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aacdec: Use a LUT to generate CCE scale.

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Originally committed as revision 24224 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Alex Converse 2010-07-12 21:35:43 +00:00
parent f07c9895e0
commit 93c6ff6c8c
1 changed files with 8 additions and 1 deletions
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9
libavcodec/aacdec.c
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@ -1454,6 +1454,13 @@ static int decode_cpe(AACContext *ac, GetBitContext *gb, ChannelElement *cpe)
return 0; return 0;
} }
static const float cce_scale[] = {
1.09050773266525765921, //2^(1/8)
1.18920711500272106672, //2^(1/4)
M_SQRT2,
2,
};
/** /**
* Decode coupling_channel_element; reference: table 4.8. * Decode coupling_channel_element; reference: table 4.8.
* *
@ -1484,7 +1491,7 @@ static int decode_cce(AACContext *ac, GetBitContext *gb, ChannelElement *che)
coup->coupling_point += get_bits1(gb) || (coup->coupling_point >> 1); coup->coupling_point += get_bits1(gb) || (coup->coupling_point >> 1);
sign = get_bits(gb, 1); sign = get_bits(gb, 1);
scale = pow(2., pow(2., (int)get_bits(gb, 2) - 3)); scale = cce_scale[get_bits(gb, 2)];
if ((ret = decode_ics(ac, sce, gb, 0, 0))) if ((ret = decode_ics(ac, sce, gb, 0, 0)))
return ret; return ret;