video_adapter.h - mozsearch

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/*

 *  Copyright (c) 2010 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 MEDIA_BASE_VIDEO_ADAPTER_H_

#define MEDIA_BASE_VIDEO_ADAPTER_H_

#include <stdint.h>

#include <string>

#include <utility>

#include "absl/types/optional.h"

#include "api/video/video_source_interface.h"

#include "common_video/framerate_controller.h"

#include "media/base/video_common.h"

#include "rtc_base/synchronization/mutex.h"

#include "rtc_base/system/rtc_export.h"

#include "rtc_base/thread_annotations.h"

namespace cricket {

// VideoAdapter adapts an input video frame to an output frame based on the

// specified input and output formats. The adaptation includes dropping frames

// to reduce frame rate and scaling frames.

// VideoAdapter is thread safe.

class RTC_EXPORT VideoAdapter {

 public:

  VideoAdapter();

  // The source requests output frames whose width and height are divisible

  // by `source_resolution_alignment`.

  explicit VideoAdapter(int source_resolution_alignment);

  virtual ~VideoAdapter();

  VideoAdapter(const VideoAdapter&) = delete;

  VideoAdapter& operator=(const VideoAdapter&) = delete;

  // Return the adapted resolution and cropping parameters given the

  // input resolution. The input frame should first be cropped, then

  // scaled to the final output resolution. Returns true if the frame

  // should be adapted, and false if it should be dropped.

  bool AdaptFrameResolution(int in_width,

                            int in_height,

                            int64_t in_timestamp_ns,

                            int* cropped_width,

                            int* cropped_height,

                            int* out_width,

                            int* out_height) RTC_LOCKS_EXCLUDED(mutex_);

  // DEPRECATED. Please use OnOutputFormatRequest below.

  // TODO(asapersson): Remove this once it is no longer used.

  // Requests the output frame size and frame interval from

  // `AdaptFrameResolution` to not be larger than `format`. Also, the input

  // frame size will be cropped to match the requested aspect ratio. The

  // requested aspect ratio is orientation agnostic and will be adjusted to

  // maintain the input orientation, so it doesn't matter if e.g. 1280x720 or

  // 720x1280 is requested.

  // Note: Should be called from the source only.

  void OnOutputFormatRequest(const absl::optional<VideoFormat>& format)

      RTC_LOCKS_EXCLUDED(mutex_);

  // Requests output frame size and frame interval from `AdaptFrameResolution`.

  // `target_aspect_ratio`: The input frame size will be cropped to match the

  // requested aspect ratio. The aspect ratio is orientation agnostic and will

  // be adjusted to maintain the input orientation (i.e. it doesn't matter if

  // e.g. <1280,720> or <720,1280> is requested).

  // `max_pixel_count`: The maximum output frame size.

  // `max_fps`: The maximum output framerate.

  // Note: Should be called from the source only.

  void OnOutputFormatRequest(

      const absl::optional<std::pair<int, int>>& target_aspect_ratio,

      const absl::optional<int>& max_pixel_count,

      const absl::optional<int>& max_fps) RTC_LOCKS_EXCLUDED(mutex_);

  // Same as above, but allows setting two different target aspect ratios

  // depending on incoming frame orientation. This gives more fine-grained

  // control and can e.g. be used to force landscape video to be cropped to

  // portrait video.

  void OnOutputFormatRequest(

      const absl::optional<std::pair<int, int>>& target_landscape_aspect_ratio,

      const absl::optional<int>& max_landscape_pixel_count,

      const absl::optional<std::pair<int, int>>& target_portrait_aspect_ratio,

      const absl::optional<int>& max_portrait_pixel_count,

      const absl::optional<int>& max_fps) RTC_LOCKS_EXCLUDED(mutex_);

  // Requests the output frame size from `AdaptFrameResolution` to have as close

  // as possible to `sink_wants.target_pixel_count` pixels (if set)

  // but no more than `sink_wants.max_pixel_count`.

