From abfe5a4a7537f7ce9a2694cdac76662f12b3b978 Mon Sep 17 00:00:00 2001 From: Justin Ruggles Date: Fri, 9 Mar 2007 03:17:43 +0000 Subject: simplify AC-3 bit allocation Originally committed as revision 8302 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/ac3enc.c | 101 +++++++++++++--------------------------------------- 1 file changed, 24 insertions(+), 77 deletions(-) (limited to 'libavcodec/ac3enc.c') diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c index 8fc46a21a6..bb48047da6 100644 --- a/libavcodec/ac3enc.c +++ b/libavcodec/ac3enc.c @@ -83,13 +83,12 @@ static inline int16_t fix15(float a) return v; } -static inline int calc_lowcomp1(int a, int b0, int b1) +static inline int calc_lowcomp1(int a, int b0, int b1, int c) { if ((b0 + 256) == b1) { - a = 384; + a = c; } else if (b0 > b1) { - a = a - 64; - if (a < 0) a=0; + a = FFMAX(a - 64, 0); } return a; } @@ -97,24 +96,12 @@ static inline int calc_lowcomp1(int a, int b0, int b1) static inline int calc_lowcomp(int a, int b0, int b1, int bin) { if (bin < 7) { - if ((b0 + 256) == b1) { - a = 384; - } else if (b0 > b1) { - a = a - 64; - if (a < 0) a=0; - } + return calc_lowcomp1(a, b0, b1, 384); } else if (bin < 20) { - if ((b0 + 256) == b1) { - a = 320; - } else if (b0 > b1) { - a= a - 64; - if (a < 0) a=0; - } + return calc_lowcomp1(a, b0, b1, 320); } else { - a = a - 128; - if (a < 0) a=0; + return FFMAX(a - 128, 0); } - return a; } /* AC3 bit allocation. The algorithm is the one described in the AC3 @@ -125,7 +112,7 @@ void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap, int deltbae,int deltnseg, uint8_t *deltoffst, uint8_t *deltlen, uint8_t *deltba) { - int bin,i,j,k,end1,v,v1,bndstrt,bndend,lowcomp,begin; + int bin,i,j,k,end1,v,bndstrt,bndend,lowcomp,begin; int fastleak,slowleak,address,tmp; int16_t psd[256]; /* scaled exponents */ int16_t bndpsd[50]; /* interpolated exponents */ @@ -143,22 +130,11 @@ void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap, do { v=psd[j]; j++; - end1=bndtab[k+1]; - if (end1 > end) end1=end; + end1 = FFMIN(bndtab[k+1], end); for(i=j;i= 0) { - adr=c >> 1; - if (adr > 255) adr=255; - v=v + latab[adr]; - } else { - adr=(-c) >> 1; - if (adr > 255) adr=255; - v=v1 + latab[adr]; - } + int adr = FFMIN(FFABS(v - psd[j]) >> 1, 255); + v = FFMAX(v, psd[j]) + latab[adr]; j++; } bndpsd[k]=v; @@ -171,14 +147,14 @@ void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap, if (bndstrt == 0) { lowcomp = 0; - lowcomp = calc_lowcomp1(lowcomp, bndpsd[0], bndpsd[1]); + lowcomp = calc_lowcomp1(lowcomp, bndpsd[0], bndpsd[1], 384); excite[0] = bndpsd[0] - fgain - lowcomp; - lowcomp = calc_lowcomp1(lowcomp, bndpsd[1], bndpsd[2]); + lowcomp = calc_lowcomp1(lowcomp, bndpsd[1], bndpsd[2], 384); excite[1] = bndpsd[1] - fgain - lowcomp; begin = 7; for (bin = 2; bin < 7; bin++) { if (!(is_lfe && bin == 6)) - lowcomp = calc_lowcomp1(lowcomp, bndpsd[bin], bndpsd[bin+1]); + lowcomp = calc_lowcomp1(lowcomp, bndpsd[bin], bndpsd[bin+1], 384); fastleak = bndpsd[bin] - fgain; slowleak = bndpsd[bin] - s->sgain; excite[bin] = fastleak - lowcomp; @@ -197,18 +173,9 @@ void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap, if (!(is_lfe && bin == 6)) lowcomp = calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin+1], bin); - fastleak -= s->fdecay; - v = bndpsd[bin] - fgain; - if (fastleak < v) fastleak = v; - - slowleak -= s->sdecay; - v = bndpsd[bin] - s->sgain; - if (slowleak < v) slowleak = v; - - v=fastleak - lowcomp; - if (slowleak > v) v=slowleak; - - excite[bin] = v; + fastleak = FFMAX(fastleak - s->fdecay, bndpsd[bin] - fgain); + slowleak = FFMAX(slowleak - s->sdecay, bndpsd[bin] - s->sgain); + excite[bin] = FFMAX(fastleak - lowcomp, slowleak); } begin = 22; } else { @@ -220,29 +187,19 @@ void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap, } for (bin = begin; bin < bndend; bin++) { - fastleak -= s->fdecay; - v = bndpsd[bin] - fgain; - if (fastleak < v) fastleak = v; - slowleak -= s->sdecay; - v = bndpsd[bin] - s->sgain; - if (slowleak < v) slowleak = v; - - v=fastleak; - if (slowleak > v) v = slowleak; - excite[bin] = v; + fastleak = FFMAX(fastleak - s->fdecay, bndpsd[bin] - fgain); + slowleak = FFMAX(slowleak - s->sdecay, bndpsd[bin] - s->sgain); + excite[bin] = FFMAX(fastleak, slowleak); } /* compute masking curve */ for (bin = bndstrt; bin < bndend; bin++) { - v1 = excite[bin]; tmp = s->dbknee - bndpsd[bin]; if (tmp > 0) { - v1 += tmp >> 2; + excite[bin] += tmp >> 2; } - v=hth[bin >> s->halfratecod][s->fscod]; - if (v1 > v) v=v1; - mask[bin] = v; + mask[bin] = FFMAX(hth[bin >> s->halfratecod][s->fscod], excite[bin]); } /* delta bit allocation */ @@ -269,20 +226,10 @@ void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap, i = start; j = masktab[start]; do { - v=mask[j]; - v -= snroffset; - v -= s->floor; - if (v < 0) v = 0; - v &= 0x1fe0; - v += s->floor; - - end1=bndtab[j] + bndsz[j]; - if (end1 > end) end1=end; - + v = (FFMAX(mask[j] - snroffset - s->floor, 0) & 0x1FE0) + s->floor; + end1 = FFMIN(bndtab[j] + bndsz[j], end); for (k = i; k < end1; k++) { - address = (psd[i] - v) >> 5; - if (address < 0) address=0; - else if (address > 63) address=63; + address = av_clip((psd[i] - v) >> 5, 0, 63); bap[i] = baptab[address]; i++; } -- cgit v1.2.3