Well, Thank you Anthony. 3 questions In summary,
1) in
if (x < rlen) {
z += (int32_t) *(fp + x);
Any difference if change the "+=" to "=" since z is 0? It just confused me.
2) If n1 = 32768, n2 = 32766, after use MACRO
switch_normalize_to_16bit(n1)
switch_normalize_to_16bit(n2)
the result will be:
n1 = 32767/2 = 16383
n2 = 32766
is that the expected result?
3) Is there any chance rlen and wlen both > 0?
On Apr 6, 2009, at 11:16 PM, Anthony Minessale wrote:
what ?
I don't know what your question is.
On Mon, Apr 6, 2009 at 9:35 AM, seven du
<seven@idapted.com> wrote:
Hi, can someone explain this to me?
In switch_core_media_bug.c, around line 173:
for (x = 0; x < blen; x++) {
int32_t z = 0;
if (x < rlen) {
z += (int32_t) *(fp + x); //what's difference here with z =
(int32_t) *(fp + x) ?
}
if (x < wlen) {
z += (int32_t) *(dp + x);
}
switch_normalize_to_16bit(z);
*(fp + x) = (int16_t) z / 2;
}
And for switch_normalize_to_16bit, according to switch_utils.h,
#define SWITCH_SMAX 32767
#define SWITCH_SMIN -32768
#define switch_normalize_to_16bit(n) if (n > SWITCH_SMAX) n =
SWITCH_SMAX / 2; else if (n < SWITCH_SMIN) n = SWITCH_SMIN / 2;
Then
switch_normalize_to_16bit( 32768 ), z = 32767/2, and (int16_t) z / 2 =
32767/4
switch_normalize_to_16bit( 32766) , z = 32766, and (int16_t) z / 2 =
32766/2
Does that make sense? I guess it should be like this:
#define switch_normalize_to_16bit(n) if (n > SWITCH_SMAX) n =
SWITCH_SMAX / 2; else if (n < SWITCH_SMIN) n = SWITCH_SMIN / 2; else n
= n / 2;
switch_normalize_to_16bit(z);
*(fp + x) = (int16_t) z;
Thank you.
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