gecko-dev/content/media/VideoUtils.cpp

91 lines
3.0 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 "MediaResource.h"
#include "nsTimeRanges.h"
#include "nsMathUtils.h"
#include "mozilla/StandardInteger.h"
// Converts from number of audio frames to microseconds, given the specified
// audio rate.
CheckedInt64 FramesToUsecs(int64_t aFrames, uint32_t aRate) {
return (CheckedInt64(aFrames) * USECS_PER_S) / aRate;
}
// Converts from microseconds to number of audio frames, given the specified
// audio rate.
CheckedInt64 UsecsToFrames(int64_t aUsecs, uint32_t aRate) {
return (CheckedInt64(aUsecs) * aRate) / USECS_PER_S;
}
static int32_t ConditionDimension(float aValue)
{
// This will exclude NaNs and too-big values.
if (aValue > 1.0 && aValue <= INT32_MAX)
return int32_t(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);
}
}
static int64_t BytesToTime(int64_t offset, int64_t length, int64_t durationUs) {
NS_ASSERTION(length > 0, "Must have positive length");
double r = double(offset) / double(length);
if (r > 1.0)
r = 1.0;
return int64_t(double(durationUs) * r);
}
void GetEstimatedBufferedTimeRanges(mozilla::MediaResource* aStream,
int64_t aDurationUsecs,
nsTimeRanges* aOutBuffered)
{
// Nothing to cache if the media takes 0us to play.
if (aDurationUsecs <= 0 || !aStream || !aOutBuffered)
return;
// Special case completely cached files. This also handles local files.
if (aStream->IsDataCachedToEndOfResource(0)) {
aOutBuffered->Add(0, double(aDurationUsecs) / USECS_PER_S);
return;
}
int64_t totalBytes = aStream->GetLength();
// If we can't determine the total size, pretend that we have nothing
// buffered. This will put us in a state of eternally-low-on-undecoded-data
// which is not great, but about the best we can do.
if (totalBytes <= 0)
return;
int64_t startOffset = aStream->GetNextCachedData(0);
while (startOffset >= 0) {
int64_t endOffset = aStream->GetCachedDataEnd(startOffset);
// Bytes [startOffset..endOffset] are cached.
NS_ASSERTION(startOffset >= 0, "Integer underflow in GetBuffered");
NS_ASSERTION(endOffset >= 0, "Integer underflow in GetBuffered");
int64_t startUs = BytesToTime(startOffset, totalBytes, aDurationUsecs);
int64_t endUs = BytesToTime(endOffset, totalBytes, aDurationUsecs);
if (startUs != endUs) {
aOutBuffered->Add(double(startUs) / USECS_PER_S,
double(endUs) / USECS_PER_S);
}
startOffset = aStream->GetNextCachedData(endOffset);
}
return;
}