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Code Issues Releases Activity

Remove log2() usage.

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Originally committed as revision 7063 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Benjamin Larsson 2006-11-14 18:54:42 +00:00
parent 0d666a47a7
commit 521fe1d2da
1 changed files with 4 additions and 7 deletions
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11
libavcodec/imc.c
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@ -80,7 +80,6 @@ typedef struct {
float sqrt_tab[30]; float sqrt_tab[30];
GetBitContext gb; GetBitContext gb;
VLC huffman_vlc[4][4]; VLC huffman_vlc[4][4];
float flcf1, flcf2;
int decoder_reset; int decoder_reset;
float one_div_log2; float one_div_log2;
@ -125,8 +124,6 @@ static int imc_decode_init(AVCodecContext * avctx)
q->last_fft_im[i] = 0; q->last_fft_im[i] = 0;
} }
q->flcf1 = log2(10) * 0.05703125;
q->flcf2 = log2(10) * 0.25;
/* Generate a square root table */ /* Generate a square root table */
@ -236,8 +233,8 @@ static void imc_decode_level_coefficients(IMCContext* q, int* levlCoeffBuf, floa
float tmp, tmp2; float tmp, tmp2;
//maybe some frequency division thingy //maybe some frequency division thingy
flcoeffs1[0] = 20000.0 / pow (2, levlCoeffBuf[0] * q->flcf1); flcoeffs1[0] = 20000.0 / pow (2, levlCoeffBuf[0] * 0.18945); // 0.18945 = log2(10) * 0.05703125
flcoeffs2[0] = log2(flcoeffs1[0]); flcoeffs2[0] = log(flcoeffs1[0])/log(2);
tmp = flcoeffs1[0]; tmp = flcoeffs1[0];
tmp2 = flcoeffs2[0]; tmp2 = flcoeffs2[0];
@ -255,7 +252,7 @@ static void imc_decode_level_coefficients(IMCContext* q, int* levlCoeffBuf, floa
level -=16; level -=16;
tmp *= imc_exp_tab[15 + level]; tmp *= imc_exp_tab[15 + level];
tmp2 += q->flcf2 * level; tmp2 += 0.83048 * level; // 0.83048 = log2(10) * 0.25
flcoeffs1[i] = tmp; flcoeffs1[i] = tmp;
flcoeffs2[i] = tmp2; flcoeffs2[i] = tmp2;
} }
@ -273,7 +270,7 @@ static void imc_decode_level_coefficients2(IMCContext* q, int* levlCoeffBuf, flo
flcoeffs1[i] = 0; flcoeffs1[i] = 0;
if(levlCoeffBuf[i] < 16) { if(levlCoeffBuf[i] < 16) {
flcoeffs1[i] = imc_exp_tab2[levlCoeffBuf[i]] * old_floor[i]; flcoeffs1[i] = imc_exp_tab2[levlCoeffBuf[i]] * old_floor[i];
flcoeffs2[i] = (levlCoeffBuf[i]-7) * q->flcf2 + flcoeffs2[i]; flcoeffs2[i] = (levlCoeffBuf[i]-7) * 0.83048 + flcoeffs2[i]; // 0.83048 = log2(10) * 0.25
} else { } else {
flcoeffs1[i] = old_floor[i]; flcoeffs1[i] = old_floor[i];
} }