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am 67c7a4ae: Merge "Fix off-by-two and other bugs in the visualization code. b/3137511" into gingerbread

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This commit is contained in:
Marco Nelissen
2010-10-27 11:08:14 -07:00
committed by Android Git Automerger
parent 222f489fc0 67c7a4ae2e
commit cd08ada7f1
1 changed files with 12 additions and 9 deletions
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21
media/libeffects/visualizer/EffectVisualizer.cpp
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@ -243,19 +243,22 @@ extern "C" int Visualizer_process(
// derive capture scaling factor from peak value in current buffer
// this gives more interesting captures for display.
int32_t shift = 32;
for (size_t i = 0; i < inBuffer->frameCount; i++) {
int len = inBuffer->frameCount * 2;
for (size_t i = 0; i < len; i++) {
int32_t smp = inBuffer->s16[i];
if (smp < 0) smp = -smp;
if (smp < 0) smp = -smp - 1; // take care to keep the max negative in range
int32_t clz = __builtin_clz(smp);
if (shift > clz) shift = clz;
}
// never scale by less than 8 to avoid returning unaltered PCM signal.
// add one to combine the division by 2 needed after summing left and right channels below
if (20 > shift) {
shift = (31 - 8 + 1) - shift;
} else {
shift = (3 + 1);
// A maximum amplitude signal will have 17 leading zeros, which we want to
// translate to a shift of 8 (for converting 16 bit to 8 bit)
shift = 25 - shift;
// Never scale by less than 8 to avoid returning unaltered PCM signal.
if (shift < 3) {
shift = 3;
}
// add one to combine the division by 2 needed after summing left and right channels below
shift++;
uint32_t captIdx;
uint32_t inIdx;
@ -264,7 +267,7 @@ extern "C" int Visualizer_process(
inIdx < inBuffer->frameCount && captIdx < pContext->mCaptureSize;
inIdx++, captIdx++) {
int32_t smp = inBuffer->s16[2 * inIdx] + inBuffer->s16[2 * inIdx + 1];
smp = (smp + (1 << (shift - 1))) >> shift;
smp = smp >> shift;
buf[captIdx] = ((uint8_t)smp)^0x80;
}
pContext->mCaptureIdx = captIdx;