llMulDiv function
[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
The llMulDiv function implements the formula ((a*b)+rnd)/c where each term is a 64-bit value.
Time stamps and seek times are 64-bit values, so this function is useful for performing conversions on 32-bit systems. For example, the formula for bytes-per-second is
(Number of Bytes * Reference Time) / 10,000,000
which can be calculated as llMulDiv(nBytes, rtTime, 10000000, 0). Use the rnd parameter as a rounding factor.
Syntax
LONGLONG WINAPI Int64x32Div32(
LONGLONG a,
LONGLONG b,
LONGLONG c,
LONGLONG rnd
);
Parameters
-
a
-
Multiplicand.
-
b
-
Multiplier.
-
c
-
Divisor.
-
rnd
-
Rounding factor.
Return value
Returns either the (a * b + rnd)/c calculation or one of the following values.
| Return code | Description |
|---|---|
|
Overflow occurred because the result is too large (positive). |
|
Overflow occurred because the result is too large (negative). |
Remarks
Rounding on the division is toward zero. Division by zero is counted as an overflow condition.
Requirements
| Requirement | Value |
|---|---|
| Header |
|
| Library |
|
See also