content/media/VideoUtils.cpp

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 #include "VideoUtils.h"
   6 #include "MediaResource.h"
   7 #include "mozilla/dom/TimeRanges.h"
   8 #include "nsMathUtils.h"
   9 #include "nsSize.h"
  10 #include "ImageContainer.h"
  11
  12 #include <stdint.h>
  13
  14 namespace mozilla {
  15
  16 using layers::PlanarYCbCrImage;
  17
  18 // Converts from number of audio frames to microseconds, given the specified
  19 // audio rate.
  20 CheckedInt64 FramesToUsecs(int64_t aFrames, uint32_t aRate) {
  21   return (CheckedInt64(aFrames) * USECS_PER_S) / aRate;
  22 }
  23
  24 // Converts from microseconds to number of audio frames, given the specified
  25 // audio rate.
  26 CheckedInt64 UsecsToFrames(int64_t aUsecs, uint32_t aRate) {
  27   return (CheckedInt64(aUsecs) * aRate) / USECS_PER_S;
  28 }
  29
  30 static int32_t ConditionDimension(float aValue)
  31 {
  32   // This will exclude NaNs and too-big values.
  33   if (aValue > 1.0 && aValue <= INT32_MAX)
  34     return int32_t(NS_round(aValue));
  35   return 0;
  36 }
  37
  38 void ScaleDisplayByAspectRatio(nsIntSize& aDisplay, float aAspectRatio)
  39 {
  40   if (aAspectRatio > 1.0) {
  41     // Increase the intrinsic width
  42     aDisplay.width = ConditionDimension(aAspectRatio * aDisplay.width);
  43   } else {
  44     // Increase the intrinsic height
  45     aDisplay.height = ConditionDimension(aDisplay.height / aAspectRatio);
  46   }
  47 }
  48
  49 static int64_t BytesToTime(int64_t offset, int64_t length, int64_t durationUs) {
  50   NS_ASSERTION(length > 0, "Must have positive length");
  51   double r = double(offset) / double(length);
  52   if (r > 1.0)
  53     r = 1.0;
  54   return int64_t(double(durationUs) * r);
  55 }
  56
  57 void GetEstimatedBufferedTimeRanges(mozilla::MediaResource* aStream,
  58                                     int64_t aDurationUsecs,
  59                                     mozilla::dom::TimeRanges* aOutBuffered)
  60 {
  61   // Nothing to cache if the media takes 0us to play.
  62   if (aDurationUsecs <= 0 || !aStream || !aOutBuffered)
  63     return;
  64
  65   // Special case completely cached files.  This also handles local files.
  66   if (aStream->IsDataCachedToEndOfResource(0)) {
  67     aOutBuffered->Add(0, double(aDurationUsecs) / USECS_PER_S);
  68     return;
  69   }
  70
  71   int64_t totalBytes = aStream->GetLength();
  72
  73   // If we can't determine the total size, pretend that we have nothing
  74   // buffered. This will put us in a state of eternally-low-on-undecoded-data
  75   // which is not great, but about the best we can do.
  76   if (totalBytes <= 0)
  77     return;
  78
  79   int64_t startOffset = aStream->GetNextCachedData(0);
  80   while (startOffset >= 0) {
  81     int64_t endOffset = aStream->GetCachedDataEnd(startOffset);
  82     // Bytes [startOffset..endOffset] are cached.
  83     NS_ASSERTION(startOffset >= 0, "Integer underflow in GetBuffered");
  84     NS_ASSERTION(endOffset >= 0, "Integer underflow in GetBuffered");
  85
  86     int64_t startUs = BytesToTime(startOffset, totalBytes, aDurationUsecs);
  87     int64_t endUs = BytesToTime(endOffset, totalBytes, aDurationUsecs);
  88     if (startUs != endUs) {
  89       aOutBuffered->Add(double(startUs) / USECS_PER_S,
  90                         double(endUs) / USECS_PER_S);
  91     }
  92     startOffset = aStream->GetNextCachedData(endOffset);
  93   }
  94   return;
  95 }
  96
  97 bool
  98 IsVideoContentType(const nsCString& aContentType)
  99 {
 100   NS_NAMED_LITERAL_CSTRING(video, "video");
 101   if (FindInReadable(video, aContentType)) {
 102     return true;
 103   }
 104   return false;
 105 }
 106
 107 bool
 108 IsValidVideoRegion(const nsIntSize& aFrame, const nsIntRect& aPicture,
 109                    const nsIntSize& aDisplay)
 110 {
 111   return
 112     aFrame.width <= PlanarYCbCrImage::MAX_DIMENSION &&
 113     aFrame.height <= PlanarYCbCrImage::MAX_DIMENSION &&
 114     aFrame.width * aFrame.height <= MAX_VIDEO_WIDTH * MAX_VIDEO_HEIGHT &&
 115     aFrame.width * aFrame.height != 0 &&
 116     aPicture.width <= PlanarYCbCrImage::MAX_DIMENSION &&
 117     aPicture.x < PlanarYCbCrImage::MAX_DIMENSION &&
 118     aPicture.x + aPicture.width < PlanarYCbCrImage::MAX_DIMENSION &&
 119     aPicture.height <= PlanarYCbCrImage::MAX_DIMENSION &&
 120     aPicture.y < PlanarYCbCrImage::MAX_DIMENSION &&
 121     aPicture.y + aPicture.height < PlanarYCbCrImage::MAX_DIMENSION &&
 122     aPicture.width * aPicture.height <= MAX_VIDEO_WIDTH * MAX_VIDEO_HEIGHT &&
 123     aPicture.width * aPicture.height != 0 &&
 124     aDisplay.width <= PlanarYCbCrImage::MAX_DIMENSION &&
 125     aDisplay.height <= PlanarYCbCrImage::MAX_DIMENSION &&
 126     aDisplay.width * aDisplay.height <= MAX_VIDEO_WIDTH * MAX_VIDEO_HEIGHT &&
 127     aDisplay.width * aDisplay.height != 0;
 128 }
 129
 130 } // end namespace mozilla