as this is smaller than the up-front maximum, all of the
 encoder's decisions will remain in-sync with the decoder.
If it is larger than the up-front maximum, the packet size is kept
 at that maximum, also ensuring sync.
The minimum used now is slightly larger than it used to be, because
 it also includes the bits added for dynalloc boosting.
Such boosting is shut off by the encoder at low rates, and so
 should not cause any serious issues at the rates where we would
 actually run out of room before compute_allocation().
2011-01-09 02:06:53 -05:00

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/* Copyright (c) 2007-2008 CSIRO
Copyright (c) 2007-2009 Xiph.Org Foundation
Written by Jean-Marc Valin */
/*
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
- Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
- Neither the name of the Xiph.org Foundation nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "quant_bands.h"
#include "laplace.h"
#include <math.h>
#include "os_support.h"
#include "arch.h"
#include "mathops.h"
#include "stack_alloc.h"
#ifdef FIXED_POINT
/* Mean energy in each band quantized in Q6 */
static const signed char eMeans[25] = {
103,100, 92, 85, 81,
77, 72, 70, 78, 75,
73, 71, 78, 74, 69,
72, 70, 74, 76, 71,
60, 60, 60, 60, 60
};
#else
/* Mean energy in each band quantized in Q6 and converted back to float */
static const celt_word16 eMeans[25] = {
6.437500f, 6.250000f, 5.750000f, 5.312500f, 5.062500f,
4.812500f, 4.500000f, 4.375000f, 4.875000f, 4.687500f,
4.562500f, 4.437500f, 4.875000f, 4.625000f, 4.312500f,
4.500000f, 4.375000f, 4.625000f, 4.750000f, 4.437500f,
3.750000f, 3.750000f, 3.750000f, 3.750000f, 3.750000f
};
#endif
/* prediction coefficients: 0.9, 0.8, 0.65, 0.5 */
#ifdef FIXED_POINT
static const celt_word16 pred_coef[4] = {29440, 26112, 21248, 16384};
static const celt_word16 beta_coef[4] = {30147, 22282, 12124, 6554};
#else
static const celt_word16 pred_coef[4] = {29440/32768., 26112/32768., 21248/32768., 16384/32768.};
static const celt_word16 beta_coef[4] = {30147/32768., 22282/32768., 12124/32768., 6554/32768.};
#endif
/*Parameters of the Laplace-like probability models used for the coarse energy.
There is one pair of parameters for each frame size, prediction type
(inter/intra), and band number.
The first number of each pair is the probability of 0, and the second is the
decay rate, both in Q8 precision.*/
static const unsigned char e_prob_model[4][2][42] = {
/*120 sample frames.*/
{
/*Inter*/
{
72, 127, 65, 129, 66, 128, 65, 128, 64, 128, 62, 128, 64, 128,
64, 128, 92, 78, 92, 79, 92, 78, 90, 79, 116, 41, 115, 40,
114, 40, 132, 26, 132, 26, 145, 17, 161, 12, 176, 10, 177, 11
},
/*Intra*/
{
24, 179, 48, 138, 54, 135, 54, 132, 53, 134, 56, 133, 55, 132,
55, 132, 61, 114, 70, 96, 74, 88, 75, 88, 87, 74, 89, 66,
91, 67, 100, 59, 108, 50, 120, 40, 122, 37, 97, 43, 78, 50
}
},
/*240 sample frames.*/
