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(*
* Rational numbers
* Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*)
unit rational;
interface
{$IFDEF win32}
uses
windows;
{$endif}
const
{$IFDEF win32}
av__util = 'avutil-49.dll';
{$ELSE}
av__util = 'libavutil.so'; // .0d
{$ENDIF}
type
(*
* Rational number num/den. *)
PAVRational = ^TAVRational;
TAVRational = record
num: integer; ///< numerator
den: integer; ///< denominator
end;
(**
* returns 0 if a==b, 1 if a>b and -1 if a<b.
*)
function av_cmp_q(a: TAVRational; b: TAVRational): integer;
(**
* converts the given AVRational to a double.
*)
function av_q2d(a: TAVRational): double;
(**
* reduce a fraction.
* this is usefull for framerate calculations
* @param max the maximum allowed for dst_nom & dst_den
* @return 1 if exact, 0 otherwise
*)
function av_reduce(dst_nom: pinteger; dst_den: PInteger; nom: int64; den: int64; max: int64): integer;
cdecl; external av__util;
function av_mul_q(b: TAVRational; c: TAVRational): TAVRational;
cdecl; external av__util;
function av_div_q(b: TAVRational; c: TAVRational): TAVRational;
cdecl; external av__util;
function av_add_q(b: TAVRational; c: TAVRational): TAVRational;
cdecl; external av__util;
function av_sub_q(b: TAVRational; c: TAVRational): TAVRational;
cdecl; external av__util;
function av_d2q(d: double; max: integer): TAVRational;
cdecl; external av__util;
implementation
function av_cmp_q (a: TAVRational; b: TAVRational): integer;
var
tmp: int64;
begin
tmp := a.num * b.den - b.num * a.den;
if tmp = 0 then
Result := (tmp shr 63) or 1
else
Result := 0;
end;
function av_q2d(a: TAVRational): double;
begin
Result := a.num / a.den;
end;
end.
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