gecko-dev/dom/media/VideoFrameConverter.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 http://mozilla.org/MPL/2.0/. */

#ifndef VideoFrameConverter_h
#define VideoFrameConverter_h

#include "ImageContainer.h"
#include "ImageConversion.h"
#include "Pacer.h"
#include "PerformanceRecorder.h"
#include "VideoSegment.h"
#include "VideoUtils.h"
#include "nsISupportsImpl.h"
#include "nsThreadUtils.h"
#include "jsapi/RTCStatsReport.h"
#include "mozilla/TaskQueue.h"
#include "mozilla/dom/ImageBitmapBinding.h"
#include "mozilla/dom/ImageUtils.h"
#include "api/video/video_frame.h"
#include "common_video/include/video_frame_buffer_pool.h"
#include "common_video/include/video_frame_buffer.h"

// The number of frame buffers VideoFrameConverter may create before returning
// errors.
// Sometimes these are released synchronously but they can be forwarded all the
// way to the encoder for asynchronous encoding. With a pool size of 5,
// we allow 1 buffer for the current conversion, and 4 buffers to be queued at
// the encoder.
#define CONVERTER_BUFFER_POOL_SIZE 5

extern mozilla::LazyLogModule gMediaPipelineLog;
#define LOG(level, msg, ...) \
  MOZ_LOG(gMediaPipelineLog, level, (msg, ##__VA_ARGS__))

namespace mozilla {

enum class FrameDroppingPolicy {
  Allowed,
  Disabled,
};

// An async video frame format converter.
//
// Input is typically a MediaTrackListener driven by MediaTrackGraph.
//
// Output is passed through to VideoFrameConvertedEvent() whenever a frame is
// converted.
template <FrameDroppingPolicy DropPolicy = FrameDroppingPolicy::Allowed>
class VideoFrameConverterImpl {
 public:
  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(VideoFrameConverterImpl)

 protected:
  explicit VideoFrameConverterImpl(
      const dom::RTCStatsTimestampMaker& aTimestampMaker)
      : mTimestampMaker(aTimestampMaker),
        mTaskQueue(TaskQueue::Create(
            GetMediaThreadPool(MediaThreadType::WEBRTC_WORKER),
            "VideoFrameConverter")),
        mPacer(MakeAndAddRef<Pacer<FrameToProcess>>(
            mTaskQueue, mIdleFrameDuplicationInterval)),
        mBufferPool(false, CONVERTER_BUFFER_POOL_SIZE) {
    MOZ_COUNT_CTOR(VideoFrameConverterImpl);
  }

  void RegisterListener() {
    mPacingListener = mPacer->PacedItemEvent().Connect(
        mTaskQueue,
        [self = RefPtr(this)](FrameToProcess&& aFrame, TimeStamp aTime) {
          self->QueueForProcessing(std::move(aFrame.mImage), aTime,
                                   aFrame.mSize, aFrame.mForceBlack);
        });
  }

 public:
  void QueueVideoChunk(const VideoChunk& aChunk, bool aForceBlack) {
    gfx::IntSize size = aChunk.mFrame.GetIntrinsicSize();
    if (size.width == 0 || size.height == 0) {
      return;
    }

    TimeStamp t = aChunk.mTimeStamp;
    MOZ_ASSERT(!t.IsNull());

    mPacer->Enqueue(
        FrameToProcess(aChunk.mFrame.GetImage(), t, size, aForceBlack), t);
  }

  /**
   * An active VideoFrameConverter actively converts queued video frames.
   * While inactive, we keep track of the frame most recently queued for
   * processing, so it can be immediately sent out once activated.
   */
  void SetActive(bool aActive) {
    MOZ_ALWAYS_SUCCEEDS(mTaskQueue->Dispatch(NS_NewRunnableFunction(
        __func__, [self = RefPtr<VideoFrameConverterImpl>(this), this, aActive,
                   time = TimeStamp::Now()] {
          if (mActive == aActive) {
            return;
          }
          LOG(LogLevel::Debug, "VideoFrameConverter %p is now %s", this,
              aActive ? "active" : "inactive");
          mActive = aActive;
          if (aActive && mLastFrameQueuedForProcessing.Serial() != -2) {
            // After activating, we re-process the last image that was queued
            // for processing so it can be immediately sent. The image is reset
            // so it doesn't get dropped if within the duplicate frame interval.
            QueueForProcessing(std::move(mLastFrameQueuedForProcessing.mImage),
                               std::max(mLastFrameQueuedForProcessing.mTime +
                                            TimeDuration::FromMicroseconds(1),
                                        time),
                               mLastFrameQueuedForProcessing.mSize,
                               mLastFrameQueuedForProcessing.mForceBlack);
          }
        })));
  }