{
/*Inter*/
{
83, 78, 84, 81, 88, 75, 86, 74, 87, 71, 90, 73, 93, 74,
93, 74, 109, 40, 114, 36, 117, 34, 117, 34, 143, 17, 145, 18,
146, 19, 162, 12, 165, 10, 178, 7, 189, 6, 190, 8, 177, 9
},
/*Intra*/
{
23, 178, 54, 115, 63, 102, 66, 98, 69, 99, 74, 89, 71, 91,
73, 91, 78, 89, 86, 80, 92, 66, 93, 64, 102, 59, 103, 60,
104, 60, 117, 52, 123, 44, 138, 35, 133, 31, 97, 38, 77, 45
}
},
/*480 sample frames.*/
{
/*Inter*/
{
61, 90, 93, 60, 105, 42, 107, 41, 110, 45, 116, 38, 113, 38,
112, 38, 124, 26, 132, 27, 136, 19, 140, 20, 155, 14, 159, 16,
158, 18, 170, 13, 177, 10, 187, 8, 192, 6, 175, 9, 159, 10
},
/*Intra*/
{
21, 178, 59, 110, 71, 86, 75, 85, 84, 83, 91, 66, 88, 73,
87, 72, 92, 75, 98, 72, 105, 58, 107, 54, 115, 52, 114, 55,
112, 56, 129, 51, 132, 40, 150, 33, 140, 29, 98, 35, 77, 42
}
},
/*960 sample frames.*/
{
/*Inter*/
{
42, 121, 96, 66, 108, 43, 111, 40, 117, 44, 123, 32, 120, 36,
119, 33, 127, 33, 134, 34, 139, 21, 147, 23, 152, 20, 158, 25,
154, 26, 166, 21, 173, 16, 184, 13, 184, 10, 150, 13, 139, 15
},
/*Intra*/
{
22, 178, 63, 114, 74, 82, 84, 83, 92, 82, 103, 62, 96, 72,
96, 67, 101, 73, 107, 72, 113, 55, 118, 52, 125, 52, 118, 52,
117, 55, 135, 49, 137, 39, 157, 32, 145, 29, 97, 33, 77, 40
}
}
};
static const unsigned char small_energy_icdf[3]={2,1,0};
static int intra_decision(const celt_word16 *eBands, celt_word16 *oldEBands, int start, int end, int len, int C)
{
int c, i;
celt_word32 dist = 0;
c=0; do {
for (i=start;i<end;i++)
{
celt_word16 d = SHR16(SUB16(eBands[i+c*len], oldEBands[i+c*len]),2);
dist = MAC16_16(dist, d,d);
}
} while (++c<C);
return SHR32(dist,2*DB_SHIFT-4) > 2*C*(end-start);
}
static void quant_coarse_energy_impl(const CELTMode *m, int start, int end,
const celt_word16 *eBands, celt_word16 *oldEBands,
ec_int32 budget, ec_int32 tell,
const unsigned char *prob_model, celt_word16 *error, ec_enc *enc,
int _C, int LM, int intra, celt_word16 max_decay)
{
const int C = CHANNELS(_C);
int i, c;
celt_word32 prev[2] = {0,0};
celt_word16 coef;
celt_word16 beta;
if (tell+3 <= budget)
ec_enc_bit_logp(enc, intra, 3);
if (intra)
{
coef = 0;
beta = QCONST16(.15f,15);
} else {
beta = beta_coef[LM];
coef = pred_coef[LM];
}
/* Encode at a fixed coarse resolution */
for (i=start;i<end;i++)
{
c=0;
do {
int bits_left;
int qi;
celt_word16 q;
celt_word16 x;
celt_word32 f;
x = eBands[i+c*m->nbEBands];
#ifdef FIXED_POINT
f = SHL32(EXTEND32(x),15) -MULT16_16(coef,oldEBands[i+c*m->nbEBands])-prev[c];
/* Rounding to nearest integer here is really important! */
qi = (f+QCONST32(.5,DB_SHIFT+15))>>(DB_SHIFT+15);
#else
f = x-coef*oldEBands[i+c*m->nbEBands]-prev[c];
/* Rounding to nearest integer here is really important! */
qi = (int)floor(.5f+f);
#endif
/* Prevent the energy from going down too quickly (e.g. for bands
that have just one bin) */
if (qi < 0 && x < oldEBands[i+c*m->nbEBands]-max_decay)
{
