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Bug 1289668 - Use 64 bits to store FrameStatistics values - r=kamidphish

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Decoders uses 64-bit values to count frames, so we should use the same type
in FrameStatistics.

Because VideoPlaybackQuality can only use 32 bits (as defined in W3C specs),
we need to ensure that imported FrameStatistics numbers can fit in 32 bits,
while keeping their ratios the same.

MozReview-Commit-ID: 3pUTGK0ekGv
This commit is contained in:
Gerald Squelart
2016-07-18 10:51:30 +10:00
parent ba51d3e4a1
commit b76c86e6f7
2 changed files with 29 additions and 14 deletions
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23
dom/html/HTMLVideoElement.cpp
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@@ -31,6 +31,9 @@
#include "mozilla/dom/Performance.h"
#include "mozilla/dom/VideoPlaybackQuality.h"
#include <algorithm>
#include <limits>
NS_IMPL_NS_NEW_HTML_ELEMENT(Video)
namespace mozilla {
@@ -244,10 +247,22 @@ HTMLVideoElement::GetVideoPlaybackQuality()
if (mDecoder) {
FrameStatisticsData stats =
mDecoder->GetFrameStatistics().GetFrameStatisticsData();
static_assert(sizeof(totalFrames) >= sizeof(stats.mParsedFrames),
"possible truncation from FrameStatistics to VideoPlaybackQuality");
totalFrames = stats.mParsedFrames;
droppedFrames = stats.mDroppedFrames;
if (sizeof(totalFrames) >= sizeof(stats.mParsedFrames)) {
totalFrames = stats.mParsedFrames;
droppedFrames = stats.mDroppedFrames;
} else {
auto maxStat = std::max(stats.mParsedFrames, stats.mDroppedFrames);
const auto maxNumber = std::numeric_limits<uint32_t>::max();
if (maxStat <= maxNumber) {
totalFrames = static_cast<uint32_t>(stats.mParsedFrames);
droppedFrames = static_cast<uint32_t>(stats.mDroppedFrames);
} else {
// Too big number(s) -> Resize everything to fit in 32 bits.
double ratio = double(maxNumber) / double(maxStat);
totalFrames = double(stats.mParsedFrames) * ratio;
droppedFrames = double(stats.mDroppedFrames) * ratio;
}
}
corruptedFrames = 0;
}
}