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Making VBR slightly exceed the budget rather than fail

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This commit is contained in:
Jean-Marc Valin 2010-12-03 15:20:11 -05:00
parent 30165bbae0
commit a4badac92e
1 changed files with 7 additions and 4 deletions
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11
libcelt/celt.c
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@ -977,11 +977,11 @@ int celt_encode_with_ec_float(CELTEncoder * restrict st, const celt_sig * pcm, i
if (st->vbr_rate_norm>0) if (st->vbr_rate_norm>0)
{ {
celt_word16 alpha; celt_word16 alpha;
celt_int32 delta; celt_int32 delta, tell;
/* The target rate in 8th bits per frame */ /* The target rate in 8th bits per frame */
celt_int32 vbr_rate; celt_int32 vbr_rate;
celt_int32 target; celt_int32 target;
celt_int32 vbr_bound, max_allowed; celt_int32 vbr_bound, max_allowed, min_allowed;
target = vbr_rate = M*st->vbr_rate_norm; target = vbr_rate = M*st->vbr_rate_norm;
@ -996,19 +996,22 @@ int celt_encode_with_ec_float(CELTEncoder * restrict st, const celt_sig * pcm, i
else if (M > 1) else if (M > 1)
target-=(target+14)/28; target-=(target+14)/28;
tell = ec_enc_tell(enc, BITRES);
/* The current offset is removed from the target and the space used /* The current offset is removed from the target and the space used
so far is added*/ so far is added*/
target=target+ec_enc_tell(enc, BITRES); target=target+tell;
/* By how much did we "miss" the target on that frame */ /* By how much did we "miss" the target on that frame */
delta = target - vbr_rate; delta = target - vbr_rate;
/* Computes the max bit-rate allowed in VBR more to avoid violating the target rate and buffering */ /* Computes the max bit-rate allowed in VBR more to avoid violating the target rate and buffering */
vbr_bound = vbr_rate; vbr_bound = vbr_rate;
max_allowed = IMIN(vbr_rate+vbr_bound-st->vbr_reservoir>>(BITRES+3),nbAvailableBytes); max_allowed = IMIN(vbr_rate+vbr_bound-st->vbr_reservoir>>(BITRES+3),nbAvailableBytes);
min_allowed = (tell>>(BITRES+3)) + 2 - nbFilledBytes;
/* In VBR mode the frame size must not be reduced so much that it would result in the encoder running out of bits */ /* In VBR mode the frame size must not be reduced so much that it would result in the encoder running out of bits */
nbAvailableBytes = target+(1<<(BITRES+2))>>(BITRES+3); nbAvailableBytes = target+(1<<(BITRES+2))>>(BITRES+3);
nbAvailableBytes=IMAX(16,IMIN(max_allowed,nbAvailableBytes)); nbAvailableBytes=IMAX(min_allowed,IMIN(max_allowed,nbAvailableBytes));
target=nbAvailableBytes<<(BITRES+3); target=nbAvailableBytes<<(BITRES+3);
if (st->vbr_count < 970) if (st->vbr_count < 970)