content/media/VideoUtils.cpp
author Kan-Ru Chen <kanru@kanru.info>
Wed, 07 Mar 2012 12:03:25 +0100
changeset 91318 72bc6f12d1cc5237b7347f2ed737e929def0ad07
parent 90920 a771e4924188f8d6b3c6f99beb927fae0142f62b
child 98529 f4157e8c410708d76703f19e4dfb61859bfe32d8
child 112209 f977d96263c2bbf35d4308c576feb7cce22c665e
permissions -rw-r--r--
Bug 697132 - Implement wakelock interfaces. r=jlebar

/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla code.
 *
 * The Initial Developer of the Original Code is
 * the Mozilla Foundation.
 * Portions created by the Initial Developer are Copyright (C) 2010
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *  Chris Pearce <chris@pearce.org.nz>
 *
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 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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#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);
  }
}