  void SetTrackEnabled(bool aTrackEnabled) {
    MOZ_ALWAYS_SUCCEEDS(mTaskQueue->Dispatch(NS_NewRunnableFunction(
        __func__, [self = RefPtr<VideoFrameConverterImpl>(this), this,
                   aTrackEnabled, time = TimeStamp::Now()] {
          if (mTrackEnabled == aTrackEnabled) {
            return;
          }
          LOG(LogLevel::Debug, "VideoFrameConverterImpl %p Track is now %s",
              this, aTrackEnabled ? "enabled" : "disabled");
          mTrackEnabled = aTrackEnabled;
          if (!aTrackEnabled) {
            // After disabling we immediately send a frame as black, so it can
            // be seen quickly, even if no frames are flowing. If no frame has
            // been queued for processing yet, we use the FrameToProcess default
            // size (640x480).
            QueueForProcessing(/* aImage= */ nullptr,
                               std::max(mLastFrameQueuedForProcessing.mTime +
                                            TimeDuration::FromMicroseconds(1),
                                        time),
                               mLastFrameQueuedForProcessing.mSize,
                               /* aForceBlack= */ true);
          }
        })));
  }

  void SetTrackingId(TrackingId aTrackingId) {
    MOZ_ALWAYS_SUCCEEDS(mTaskQueue->Dispatch(NS_NewRunnableFunction(
        __func__, [self = RefPtr<VideoFrameConverterImpl>(this), this,
                   id = std::move(aTrackingId)]() mutable {
          mTrackingId = Some(std::move(id));
        })));
  }

  void SetIdleFrameDuplicationInterval(TimeDuration aInterval) {
    MOZ_ALWAYS_SUCCEEDS(mTaskQueue->Dispatch(NS_NewRunnableFunction(
        __func__, [self = RefPtr(this), this, aInterval] {
          mIdleFrameDuplicationInterval = aInterval;
        })));
    mPacer->SetDuplicationInterval(aInterval);
  }

  void Shutdown() {
    mPacer->Shutdown()->Then(
        mTaskQueue, __func__,
        [self = RefPtr<VideoFrameConverterImpl>(this), this] {
          mPacingListener.DisconnectIfExists();
          mBufferPool.Release();
          mLastFrameQueuedForProcessing = FrameToProcess();
          mLastFrameConverted = Nothing();
        });
  }

  MediaEventSourceExc<webrtc::VideoFrame>& VideoFrameConvertedEvent() {
    return mVideoFrameConvertedEvent;
  }

 protected:
  struct FrameToProcess {
    FrameToProcess() = default;

    FrameToProcess(RefPtr<layers::Image> aImage, TimeStamp aTime,
                   gfx::IntSize aSize, bool aForceBlack)
        : mImage(std::move(aImage)),
          mTime(aTime),
          mSize(aSize),
          mForceBlack(aForceBlack) {}

    RefPtr<layers::Image> mImage;
    TimeStamp mTime = TimeStamp::Now();
    gfx::IntSize mSize = gfx::IntSize(640, 480);
    bool mForceBlack = false;

    int32_t Serial() const {
      if (mForceBlack) {
        // Set the last-img check to indicate black.
        // -1 is not a guaranteed invalid serial. See bug 1262134.
        return -1;
      }
      if (!mImage) {
        // Set the last-img check to indicate reset.
        // -2 is not a guaranteed invalid serial. See bug 1262134.
        return -2;
      }
      return mImage->GetSerial();
    }
  };

  struct FrameConverted {
    FrameConverted(webrtc::VideoFrame aFrame, int32_t aSerial)
        : mFrame(std::move(aFrame)), mSerial(aSerial) {}

    webrtc::VideoFrame mFrame;
    int32_t mSerial;
  };

  MOZ_COUNTED_DTOR_VIRTUAL(VideoFrameConverterImpl)

  void VideoFrameConverted(webrtc::VideoFrame aVideoFrame, int32_t aSerial) {
    MOZ_ASSERT(mTaskQueue->IsCurrentThreadIn());

    LOG(LogLevel::Verbose,
        "VideoFrameConverterImpl %p: Converted a frame. Diff from last: %.3fms",
        this,
        static_cast<double>(aVideoFrame.timestamp_us() -
                            (mLastFrameConverted
                                 ? mLastFrameConverted->mFrame.timestamp_us()
                                 : aVideoFrame.timestamp_us())) /
            1000);

    // Check that time doesn't go backwards
    MOZ_ASSERT_IF(mLastFrameConverted,
                  aVideoFrame.timestamp_us() >
                      mLastFrameConverted->mFrame.timestamp_us());

    mLastFrameConverted = Some(FrameConverted(aVideoFrame, aSerial));

    mVideoFrameConvertedEvent.Notify(std::move(aVideoFrame));
  }

  void QueueForProcessing(RefPtr<layers::Image> aImage, TimeStamp aTime,
                          gfx::IntSize aSize, bool aForceBlack) {
    MOZ_ASSERT(mTaskQueue->IsCurrentThreadIn());