qi += (int)SHR16(oldEBands[i+c*m->nbEBands]-max_decay-x, DB_SHIFT);
if (qi > 0)
qi = 0;
}
/* If we don't have enough bits to encode all the energy, just assume
something safe. */
tell = ec_enc_tell(enc, 0);
bits_left = budget-tell-3*C*(end-i);
if (i!=start && bits_left < 30)
{
if (bits_left < 24)
qi = IMIN(1, qi);
if (bits_left < 16)
qi = IMAX(-1, qi);
}
if (budget-tell >= 15)
{
int pi;
pi = 2*IMIN(i,20);
ec_laplace_encode(enc, &qi,
prob_model[pi]<<7, prob_model[pi+1]<<6);
}
else if(budget-tell >= 2)
{
qi = IMAX(-1, IMIN(qi, 1));
ec_enc_icdf(enc, 2*qi^-(qi<0), small_energy_icdf, 2);
}
else if(budget-tell >= 1)
{
qi = IMIN(0, qi);
ec_enc_bit_logp(enc, -qi, 1);
}
else
qi = -1;
error[i+c*m->nbEBands] = PSHR32(f,15) - SHL16(qi,DB_SHIFT);
q = SHL16(qi,DB_SHIFT);
oldEBands[i+c*m->nbEBands] = PSHR32(MULT16_16(coef,oldEBands[i+c*m->nbEBands]) + prev[c] + SHL32(EXTEND32(q),15), 15);
prev[c] = prev[c] + SHL32(EXTEND32(q),15) - MULT16_16(beta,q);
} while (++c < C);
}
}
void quant_coarse_energy(const CELTMode *m, int start, int end, int effEnd,
const celt_word16 *eBands, celt_word16 *oldEBands, ec_uint32 budget,
celt_word16 *error, ec_enc *enc, int _C, int LM, int nbAvailableBytes,
int force_intra, int *delayedIntra, int two_pass)
{
const int C = CHANNELS(_C);
int intra;
celt_word16 max_decay;
VARDECL(celt_word16, oldEBands_intra);
VARDECL(celt_word16, error_intra);
ec_enc enc_start_state;
ec_byte_buffer buf_start_state;
ec_uint32 tell;
SAVE_STACK;
intra = force_intra || (*delayedIntra && nbAvailableBytes > end*C);
if (/*shortBlocks || */intra_decision(eBands, oldEBands, start, effEnd, m->nbEBands, C))
*delayedIntra = 1;
else
*delayedIntra = 0;
tell = ec_enc_tell(enc, 0);
if (tell+3 > budget)
two_pass = intra = 0;
/* Encode the global flags using a simple probability model
(first symbols in the stream) */
#ifdef FIXED_POINT
max_decay = MIN32(QCONST16(16,DB_SHIFT), SHL32(EXTEND32(nbAvailableBytes),DB_SHIFT-3));
#else
max_decay = MIN32(16.f, .125f*nbAvailableBytes);
#endif
enc_start_state = *enc;
buf_start_state = *(enc->buf);
ALLOC(oldEBands_intra, C*m->nbEBands, celt_word16);
ALLOC(error_intra, C*m->nbEBands, celt_word16);
CELT_COPY(oldEBands_intra, oldEBands, C*end);
if (two_pass || intra)
{
quant_coarse_energy_impl(m, start, end, eBands, oldEBands_intra, budget,
tell, e_prob_model[LM][1], error_intra, enc, C, LM, 1, max_decay);
}
if (!intra)
{
ec_enc enc_intra_state;
ec_byte_buffer buf_intra_state;
int tell_intra;
ec_uint32 nstart_bytes;
ec_uint32 nintra_bytes;
VARDECL(unsigned char, intra_bits);
tell_intra = ec_enc_tell(enc, 3);
enc_intra_state = *enc;
buf_intra_state = *(enc->buf);
nstart_bytes = ec_byte_bytes(&buf_start_state);
nintra_bytes = ec_byte_bytes(&buf_intra_state);
ALLOC(intra_bits, nintra_bytes-nstart_bytes, unsigned char);
/* Copy bits from intra bit-stream */
CELT_COPY(intra_bits,
ec_byte_get_buffer(&buf_intra_state) + nstart_bytes,
