gecko-dev/content/media/VideoUtils.cpp
2012-05-21 12:12:37 +01:00

41 lines
1.2 KiB
C++

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "VideoUtils.h"
#include "nsMathUtils.h"
#include "prtypes.h"
#include "mozilla/StandardInteger.h"
// Converts from number of audio frames to microseconds, given the specified
// audio rate.
CheckedInt64 FramesToUsecs(PRInt64 aFrames, PRUint32 aRate) {
return (CheckedInt64(aFrames) * USECS_PER_S) / aRate;
}
// Converts from microseconds to number of audio frames, given the specified
// audio rate.
CheckedInt64 UsecsToFrames(PRInt64 aUsecs, PRUint32 aRate) {
return (CheckedInt64(aUsecs) * aRate) / USECS_PER_S;
}
static PRInt32 ConditionDimension(float aValue)
{
// This will exclude NaNs and too-big values.
if (aValue > 1.0 && aValue <= PR_INT32_MAX)
return PRInt32(NS_round(aValue));
return 0;
}
void ScaleDisplayByAspectRatio(nsIntSize& aDisplay, float aAspectRatio)
{
if (aAspectRatio > 1.0) {
// Increase the intrinsic width
aDisplay.width = ConditionDimension(aAspectRatio * aDisplay.width);
} else {
// Increase the intrinsic height
aDisplay.height = ConditionDimension(aDisplay.height / aAspectRatio);
}
}