VideoStreamFactory.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at https://mozilla.org/MPL/2.0/. */

#ifndef VideoStreamFactory_h

#define VideoStreamFactory_h

#include "CodecConfig.h"

#include "mozilla/Atomics.h"

#include "mozilla/DataMutex.h"

#include "mozilla/gfx/Point.h"

#include "mozilla/UniquePtr.h"

#include "api/video/video_source_interface.h"

#include "common_video/framerate_controller.h"

#include "rtc_base/time_utils.h"

#include "video/config/video_encoder_config.h"

namespace webrtc {

class VideoFrame;

namespace mozilla {

// Factory class for VideoStreams... vie_encoder.cc will call this to

// reconfigure.

class VideoStreamFactory

    : public webrtc::VideoEncoderConfig::VideoStreamFactoryInterface {

 public:

  struct ResolutionAndBitrateLimits {

    int resolution_in_mb;

    int min_bitrate_bps;

    int start_bitrate_bps;

    int max_bitrate_bps;

};

  static ResolutionAndBitrateLimits GetLimitsFor(unsigned int aWidth,

                                                 unsigned int aHeight,

                                                 int aCapBps = 0);

  VideoStreamFactory(VideoCodecConfig aConfig,

                     webrtc::VideoCodecMode aCodecMode, int aMinBitrate,

                     int aStartBitrate, int aPrefMaxBitrate,

                     int aNegotiatedMaxBitrate,

                     const rtc::VideoSinkWants& aWants, bool aLockScaling)

      : mCodecMode(aCodecMode),

        mMaxFramerateForAllStreams(std::numeric_limits<unsigned int>::max()),

        mCodecConfig(std::forward<VideoCodecConfig>(aConfig)),

        mMinBitrate(aMinBitrate),

        mStartBitrate(aStartBitrate),

        mPrefMaxBitrate(aPrefMaxBitrate),

        mNegotiatedMaxBitrate(aNegotiatedMaxBitrate),

        mFramerateController("VideoStreamFactory::mFramerateController"),

        mWants(aWants),

        mLockScaling(aLockScaling) {}

  // This gets called off-main thread and may hold internal webrtc.org

  // locks. May *NOT* lock the conduit's mutex, to avoid deadlocks.

  std::vector<webrtc::VideoStream> CreateEncoderStreams(

      const webrtc::FieldTrialsView& field_trials, int aWidth, int aHeight,

      const webrtc::VideoEncoderConfig& aConfig) override;

/**

   * Called by CreateEncoderStreams and

   * WebrtcVideoConduit::OnControlConfigChange to set VideoStream.max_framerate.

*/

  void SelectMaxFramerate(int aWidth, int aHeight,

                          const VideoCodecConfig::Encoding& aEncoding,

                          webrtc::VideoStream& aVideoStream);

/**

   * Function to select and change the encoding resolution based on incoming

   * frame size and current available bandwidth.

   * @param width, height: dimensions of the frame

*/

  void SelectMaxFramerateForAllStreams(unsigned short aWidth,

                                       unsigned short aHeight);

/**

   * Function to determine if the frame should be dropped based on the given

   * frame's resolution (combined with the factory's scaleResolutionDownBy) or

   * timestamp.

   * @param aFrame frame to be evaluated.

   * @return true if frame should be dropped, false otehrwise.

*/

  bool ShouldDropFrame(const webrtc::VideoFrame& aFrame);

 private:

/**

   * Function to calculate a scaled down width and height based on

   * scaleDownByResolution, maxFS, and max pixel count settings.

   * @param aWidth current frame width

   * @param aHeight current frame height

   * @param aScaleDownByResolution value to scale width and height down by.

   * @param aMaxPixelCount maximum number of pixels wanted in a frame.

   * @return a gfx:IntSize containing  width and height to use. These may match

   * the aWidth and aHeight passed in if no scaling was needed.

*/

  gfx::IntSize CalculateScaledResolution(int aWidth, int aHeight,

                                         double aScaleDownByResolution,

                                         unsigned int aMaxPixelCount);

/**

   * Function to select and change the encoding frame rate based on incoming

   * frame rate, current frame size and max-mbps setting.

   * @param aOldFramerate current framerate

   * @param aSendingWidth width of frames being sent

   * @param aSendingHeight height of frames being sent

   * @return new framerate meeting max-mbps requriements based on frame size

*/

  unsigned int SelectFrameRate(unsigned int aOldFramerate,

                               unsigned short aSendingWidth,

                               unsigned short aSendingHeight);

  // Used to limit number of streams for screensharing.

  Atomic<webrtc::VideoCodecMode> mCodecMode;

  // The framerate we're currently sending at.

  Atomic<unsigned int> mMaxFramerateForAllStreams;

  // The current send codec config, containing simulcast layer configs.

  const VideoCodecConfig mCodecConfig;

  // Bitrate limits in bps.

  const int mMinBitrate = 0;

  const int mStartBitrate = 0;

  const int mPrefMaxBitrate = 0;

  const int mNegotiatedMaxBitrate = 0;

  // DatamMutex used as object is mutated from a libwebrtc thread and

  // a seperate thread used to pass video frames to libwebrtc.

  DataMutex<webrtc::FramerateController> mFramerateController;

  const rtc::VideoSinkWants mWants;

  const bool mLockScaling;

};

}  // namespace mozilla

#endif