nintra_bytes - nstart_bytes);
*enc = enc_start_state;
*(enc->buf) = buf_start_state;
quant_coarse_energy_impl(m, start, end, eBands, oldEBands, budget,
tell, e_prob_model[LM][intra], error, enc, C, LM, 0, max_decay);
if (two_pass && ec_enc_tell(enc, 3) > tell_intra)
{
*enc = enc_intra_state;
*(enc->buf) = buf_intra_state;
/* Copy intra bits to bit-stream */
CELT_COPY(ec_byte_get_buffer(&buf_intra_state) + nstart_bytes,
intra_bits, nintra_bytes - nstart_bytes);
CELT_COPY(oldEBands, oldEBands_intra, C*end);
CELT_COPY(error, error_intra, C*end);
}
} else {
CELT_COPY(oldEBands, oldEBands_intra, C*end);
CELT_COPY(error, error_intra, C*end);
}
RESTORE_STACK;
}
void quant_fine_energy(const CELTMode *m, int start, int end, celt_ener *eBands, celt_word16 *oldEBands, celt_word16 *error, int *fine_quant, ec_enc *enc, int _C)
{
int i, c;
const int C = CHANNELS(_C);
/* Encode finer resolution */
for (i=start;i<end;i++)
{
celt_int16 frac = 1<<fine_quant[i];
if (fine_quant[i] <= 0)
continue;
c=0;
do {
int q2;
celt_word16 offset;
#ifdef FIXED_POINT
/* Has to be without rounding */
q2 = (error[i+c*m->nbEBands]+QCONST16(.5f,DB_SHIFT))>>(DB_SHIFT-fine_quant[i]);
#else
q2 = (int)floor((error[i+c*m->nbEBands]+.5f)*frac);
#endif
if (q2 > frac-1)
q2 = frac-1;
if (q2<0)
q2 = 0;
ec_enc_bits(enc, q2, fine_quant[i]);
#ifdef FIXED_POINT
offset = SUB16(SHR32(SHL32(EXTEND32(q2),DB_SHIFT)+QCONST16(.5,DB_SHIFT),fine_quant[i]),QCONST16(.5f,DB_SHIFT));
#else
offset = (q2+.5f)*(1<<(14-fine_quant[i]))*(1.f/16384) - .5f;
#endif
oldEBands[i+c*m->nbEBands] += offset;
error[i+c*m->nbEBands] -= offset;
/*printf ("%f ", error[i] - offset);*/
} while (++c < C);
}
}
void quant_energy_finalise(const CELTMode *m, int start, int end, celt_ener *eBands, celt_word16 *oldEBands, celt_word16 *error, int *fine_quant, int *fine_priority, int bits_left, ec_enc *enc, int _C)
{
int i, prio, c;
const int C = CHANNELS(_C);
/* Use up the remaining bits */
for (prio=0;prio<2;prio++)
{
for (i=start;i<end && bits_left>=C ;i++)
{
if (fine_quant[i] >= 7 || fine_priority[i]!=prio)
continue;
c=0;
do {
int q2;
celt_word16 offset;
q2 = error[i+c*m->nbEBands]<0 ? 0 : 1;
ec_enc_bits(enc, q2, 1);
#ifdef FIXED_POINT
offset = SHR16(SHL16(q2,DB_SHIFT)-QCONST16(.5,DB_SHIFT),fine_quant[i]+1);
#else
offset = (q2-.5f)*(1<<(14-fine_quant[i]-1))*(1.f/16384);
#endif
oldEBands[i+c*m->nbEBands] += offset;
bits_left--;
} while (++c < C);
}
}
}
void unquant_coarse_energy(const CELTMode *m, int start, int end, celt_ener *eBands, celt_word16 *oldEBands, int intra, ec_dec *dec, int _C, int LM)
{
const unsigned char *prob_model = e_prob_model[LM][intra];
int i, c;
celt_word32 prev[2] = {0, 0};
celt_word16 coef;
celt_word16 beta;
const int C = CHANNELS(_C);
ec_int32 budget;
ec_int32 tell;
if (intra)
{
coef = 0;
beta = QCONST16(.15f,15);
} else {
beta = beta_coef[LM];
coef = pred_coef[LM];
}
budget = dec->buf->storage*8;
