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avcodec/on2avc: fix regression on icc since 5495c7f 

Should fix the regression, and also speeds up table generation.
Tables tested on GNU/Linux+clang: they are identical to the ones prior
to 5495c7f. ff_exp10 caused one slight change in one entry, 50000 became
50001 due to somewhat incorrect rounding.

Untested on ICC; passes FATE on GNU/Linux+gcc.

Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
This commit is contained in:
Ganesh Ajjanagadde 2015-12-26 16:53:12 -08:00
parent e70d56b8ad
commit 71af38954b
1 changed files with 32 additions and 3 deletions
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35
libavcodec/on2avc.c
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@ -912,7 +912,23 @@ static av_cold void on2avc_free_vlcs(On2AVCContext *c)
static av_cold int on2avc_decode_init(AVCodecContext *avctx)
{
On2AVCContext *c = avctx->priv_data;
int i;
int i, ph;
/* 10^(i*0.1) for 0 <= i < 10 */
/* TODO: possibly statically allocate scale_tab; this may help with FATE
* and reproducibility if the binary size is not impacted much */
static const double exp10_lut[] = {
1,
1.2589254117941673,
1.5848931924611136,
1.9952623149688795,
2.5118864315095806,
3.1622776601683795,
3.9810717055349727,
5.0118723362727229,
6.3095734448019334,
7.9432823472428158,
};
int64_t exp10_base = 10;
if (avctx->channels > 2U) {
avpriv_request_sample(avctx, "Decoding more than 2 channels");
@ -934,10 +950,23 @@ static av_cold int on2avc_decode_init(AVCodecContext *avctx)
av_log(avctx, AV_LOG_WARNING,
"Stereo mode support is not good, patch is welcome\n");
for (i = 0; i < 20; i++)
/* Fast and more accurate way of doing for (i = 0; i < 20; i++)
c->scale_tab[i] = ceil(ff_exp10(i * 0.1) * 16) / 32;
for (; i < 128; i++)
c->scale_tab[i] = ceil(ff_exp10(i * 0.1) * 0.5);
c->scale_tab[i] = ceil(ff_exp10(i * 0.1) * 0.5); */
for (i = 0; i < 10; i++) {
c->scale_tab[i] = ceil(exp10_lut[i] * 16) / 32;
c->scale_tab[i+10] = ceil(exp10_lut[i] * 160) / 32;
}
for (i = 20, ph = 0; i < 128; i++, ph++) {
if (i % 10 == 0) {
exp10_base *= 10;
ph = 0;
}
c->scale_tab[i] = ceil(exp10_base * exp10_lut[ph] * 0.5);
}
if (avctx->sample_rate < 32000 || avctx->channels == 1)
memcpy(c->long_win, ff_on2avc_window_long_24000,