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make exponent decoding consistent (prepare for merging coupling and lfe code with normal channel code). 

Originally committed as revision 9904 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2007-08-04 13:26:46 +00:00
parent 0221ae8ca8
commit 0bff58a59a
1 changed files with 14 additions and 11 deletions
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25
libavcodec/ac3dec.c
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@ -697,12 +697,11 @@ static int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk)
{
int nfchans = ctx->nfchans;
int acmod = ctx->acmod;
int i, bnd, seg, grpsize, ch;
int i, bnd, seg, ch;
GetBitContext *gb = &ctx->gb;
int bit_alloc_flags = 0;
int8_t *dexps;
int mstrcplco, cplcoexp, cplcomant;
int chbwcod, ngrps, cplabsexp, skipl;
int chbwcod, skipl;
for (i = 0; i < nfchans; i++) /*block switch flag */
ctx->blksw[i] = get_bits1(gb);
@ -827,28 +826,32 @@ static int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk)
}
if (ctx->cplexpstr != EXP_REUSE) {/* coupling exponents */
int grpsize, ngrps, absexp;
bit_alloc_flags = 64;
cplabsexp = get_bits(gb, 4) << 1;
ngrps = (ctx->cplendmant - ctx->cplstrtmant) / (3 << (ctx->cplexpstr - 1));
decode_exponents(gb, ctx->cplexpstr, ngrps, cplabsexp, ctx->dcplexps + ctx->cplstrtmant);
grpsize = 3 << (ctx->cplexpstr - 1);
ngrps = (ctx->cplendmant - ctx->cplstrtmant) / grpsize;
absexp = get_bits(gb, 4) << 1;
decode_exponents(gb, ctx->cplexpstr, ngrps, absexp, &ctx->dcplexps[ctx->cplstrtmant]);
}
for (i = 0; i < nfchans; i++) { /* fbw channel exponents */
if (ctx->chexpstr[i] != EXP_REUSE) {
int grpsize, ngrps, absexp;
bit_alloc_flags |= 1 << i;
grpsize = 3 << (ctx->chexpstr[i] - 1);
ngrps = (ctx->endmant[i] + grpsize - 4) / grpsize;
dexps = ctx->dexps[i];
dexps[0] = get_bits(gb, 4);
decode_exponents(gb, ctx->chexpstr[i], ngrps, dexps[0], dexps + 1);
absexp = ctx->dexps[i][0] = get_bits(gb, 4);
decode_exponents(gb, ctx->chexpstr[i], ngrps, absexp, &ctx->dexps[i][1]);
skip_bits(gb, 2); /* skip gainrng */
}
}
if (ctx->lfeexpstr != EXP_REUSE) { /* lfe exponents */
int ngrps, absexp;
bit_alloc_flags |= 32;
ctx->dlfeexps[0] = get_bits(gb, 4);
decode_exponents(gb, ctx->lfeexpstr, 2, ctx->dlfeexps[0], ctx->dlfeexps + 1);
ngrps = 2;
absexp = ctx->dlfeexps[0] = get_bits(gb, 4);
decode_exponents(gb, ctx->lfeexpstr, ngrps, absexp, &ctx->dlfeexps[1]);
}
if (get_bits1(gb)) { /* bit allocation information */