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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stddef.h>
#include <vector>
#include "build/build_config.h"
#include "media/base/video_types.h"
#include "media/capture/capture_export.h"
#include "ui/gfx/geometry/size.h"
namespace media {
// TODO(wjia): this type should be defined in a common place and
// shared with device manager.
typedef int VideoCaptureSessionId;
// Storage type for the pixels.
// TODO(mcasas): Consider making this an enum class.
// TODO(chfremer): Extend or remove this enum.
enum VideoPixelStorage {
// Policies for capture devices that have source content that varies in size.
// It is up to the implementation how the captured content will be transformed
// (e.g., scaling and/or letterboxing) in order to produce video frames that
// strictly adheree to one of these policies.
enum ResolutionChangePolicy {
// Capture device outputs a fixed resolution all the time. The resolution of
// the first frame is the resolution for all frames.
// Capture device is allowed to output frames of varying resolutions. The
// width and height will not exceed the maximum dimensions specified. The
// aspect ratio of the frames will match the aspect ratio of the maximum
// dimensions as closely as possible.
// Capture device is allowed to output frames of varying resolutions not
// exceeding the maximum dimensions specified.
// Must always be equal to largest entry in the enum.
// Potential values of the googPowerLineFrequency optional constraint passed to
// getUserMedia. Note that the numeric values are currently significant, and are
// used to map enum values to corresponding frequency values.
// TODO(ajose): Consider making this a class.
enum class PowerLineFrequency {
// Assert that the int:frequency mapping is correct.
static_assert(static_cast<int>(PowerLineFrequency::FREQUENCY_DEFAULT) == 0,
"static_cast<int>(FREQUENCY_DEFAULT) must equal 0.");
static_assert(static_cast<int>(PowerLineFrequency::FREQUENCY_50HZ) == 50,
"static_cast<int>(FREQUENCY_DEFAULT) must equal 50.");
static_assert(static_cast<int>(PowerLineFrequency::FREQUENCY_60HZ) == 60,
"static_cast<int>(FREQUENCY_DEFAULT) must equal 60.");
// Some drivers use rational time per frame instead of float frame rate, this
// constant k is used to convert between both: A fps -> [k/k*A] seconds/frame.
const int kFrameRatePrecision = 10000;
// Video capture format specification.
// This class is used by the video capture device to specify the format of every
// frame captured and returned to a client. It is also used to specify a
// supported capture format by a device.
struct CAPTURE_EXPORT VideoCaptureFormat {
VideoCaptureFormat(const gfx::Size& frame_size,
float frame_rate,
VideoPixelFormat pixel_format);
VideoCaptureFormat(const gfx::Size& frame_size,
float frame_rate,
VideoPixelFormat pixel_format,
VideoPixelStorage pixel_storage);
static std::string ToString(const VideoCaptureFormat& format);
static std::string PixelStorageToString(VideoPixelStorage storage);
// Compares the priority of the pixel formats. Returns true if |lhs| is the
// preferred pixel format in comparison with |rhs|. Returns false otherwise.
static bool ComparePixelFormatPreference(const VideoPixelFormat& lhs,
const VideoPixelFormat& rhs);
// Returns the required buffer size to hold an image of a given
// VideoCaptureFormat with no padding and tightly packed.
size_t ImageAllocationSize() const;
// Checks that all values are in the expected range. All limits are specified
// in media::Limits.
bool IsValid() const;
bool operator==(const VideoCaptureFormat& other) const {
return frame_size == other.frame_size && frame_rate == other.frame_rate &&
pixel_format == other.pixel_format;
gfx::Size frame_size;
float frame_rate;
VideoPixelFormat pixel_format;
VideoPixelStorage pixel_storage;
typedef std::vector<VideoCaptureFormat> VideoCaptureFormats;
// Parameters for starting video capture.
// This class is used by the client of a video capture device to specify the
// format of frames in which the client would like to have captured frames
// returned.
struct MEDIA_EXPORT VideoCaptureParams {
// Returns true if requested_format.IsValid() and all other values are within
// their expected ranges.
bool IsValid() const;
bool operator==(const VideoCaptureParams& other) const {
return requested_format == other.requested_format &&
resolution_change_policy == other.resolution_change_policy &&
power_line_frequency == other.power_line_frequency;
// Requests a resolution and format at which the capture will occur.
VideoCaptureFormat requested_format;
// Policy for resolution change.
ResolutionChangePolicy resolution_change_policy;
// User-specified power line frequency.
PowerLineFrequency power_line_frequency;
} // namespace media