    FrameToProcess frame{std::move(aImage), aTime, aSize,
                         aForceBlack || !mTrackEnabled};

    if (frame.mTime <= mLastFrameQueuedForProcessing.mTime) {
      LOG(LogLevel::Debug,
          "VideoFrameConverterImpl %p: Dropping a frame because time did not "
          "progress (%.3fs)",
          this,
          (mLastFrameQueuedForProcessing.mTime - frame.mTime).ToSeconds());
      return;
    }

    if (frame.Serial() == mLastFrameQueuedForProcessing.Serial()) {
      // This is the same frame as the last one. We limit the same-frame rate,
      // and rewrite the time so the frame-gap is in multiples of the
      // duplication interval.
      //
      // The pacer only starts duplicating frames if there is no flow of frames
      // into it. There are other reasons the same frame could repeat here, and
      // at a shorter interval than the duplication interval. For instance after
      // the sender is disabled (SetTrackEnabled) but there is still a flow of
      // frames into the pacer. All disabled frames have the same serial.
      if (auto diff = frame.mTime - mLastFrameQueuedForProcessing.mTime;
          diff >= mIdleFrameDuplicationInterval) {
        auto diff_us = static_cast<int64_t>(diff.ToMicroseconds());
        auto idle_interval_us = static_cast<int64_t>(
            mIdleFrameDuplicationInterval.ToMicroseconds());
        auto multiples = diff_us / idle_interval_us;
        MOZ_ASSERT(multiples > 0);
        LOG(LogLevel::Verbose,
            "VideoFrameConverterImpl %p: Rewrote time interval for a duplicate "
            "frame from %.3fs to %.3fs",
            this,
            (frame.mTime - mLastFrameQueuedForProcessing.mTime).ToSeconds(),
            (mIdleFrameDuplicationInterval * multiples).ToSeconds());
        frame.mTime = mLastFrameQueuedForProcessing.mTime +
                      (mIdleFrameDuplicationInterval * multiples);
      } else {
        LOG(LogLevel::Verbose,
            "VideoFrameConverterImpl %p: Dropping a duplicate frame because "
            "the "
            "duplication interval (%.3fs) hasn't passed (%.3fs)",
            this, mIdleFrameDuplicationInterval.ToSeconds(),
            (frame.mTime - mLastFrameQueuedForProcessing.mTime).ToSeconds());
        return;
      }
    }

    mLastFrameQueuedForProcessing = std::move(frame);

    if (!mActive) {
      LOG(LogLevel::Debug,
          "VideoFrameConverterImpl %p: Ignoring a frame because we're inactive",
          this);
      return;
    }

    MOZ_ALWAYS_SUCCEEDS(mTaskQueue->Dispatch(NewRunnableMethod<FrameToProcess>(
        "VideoFrameConverterImpl::ProcessVideoFrame", this,
        &VideoFrameConverterImpl::ProcessVideoFrame,
        mLastFrameQueuedForProcessing)));
  }

  void ProcessVideoFrame(const FrameToProcess& aFrame) {
    MOZ_ASSERT(mTaskQueue->IsCurrentThreadIn());

    if constexpr (DropPolicy == FrameDroppingPolicy::Allowed) {
      if (aFrame.mTime < mLastFrameQueuedForProcessing.mTime) {
        LOG(LogLevel::Debug,
            "VideoFrameConverterImpl %p: Dropping a frame that is %.3f seconds "
            "before latest",
            this,
            (mLastFrameQueuedForProcessing.mTime - aFrame.mTime).ToSeconds());
        return;
      }
    }

    const webrtc::Timestamp time =
        dom::RTCStatsTimestamp::FromMozTime(mTimestampMaker, aFrame.mTime)
            .ToRealtime();

    if (mLastFrameConverted &&
        aFrame.Serial() == mLastFrameConverted->mSerial) {
      // This is the same input frame as last time. Avoid a conversion.
      webrtc::VideoFrame frame = mLastFrameConverted->mFrame;
      frame.set_timestamp_us(time.us());
      VideoFrameConverted(std::move(frame), mLastFrameConverted->mSerial);
      return;
    }

    if (aFrame.mForceBlack) {
      // Send a black image.
      rtc::scoped_refptr<webrtc::I420Buffer> buffer =
          mBufferPool.CreateI420Buffer(aFrame.mSize.width, aFrame.mSize.height);
      if (!buffer) {
        MOZ_DIAGNOSTIC_CRASH(
            "Buffers not leaving scope except for "
            "reconfig, should never leak");
        LOG(LogLevel::Warning,
            "VideoFrameConverterImpl %p: Creating a buffer for a black video "
            "frame failed",
            this);
        return;
      }

