video_common.h | Explore in Territory

/*
 *  Copyright (c) 2004 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

// Common definition for video, including fourcc and VideoFormat.

#ifndef MEDIA_BASE_VIDEO_COMMON_H_
#define MEDIA_BASE_VIDEO_COMMON_H_

#include <stdint.h>

#include <string>

#include "rtc_base/system/rtc_export.h"
#include "rtc_base/time_utils.h"

namespace cricket {

//////////////////////////////////////////////////////////////////////////////
// Definition of FourCC codes
//////////////////////////////////////////////////////////////////////////////
// Convert four characters to a FourCC code.
// Needs to be a macro otherwise the OS X compiler complains when the kFormat*
// constants are used in a switch.
#define CRICKET_FOURCC …
// Some pages discussing FourCC codes:
//   http://www.fourcc.org/yuv.php
//   http://v4l2spec.bytesex.org/spec/book1.htm
//   http://developer.apple.com/quicktime/icefloe/dispatch020.html
//   http://msdn.microsoft.com/library/windows/desktop/dd206750.aspx#nv12
//   http://people.xiph.org/~xiphmont/containers/nut/nut4cc.txt

// FourCC codes grouped according to implementation efficiency.
// Primary formats should convert in 1 efficient step.
// Secondary formats are converted in 2 steps.
// Auxilliary formats call primary converters.
enum FourCC { … };

#undef CRICKET_FOURCC

// Match any fourcc.

// We move this out of the enum because using it in many places caused
// the compiler to get grumpy, presumably since the above enum is
// backed by an int.
static const uint32_t FOURCC_ANY = …;

// Converts fourcc aliases into canonical ones.
uint32_t CanonicalFourCC(uint32_t fourcc);

// Get FourCC code as a string.
inline std::string GetFourccName(uint32_t fourcc) { … }

//////////////////////////////////////////////////////////////////////////////
// Definition of VideoFormat.
//////////////////////////////////////////////////////////////////////////////

// VideoFormat with Plain Old Data for global variables.
struct VideoFormatPod { … };

struct RTC_EXPORT VideoFormat : VideoFormatPod { … };

// Returns the largest positive integer that divides both `a` and `b`.
int GreatestCommonDivisor(int a, int b);

// Returns the smallest positive integer that is divisible by both `a` and `b`.
int LeastCommonMultiple(int a, int b);

}  // namespace cricket

#endif  // MEDIA_BASE_VIDEO_COMMON_H_
chromium/third_party/webrtc/media/base/video_common.h
