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/* -*- Mode: C++; tab-width: 2; 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 VP8TrackEncoder_h_
#define VP8TrackEncoder_h_
#include "TrackEncoder.h"
#include "mozilla/RollingMean.h"
#include "TimeUnits.h"
#include "vpx/vpx_codec.h"
namespace mozilla {
typedef struct vpx_codec_ctx vpx_codec_ctx_t;
typedef struct vpx_codec_enc_cfg vpx_codec_enc_cfg_t;
typedef struct vpx_image vpx_image_t;
class VP8Metadata;
/**
* VP8TrackEncoder implements VideoTrackEncoder by using the libvpx library.
* We implement a realtime and variable frame rate encoder. In order to achieve
* that, there is a frame-drop encoding policy implemented in Encode().
*/
class VP8TrackEncoder : public VideoTrackEncoder {
enum EncodeOperation {
ENCODE_NORMAL_FRAME, // VP8 track encoder works normally.
ENCODE_I_FRAME, // The next frame will be encoded as I-Frame.
SKIP_FRAME, // Skip the next frame.
};
public:
VP8TrackEncoder(RefPtr<DriftCompensator> aDriftCompensator,
TrackRate aTrackRate,
MediaQueue<EncodedFrame>& aEncodedDataQueue,
FrameDroppingMode aFrameDroppingMode,
Maybe<float> aKeyFrameIntervalFactor = Nothing());
virtual ~VP8TrackEncoder();
already_AddRefed<TrackMetadataBase> GetMetadata() final;
protected:
nsresult Init(int32_t aWidth, int32_t aHeight, int32_t aDisplayWidth,
int32_t aDisplayHeight, float aEstimatedFrameRate) final;
private:
// Initiates the underlying vpx encoder.
nsresult InitInternal(int32_t aWidth, int32_t aHeight,
int32_t aMaxKeyFrameDistance);
// Get the EncodeOperation for next target frame.
EncodeOperation GetNextEncodeOperation(TimeDuration aTimeElapsed,
TimeDuration aProcessedDuration);
// Extracts the encoded data from the underlying encoder and returns it.
// Return value: An EncodedFrame if a frame was extracted.
// nullptr if we reached end-of-stream or nothing was available
// from the underlying encoder.
// An error nsresult otherwise.
Result<RefPtr<EncodedFrame>, nsresult> ExtractEncodedData();
// Takes the data in aSegment, encodes it, extracts it, and pushes it to
// mEncodedDataQueue.
nsresult Encode(VideoSegment* aSegment) final;
// Prepare the input data to the mVPXImageWrapper for encoding.
nsresult PrepareRawFrame(VideoChunk& aChunk);
// Re-configures an existing encoder with a new frame size.
nsresult Reconfigure(int32_t aWidth, int32_t aHeight,
int32_t aMaxKeyFrameDistance);
// Destroys the context and image wrapper. Does not de-allocate the structs.
void Destroy();
// Helper that calculates the desired max keyframe distance (vp8 config's
// max_kf_dist) based on configured key frame interval and recent framerate.
// Returns Nothing if not enough input data is available.
Maybe<int32_t> CalculateMaxKeyFrameDistance(
Maybe<float> aEstimatedFrameRate = Nothing()) const;
void SetMaxKeyFrameDistance(int32_t aMaxKeyFrameDistance);
// VP8 Metadata, set on successfuly Init and never modified again.
RefPtr<VP8Metadata> mMetadata;
// The width the encoder is currently configured with. The input frames to the
// underlying encoder must match this width, i.e., the underlying encoder will
// not do any resampling.
int mFrameWidth = 0;
// The height the encoder is currently configured with. The input frames to
// the underlying encoder must match this height, i.e., the underlying encoder
// will not do any resampling.
int mFrameHeight = 0;
// Encoded timestamp.
TrackTime mEncodedTimestamp = 0;
// Total duration in mTrackRate extracted from the underlying encoder.
CheckedInt64 mExtractedDuration;
// Total duration extracted from the underlying encoder.
media::TimeUnit mExtractedDurationUs;
// Muted frame, we only create it once.
RefPtr<layers::Image> mMuteFrame;
// I420 frame, for converting to I420.
UniquePtr<uint8_t[]> mI420Frame;
size_t mI420FrameSize = 0;
/**
* A duration of non-key frames in mTrackRate.
*/
TrackTime mDurationSinceLastKeyframe = 0;
/**
* The max interval at which a keyframe gets forced (causing video quality
* degradation). The encoder is configured to encode keyframes more often than
* this, though it can vary based on frame rate.
*/
const TimeDuration mKeyFrameInterval;
/**
* A factor used to multiply the estimated key-frame-interval based on
* mKeyFrameInterval (ms) with when configuring kf_max_dist in the encoder.
* The goal is to set it a bit below 1.0 to avoid falling back to forcing
* keyframes.
* NB that for purposes of testing the mKeyFrameInterval fallback this may be
* set to values higher than 1.0.
*/
float mKeyFrameIntervalFactor;
/**
* Time when we last updated the key-frame-distance.
*/
media::TimeUnit mLastKeyFrameDistanceUpdate;
/**
* The frame duration value last used to configure kf_max_dist.
*/
Maybe<int32_t> mMaxKeyFrameDistance;
/**
* The mean duration of recent frames.
*/
RollingMean<TimeDuration, TimeDuration> mMeanFrameDuration{30};
/**
* The mean wall-clock time it took to encode recent frames.
*/
RollingMean<TimeDuration, TimeDuration> mMeanFrameEncodeDuration{30};
// VP8 relative members.
// Codec context structure.
vpx_codec_ctx_t mVPXContext;
// Image Descriptor.
vpx_image_t mVPXImageWrapper;
};
} // namespace mozilla
#endif
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