  // `sink_wants.max_framerate_fps` is essentially analogous to

  // `sink_wants.max_pixel_count`, but for framerate rather than resolution.

  // Set `sink_wants.max_pixel_count` and/or `sink_wants.max_framerate_fps` to

  // std::numeric_limit<int>::max() if no upper limit is desired.

  // The sink resolution alignment requirement is given by

  // `sink_wants.resolution_alignment`.

  // Note: Should be called from the sink only.

  void OnSinkWants(const rtc::VideoSinkWants& sink_wants)

      RTC_LOCKS_EXCLUDED(mutex_);

  // Returns maximum image area, which shouldn't impose any adaptations.

  // Can return `numeric_limits<int>::max()` if no limit is set.

  int GetTargetPixels() const;

  // Returns current frame-rate limit.

  // Can return `numeric_limits<float>::infinity()` if no limit is set.

  float GetMaxFramerate() const;

 private:

  // Determine if frame should be dropped based on input fps and requested fps.

  bool DropFrame(int64_t in_timestamp_ns) RTC_EXCLUSIVE_LOCKS_REQUIRED(mutex_);

  int frames_in_ RTC_GUARDED_BY(mutex_);      // Number of input frames.

  int frames_out_ RTC_GUARDED_BY(mutex_);     // Number of output frames.

  int frames_scaled_ RTC_GUARDED_BY(mutex_);  // Number of frames scaled.

  int adaption_changes_

      RTC_GUARDED_BY(mutex_);  // Number of changes in scale factor.

  int previous_width_ RTC_GUARDED_BY(mutex_);  // Previous adapter output width.

  int previous_height_

      RTC_GUARDED_BY(mutex_);  // Previous adapter output height.

  // The fixed source resolution alignment requirement.

  const int source_resolution_alignment_;

  // The currently applied resolution alignment, as given by the requirements:

  //  - the fixed `source_resolution_alignment_`; and

  //  - the latest `sink_wants.resolution_alignment`.

  int resolution_alignment_ RTC_GUARDED_BY(mutex_);

  // Max number of pixels/fps requested via calls to OnOutputFormatRequest,

  // OnResolutionFramerateRequest respectively.

  // The adapted output format is the minimum of these.

  struct OutputFormatRequest {

    absl::optional<std::pair<int, int>> target_landscape_aspect_ratio;

    absl::optional<int> max_landscape_pixel_count;

    absl::optional<std::pair<int, int>> target_portrait_aspect_ratio;

    absl::optional<int> max_portrait_pixel_count;

    absl::optional<int> max_fps;

    // For logging.

    std::string ToString() const;

};

  OutputFormatRequest output_format_request_ RTC_GUARDED_BY(mutex_);

  int resolution_request_target_pixel_count_ RTC_GUARDED_BY(mutex_);

  int resolution_request_max_pixel_count_ RTC_GUARDED_BY(mutex_);

  int max_framerate_request_ RTC_GUARDED_BY(mutex_);

  // Stashed OutputFormatRequest that is used to save value of

  // OnOutputFormatRequest in case all active encoders are using

  // requested_resolution. I.e when all active encoders are using

  // requested_resolution, the call to OnOutputFormatRequest is ignored

  // and the value from requested_resolution is used instead (to scale/crop

  // frame). This allows for an application to only use

  // RtpEncodingParameters::request_resolution and get the same behavior as if

  // it had used VideoAdapter::OnOutputFormatRequest.

  absl::optional<OutputFormatRequest> stashed_output_format_request_

      RTC_GUARDED_BY(mutex_);

  webrtc::FramerateController framerate_controller_ RTC_GUARDED_BY(mutex_);

  // The critical section to protect the above variables.

  mutable webrtc::Mutex mutex_;

};

}  // namespace cricket

#endif  // MEDIA_BASE_VIDEO_ADAPTER_H_