tor-browser

video_source_interface.h (5763B)

---

/*
*  Copyright (c) 2016 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.
*/

#ifndef API_VIDEO_VIDEO_SOURCE_INTERFACE_H_
#define API_VIDEO_VIDEO_SOURCE_INTERFACE_H_

#include <limits>
#include <optional>
#include <vector>

#include "api/video/video_sink_interface.h"
#include "rtc_base/system/rtc_export.h"

namespace webrtc {

// VideoSinkWants is used for notifying the source of properties a video frame
// should have when it is delivered to a certain sink.
struct RTC_EXPORT VideoSinkWants {
 struct FrameSize {
   FrameSize(int width, int height) : width(width), height(height) {}
   FrameSize(const FrameSize&) = default;
   ~FrameSize() = default;

   int width;
   int height;
 };

 VideoSinkWants();
 VideoSinkWants(const VideoSinkWants&);
 ~VideoSinkWants();

 // Tells the source whether the sink wants frames with rotation applied.
 // By default, any rotation must be applied by the sink.
 bool rotation_applied = false;

 // Tells the source that the sink only wants black frames.
 bool black_frames = false;

 // Tells the source the maximum number of pixels the sink wants.
 int max_pixel_count = std::numeric_limits<int>::max();
 // Tells the source the desired number of pixels the sinks wants. This will
 // typically be used when stepping the resolution up again when conditions
 // have improved after an earlier downgrade. The source should select the
 // closest resolution to this pixel count, but if max_pixel_count is set, it
 // still sets the absolute upper bound.
 std::optional<int> target_pixel_count;
 // Tells the source the maximum framerate the sink wants.
 int max_framerate_fps = std::numeric_limits<int>::max();

 // Tells the source that the sink wants width and height of the video frames
 // to be divisible by `resolution_alignment`.
 // For example: With I420, this value would be a multiple of 2.
 // Note that this field is unrelated to any horizontal or vertical stride
 // requirements the encoder has on the incoming video frame buffers.
 int resolution_alignment = 1;

 // The resolutions that sink is configured to consume. If the sink is an
 // encoder this is what the encoder is configured to encode. In singlecast we
 // only encode one resolution, but in simulcast and SVC this can mean multiple
 // resolutions per frame.
 //
 // The sink is always configured to consume a subset of the
 // VideoFrame's resolution. In the case of encoding, we usually encode
 // at VideoFrame's resolution but this may not always be the case due
 // to scaleResolutionDownBy or turning off simulcast or SVC layers.
 //
 // For example, we may capture at 720p and due to adaptation (e.g. applying
 // `max_pixel_count` constraints) create VideoFrames of size 480p, but
 // if we do scaleResolutionDownBy:2 then the only resolution we end up
 // encoding is 240p. In this case we still need to provide VideoFrames
 // of size 480p but we can optimize internal buffers for 240p, avoiding
 // downsampling to 480p if possible.
 //
 // Note that the `resolutions` can change while frames are in flight and
 // should only be used as a hint when constructing the VideoFrame.
 std::vector<FrameSize> resolutions;

 // This is the resolution requested by the user using RtpEncodingParameters,
 // which is the maximum `scale_resolution_down_by` value of any encoding.
 std::optional<FrameSize> requested_resolution;

 // `is_active` : Is this VideoSinkWants from an encoder that is encoding any
 // layer. IF YES, it will affect how the VideoAdapter will choose to
 // prioritize the OnOutputFormatRequest vs. requested_resolution. IF NO,
 // VideoAdapter consider this VideoSinkWants as a passive listener (e.g a
 // VideoRenderer or a VideoEncoder that is not currently actively encoding).
 bool is_active = false;

 // This sub-struct contains information computed by VideoBroadcaster
 // that aggregates several VideoSinkWants (and sends them to
 // AdaptedVideoTrackSource).
 struct Aggregates {
   // `any_active_without_requested_resolution` is set by VideoBroadcaster
   // when aggregating sink wants if there exists any sink (encoder) that is
   // active but has not set the `requested_resolution`, i.e is relying on
   // OnOutputFormatRequest to handle encode resolution.
   bool any_active_without_requested_resolution = false;
 };
 std::optional<Aggregates> aggregates;
};

inline bool operator==(const VideoSinkWants::FrameSize& a,
                      const VideoSinkWants::FrameSize& b) {
 return a.width == b.width && a.height == b.height;
}

inline bool operator!=(const VideoSinkWants::FrameSize& a,
                      const VideoSinkWants::FrameSize& b) {
 return !(a == b);
}

template <typename VideoFrameT>
class VideoSourceInterface {
public:
 virtual ~VideoSourceInterface() = default;

 virtual void AddOrUpdateSink(VideoSinkInterface<VideoFrameT>* sink,
                              const VideoSinkWants& wants) = 0;
 // RemoveSink must guarantee that at the time the method returns,
 // there is no current and no future calls to VideoSinkInterface::OnFrame.
 virtual void RemoveSink(VideoSinkInterface<VideoFrameT>* sink) = 0;

 // Request underlying source to capture a new frame.
 // TODO(crbug/1255737): make pure virtual once downstream projects adapt.
 virtual void RequestRefreshFrame() {}
};

}  //  namespace webrtc

#endif  // API_VIDEO_VIDEO_SOURCE_INTERFACE_H_