/* Decode at a fixed coarse resolution */
for (i=start;i<end;i++)
{
c=0;
do {
int qi;
celt_word16 q;
tell = ec_dec_tell(dec, 0);
if(budget-tell>=15)
{
int pi;
pi = 2*IMIN(i,20);
qi = ec_laplace_decode(dec,
prob_model[pi]<<7, prob_model[pi+1]<<6);
}
else if(budget-tell>=2)
{
qi = ec_dec_icdf(dec, small_energy_icdf, 2);
qi = (qi>>1)^-(qi&1);
}
else if(budget-tell>=1)
{
qi = -ec_dec_bit_logp(dec, 1);
}
else
qi = -1;
q = SHL16(qi,DB_SHIFT);
oldEBands[i+c*m->nbEBands] = PSHR32(MULT16_16(coef,oldEBands[i+c*m->nbEBands]) + prev[c] + SHL32(EXTEND32(q),15), 15);
prev[c] = prev[c] + SHL32(EXTEND32(q),15) - MULT16_16(beta,q);
} while (++c < C);
}
}
void unquant_fine_energy(const CELTMode *m, int start, int end, celt_ener *eBands, celt_word16 *oldEBands, int *fine_quant, ec_dec *dec, int _C)
{
int i, c;
const int C = CHANNELS(_C);
/* Decode finer resolution */
for (i=start;i<end;i++)
{
if (fine_quant[i] <= 0)
continue;
c=0;
do {
int q2;
celt_word16 offset;
q2 = ec_dec_bits(dec, fine_quant[i]);
#ifdef FIXED_POINT
offset = SUB16(SHR32(SHL32(EXTEND32(q2),DB_SHIFT)+QCONST16(.5,DB_SHIFT),fine_quant[i]),QCONST16(.5f,DB_SHIFT));
#else
offset = (q2+.5f)*(1<<(14-fine_quant[i]))*(1.f/16384) - .5f;
#endif
oldEBands[i+c*m->nbEBands] += offset;
} while (++c < C);
}
}
void unquant_energy_finalise(const CELTMode *m, int start, int end, celt_ener *eBands, celt_word16 *oldEBands, int *fine_quant, int *fine_priority, int bits_left, ec_dec *dec, int _C)
{
int i, prio, c;
const int C = CHANNELS(_C);
/* Use up the remaining bits */
for (prio=0;prio<2;prio++)
{
for (i=start;i<end && bits_left>=C ;i++)
{
if (fine_quant[i] >= 8 || fine_priority[i]!=prio)
continue;
c=0;
do {
int q2;
celt_word16 offset;
q2 = ec_dec_bits(dec, 1);
#ifdef FIXED_POINT
offset = SHR16(SHL16(q2,DB_SHIFT)-QCONST16(.5,DB_SHIFT),fine_quant[i]+1);
#else
offset = (q2-.5f)*(1<<(14-fine_quant[i]-1))*(1.f/16384);
#endif
oldEBands[i+c*m->nbEBands] += offset;
bits_left--;
} while (++c < C);
}
}
}
void log2Amp(const CELTMode *m, int start, int end,
celt_ener *eBands, celt_word16 *oldEBands, int _C)
{
int c, i;
const int C = CHANNELS(_C);
c=0;
do {
for (i=start;i<m->nbEBands;i++)
{
celt_word16 lg = oldEBands[i+c*m->nbEBands]
+ SHL16((celt_word16)eMeans[i],6);
eBands[i+c*m->nbEBands] = PSHR32(celt_exp2(SHL16(lg,11-DB_SHIFT)),4);
if (oldEBands[i+c*m->nbEBands] < -QCONST16(14.f,DB_SHIFT))
oldEBands[i+c*m->nbEBands] = -QCONST16(14.f,DB_SHIFT);
}
} while (++c < C);
}
void amp2Log2(const CELTMode *m, int effEnd, int end,
celt_ener *bandE, celt_word16 *bandLogE, int _C)
{
int c, i;
const int C = CHANNELS(_C);
c=0;
do {
for (i=0;i<effEnd;i++)
bandLogE[i+c*m->nbEBands] =
celt_log2(MAX32(QCONST32(.001f,14),SHL32(bandE[i+c*m->nbEBands],2)))
- SHL16((celt_word16)eMeans[i],6);
for (i=effEnd;i<end;i++)
bandLogE[c*m->nbEBands+i] = -QCONST16(14.f,DB_SHIFT);
} while (++c < C);
}
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