blob: 484ffc6ebec67895c0e0e8c383d0bb038ff20c4f [file] [log] [blame]
// Copyright 2017 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 <string>
#include <vector>
#include "base/optional.h"
#include "content/common/content_export.h"
#include "content/renderer/media/stream/media_stream_constraints_util.h"
#include "media/capture/video_capture_types.h"
#include "third_party/blink/public/mojom/mediastream/media_devices.mojom.h"
namespace blink {
class WebString;
class WebMediaConstraints;
} // namespace blink
namespace content {
// Calculates and returns videoKind value for |format|.
// See
CONTENT_EXPORT blink::WebString GetVideoKindForFormat(
const media::VideoCaptureFormat& format);
CONTENT_EXPORT blink::WebMediaStreamTrack::FacingMode ToWebFacingMode(
media::VideoFacingMode video_facing);
CONTENT_EXPORT blink::WebMediaStreamTrack::DisplayCaptureSurfaceType
ToWebDisplaySurface(media::mojom::DisplayCaptureSurfaceType display_surface);
CONTENT_EXPORT blink::WebMediaStreamTrack::CursorCaptureType
ToWebCursorCaptureType(media::mojom::CursorCaptureType cursor);
struct CONTENT_EXPORT VideoDeviceCaptureCapabilities {
VideoDeviceCaptureCapabilities(VideoDeviceCaptureCapabilities&& other);
VideoDeviceCaptureCapabilities& operator=(
VideoDeviceCaptureCapabilities&& other);
// Each field is independent of each other.
std::vector<base::Optional<bool>> noise_reduction_capabilities;
// This function performs source, source-settings and track-settings selection
// based on the given |capabilities| and |constraints|.
// Chromium performs constraint resolution in two steps. First, a source and its
// settings are selected, then track settings are selected based on the source
// settings. This function implements both steps. Sources are not a user-visible
// concept, so the spec only specifies an algorithm for track settings.
// The algorithm for sources is compatible with the spec algorithm for tracks,
// as defined in,
// but it is customized to account for differences between sources and tracks,
// and to break ties when multiple source settings are equally good according to
// the spec algorithm.
// In this algorithm, a candidate source is defined as a specific video input
// device opened with a specific resolution and frame rate, together with a
// specific noise-reduction setting.
// The main difference between a source and a track with regards to the spec
// algorithm is that a candidate source can support a range of values for some
// properties while a candidate track supports a single value. For example,
// cropping and rescaling allows a source with native resolution AxB to support
// the range of resolutions from 1x1 to AxB.
// Only candidates that satisfy the basic constraint set are valid. If no
// candidate can satisfy the basic constraint set, this function returns
// a result without value and with the name of a failed constraint accessible
// via the failed_constraint_name() method. If at least one candidate that
// satisfies the basic constraint set can be found, this function returns a
// result with a valid value.
// If there are no candidates at all, this function returns a result without
// value and an empty failed constraint name.
// The criteria to decide if a valid candidate source (i.e., one that satisfies
// the basic constraint set) is better than another one are as follows: 1. Given
// advanced constraint sets A[0],A[1]...,A[n], candidate C1 is better
// than candidate C2 if C1 supports the first advanced set for which C1's
// support is different than C2's support.
// Examples:
// * One advanced set, C1 supports it, and C2 does not. C1 is better.
// * Two sets, C1 supports both, C2 supports only the first. C1 is better.
// * Three sets, C1 supports the first and second set, C2 supports the first
// and third set. C1 is better.
// 2. C1 is better than C2 if C1 has a smaller fitness distance than C2. The
// fitness distance depends on the ability of the candidate to support ideal
// values in the basic constraint set. This is the final criterion defined in
// the spec. According to spec, all candidates that share the same fitness
// distance are equally acceptable, but this implementation has additional
// criteria to break ties.
// 3. C1 is better than C2 if C1 has a lower Chromium-specific custom distance
// from the basic constraint set that penalizes the amount of resolution and
// frame-rate adjustment required to satisfy the range and ideal value
// specified by width, height and frameRate constraints.
// For example, if constraints specify a resolution of exactly 1000x1000 for
// a track, then a candidate with a native resolution of 1200x1200
// is better than a candidate with a native resolution of 2000x2000. Both
// settings satisfy the constraint set because rescaling can be used to
// produce the track setting of 1000x1000, but 1200x1200 is considered better
// because it has lower resource usage.
// 4. C1 is better than C2 if its settings are closer to certain default
// settings that include the device ID, noise reduction, resolution,
// and frame rate, in that order. Note that there is no default facing mode
// or aspect ratio.
// This function uses the SelectVideoTrackAdapterSettings function to compute
// some track-specific settings. These are available in the returned value via
// the track_adapter_settings() accessor. For more details about the algorithm
// for track adapter settings, see the SelectVideoTrackAdapterSettings
// documentation.
VideoCaptureSettings CONTENT_EXPORT SelectSettingsVideoDeviceCapture(
const VideoDeviceCaptureCapabilities& capabilities,
const blink::WebMediaConstraints& constraints,
int default_width,
int default_height,
double default_frame_rate);
} // namespace content