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Improved quality of small frame sizes at low bitrate.

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Adding a temporal energy floor to prevent extremely small values when there's
only one bin in the band.
This commit is contained in:
Jean-Marc Valin 2010-06-23 15:22:54 -04:00
parent 281c8b7e99
commit a01106587c
3 changed files with 16 additions and 3 deletions
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9
libcelt/celt.c
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@ -717,6 +717,7 @@ int celt_encode_with_ec_float(CELTEncoder * restrict st, const celt_sig * pcm, c
int LM, M;
int tf_select;
celt_int32 vbr_rate=0;
celt_word16 max_decay;
int nbFilledBytes, nbAvailableBytes;
SAVE_STACK;
@ -952,7 +953,13 @@ int celt_encode_with_ec_float(CELTEncoder * restrict st, const celt_sig * pcm, c
/* Bit allocation */
ALLOC(error, C*st->mode->nbEBands, celt_word16);
coarse_needed = quant_coarse_energy(st->mode, st->start, bandLogE, st->oldBandE, nbAvailableBytes*4-8, intra_ener, st->mode->prob, error, enc, C);
#ifdef FIXED_POINT
max_decay = MIN32(QCONST16(16,DB_SHIFT), SHL32(EXTEND32(nbAvailableBytes),DB_SHIFT-3));
#else
max_decay = .125*nbAvailableBytes;
#endif
coarse_needed = quant_coarse_energy(st->mode, st->start, bandLogE, st->oldBandE, nbAvailableBytes*4-8, intra_ener, st->mode->prob, error, enc, C, max_decay);
coarse_needed = ((coarse_needed*3-1)>>3)+1;
if (coarse_needed > nbAvailableBytes)
coarse_needed = nbAvailableBytes;