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Implemented "raw bits"

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Making it so all the information encoded directly with ec_enc_bits() gets
stored at the end of the stream, without going through the range coder. This
should be both faster and reduce the effects of bit errors.

Conflicts:

	tests/ectest.c
This commit is contained in:
Jean-Marc Valin 2009-06-17 23:23:46 -04:00
parent 8d940a664e
commit c08be4485b
9 changed files with 101 additions and 19 deletions
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22
libcelt/rangedec.c
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@ -141,6 +141,9 @@ void ec_dec_init(ec_dec *_this,ec_byte_buffer *_buf){
_this->dif=_this->rng-(_this->rem>>EC_SYM_BITS-EC_CODE_EXTRA);
/*Normalize the interval.*/
ec_dec_normalize(_this);
/*_this->end_byte=ec_byte_look_at_end(_this->buf);*/
_this->end_bits_left=0;
_this->nb_end_bits=0;
}
@ -152,12 +155,29 @@ unsigned ec_decode(ec_dec *_this,unsigned _ft){
}
unsigned ec_decode_bin(ec_dec *_this,unsigned bits){
#if 0
unsigned s;
ec_uint32 ft;
ft = (ec_uint32)1<<bits;
_this->nrm=_this->rng>>bits;
s=(unsigned)((_this->dif-1)/_this->nrm);
return ft-EC_MINI(s+1,ft);
#else
unsigned value=0;
int count=0;
_this->nb_end_bits += bits;
while (bits>=_this->end_bits_left)
{
value |= _this->end_byte>>(8-_this->end_bits_left)<<count;
count += _this->end_bits_left;
bits -= _this->end_bits_left;
_this->end_byte=ec_byte_look_at_end(_this->buf);
_this->end_bits_left = 8;
}
value |= ((_this->end_byte>>(8-_this->end_bits_left))&((1<<bits)-1))<<count;
_this->end_bits_left -= bits;
return value;
#endif
}
void ec_dec_update(ec_dec *_this,unsigned _fl,unsigned _fh,unsigned _ft){
@ -177,7 +197,7 @@ long ec_dec_tell(ec_dec *_this,int _b){
/*To handle the non-integral number of bits still left in the decoder state,
we compute the number of bits of low that must be encoded to ensure that
the value is inside the range for any possible subsequent bits.*/
nbits+=EC_CODE_BITS+1;
nbits+=EC_CODE_BITS+1+_this->nb_end_bits;
nbits<<=_b;
l=EC_ILOG(_this->rng);
r=_this->rng>>l-16;