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ac3enc: split mantissa bit counting into a separate function.

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No speed difference. This is to allow for more flexible bit counting.
This commit is contained in:
Justin Ruggles 2011-05-26 12:31:31 -04:00
parent 7743865ffc
commit 1323828a0f
1 changed files with 31 additions and 18 deletions
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49
libavcodec/ac3enc.c
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@ -1491,22 +1491,12 @@ static void reset_block_bap(AC3EncodeContext *s)
} }
/** static int count_mantissa_bits(AC3EncodeContext *s)
* Run the bit allocation with a given SNR offset.
* This calculates the bit allocation pointers that will be used to determine
* the quantization of each mantissa.
* @return the number of bits needed for mantissas if the given SNR offset is
* is used.
*/
static int bit_alloc(AC3EncodeContext *s, int snr_offset)
{ {
int blk, ch; int blk, ch;
int mantissa_bits; int mantissa_bits;
int mant_cnt[5]; int mant_cnt[5];
snr_offset = (snr_offset - 240) << 2;
reset_block_bap(s);
mantissa_bits = 0; mantissa_bits = 0;
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) { for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
AC3Block *block = &s->blocks[blk]; AC3Block *block = &s->blocks[blk];
@ -1524,7 +1514,36 @@ static int bit_alloc(AC3EncodeContext *s, int snr_offset)
ch = CPL_CH; ch = CPL_CH;
got_cpl = 1; got_cpl = 1;
} }
mantissa_bits += s->ac3dsp.compute_mantissa_size(mant_cnt,
s->ref_bap[ch][blk]+s->start_freq[ch],
block->end_freq[ch]-s->start_freq[ch]);
if (ch == CPL_CH)
ch = ch0;
}
mantissa_bits += compute_mantissa_size_final(mant_cnt);
}
return mantissa_bits;
}
/**
* Run the bit allocation with a given SNR offset.
* This calculates the bit allocation pointers that will be used to determine
* the quantization of each mantissa.
* @return the number of bits needed for mantissas if the given SNR offset is
* is used.
*/
static int bit_alloc(AC3EncodeContext *s, int snr_offset)
{
int blk, ch;
snr_offset = (snr_offset - 240) << 2;
reset_block_bap(s);
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
AC3Block *block = &s->blocks[blk];
for (ch = !block->cpl_in_use; ch <= s->channels; ch++) {
/* Currently the only bit allocation parameters which vary across /* Currently the only bit allocation parameters which vary across
blocks within a frame are the exponent values. We can take blocks within a frame are the exponent values. We can take
advantage of that by reusing the bit allocation pointers advantage of that by reusing the bit allocation pointers
@ -1535,15 +1554,9 @@ static int bit_alloc(AC3EncodeContext *s, int snr_offset)
snr_offset, s->bit_alloc.floor, snr_offset, s->bit_alloc.floor,
ff_ac3_bap_tab, s->ref_bap[ch][blk]); ff_ac3_bap_tab, s->ref_bap[ch][blk]);
} }
mantissa_bits += s->ac3dsp.compute_mantissa_size(mant_cnt,
s->ref_bap[ch][blk]+s->start_freq[ch],
block->end_freq[ch]-s->start_freq[ch]);
if (ch == CPL_CH)
ch = ch0;
} }
mantissa_bits += compute_mantissa_size_final(mant_cnt);
} }
return mantissa_bits; return count_mantissa_bits(s);
} }