      LOG(LogLevel::Verbose,
          "VideoFrameConverterImpl %p: Sending a black video frame", this);
      webrtc::I420Buffer::SetBlack(buffer.get());

      VideoFrameConverted(webrtc::VideoFrame::Builder()
                              .set_video_frame_buffer(buffer)
                              .set_timestamp_us(time.us())
                              .build(),
                          aFrame.Serial());
      return;
    }

    if (!aFrame.mImage) {
      // Don't send anything for null images.
      return;
    }

    MOZ_ASSERT(aFrame.mImage->GetSize() == aFrame.mSize);

    RefPtr<layers::PlanarYCbCrImage> image =
        aFrame.mImage->AsPlanarYCbCrImage();
    if (image) {
      dom::ImageUtils utils(image);
      Maybe<dom::ImageBitmapFormat> format = utils.GetFormat();
      if (format.isSome() &&
          format.value() == dom::ImageBitmapFormat::YUV420P &&
          image->GetData()) {
        const layers::PlanarYCbCrData* data = image->GetData();
        rtc::scoped_refptr<webrtc::I420BufferInterface> video_frame_buffer =
            webrtc::WrapI420Buffer(
                aFrame.mImage->GetSize().width, aFrame.mImage->GetSize().height,
                data->mYChannel, data->mYStride, data->mCbChannel,
                data->mCbCrStride, data->mCrChannel, data->mCbCrStride,
                [image] { /* keep reference alive*/ });

        LOG(LogLevel::Verbose,
            "VideoFrameConverterImpl %p: Sending an I420 video frame", this);
        VideoFrameConverted(webrtc::VideoFrame::Builder()
                                .set_video_frame_buffer(video_frame_buffer)
                                .set_timestamp_us(time.us())
                                .build(),
                            aFrame.Serial());
        return;
      }
    }

    rtc::scoped_refptr<webrtc::I420Buffer> buffer =
        mBufferPool.CreateI420Buffer(aFrame.mSize.width, aFrame.mSize.height);
    if (!buffer) {
#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
      ++mFramesDropped;
#endif
      MOZ_DIAGNOSTIC_ASSERT(mFramesDropped <= 100, "Buffers must be leaking");
      LOG(LogLevel::Warning,
          "VideoFrameConverterImpl %p: Creating a buffer failed", this);
      return;
    }

#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
    mFramesDropped = 0;
#endif
    PerformanceRecorder<CopyVideoStage> rec(
        "VideoFrameConverterImpl::ConvertToI420"_ns, *mTrackingId,
        buffer->width(), buffer->height());
    nsresult rv =
        ConvertToI420(aFrame.mImage, buffer->MutableDataY(), buffer->StrideY(),
                      buffer->MutableDataU(), buffer->StrideU(),
                      buffer->MutableDataV(), buffer->StrideV());

    if (NS_FAILED(rv)) {
      LOG(LogLevel::Warning,
          "VideoFrameConverterImpl %p: Image conversion failed", this);
      return;
    }
    rec.Record();

    VideoFrameConverted(webrtc::VideoFrame::Builder()
                            .set_video_frame_buffer(buffer)
                            .set_timestamp_us(time.us())
                            .build(),
                        aFrame.Serial());
  }

 public:
  const dom::RTCStatsTimestampMaker mTimestampMaker;

  const RefPtr<TaskQueue> mTaskQueue;

 protected:
  TimeDuration mIdleFrameDuplicationInterval = TimeDuration::Forever();

  // Used to pace future frames close to their rendering-time. Thread-safe.
  const RefPtr<Pacer<FrameToProcess>> mPacer;

  MediaEventProducerExc<webrtc::VideoFrame> mVideoFrameConvertedEvent;

  // Accessed only from mTaskQueue.
  MediaEventListener mPacingListener;
  webrtc::VideoFrameBufferPool mBufferPool;
  FrameToProcess mLastFrameQueuedForProcessing;
  Maybe<FrameConverted> mLastFrameConverted;
  bool mActive = false;
  bool mTrackEnabled = true;
  Maybe<TrackingId> mTrackingId;
#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED
  size_t mFramesDropped = 0;
#endif
};

class VideoFrameConverter final
    : public VideoFrameConverterImpl<FrameDroppingPolicy::Allowed> {
 protected:
  explicit VideoFrameConverter(
      const dom::RTCStatsTimestampMaker& aTimestampMaker)
      : VideoFrameConverterImpl(aTimestampMaker) {}

 public:
  static already_AddRefed<VideoFrameConverter> Create(
      const dom::RTCStatsTimestampMaker& aTimestampMaker) {
    RefPtr<VideoFrameConverter> converter =
        new VideoFrameConverter(aTimestampMaker);
    converter->RegisterListener();
    return converter.forget();
  }
};

}  // namespace mozilla

#undef LOG

#endif  // VideoFrameConverter_h