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/*
* Copyright (c) 2017 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_CODECS_VIDEO_ENCODER_FACTORY_H_
#define API_VIDEO_CODECS_VIDEO_ENCODER_FACTORY_H_
#include <memory>
#include <string>
#include <vector>
#include "absl/types/optional.h"
#include "api/environment/environment.h"
#include "api/units/data_rate.h"
#include "api/video/render_resolution.h"
#include "api/video_codecs/sdp_video_format.h"
#include "api/video_codecs/video_encoder.h"
namespace webrtc {
// A factory that creates VideoEncoders.
// NOTE: This class is still under development and may change without notice.
class VideoEncoderFactory {
public:
struct CodecSupport {
bool is_supported = false;
bool is_power_efficient = false;
};
// An injectable class that is continuously updated with encoding conditions
// and selects the best encoder given those conditions. An implementation is
// typically stateful to avoid toggling between different encoders, which is
// costly due to recreation of objects, a new codec will always start with a
// key-frame.
class EncoderSelectorInterface {
public:
virtual ~EncoderSelectorInterface() {}
// Informs the encoder selector about which encoder that is currently being
// used.
virtual void OnCurrentEncoder(const SdpVideoFormat& format) = 0;
// Called every time the available bitrate is updated. Should return a
// non-empty if an encoder switch should be performed.
virtual absl::optional<SdpVideoFormat> OnAvailableBitrate(
const DataRate& rate) = 0;
// Called every time the encoder input resolution change. Should return a
// non-empty if an encoder switch should be performed.
virtual absl::optional<SdpVideoFormat> OnResolutionChange(
const RenderResolution& resolution) {
return absl::nullopt;
}
// Called if the currently used encoder reports itself as broken. Should
// return a non-empty if an encoder switch should be performed.
virtual absl::optional<SdpVideoFormat> OnEncoderBroken() = 0;
};
// Returns a list of supported video formats in order of preference, to use
// for signaling etc.
virtual std::vector<SdpVideoFormat> GetSupportedFormats() const = 0;
// Returns a list of supported video formats in order of preference, that can
// also be tagged with additional information to allow the VideoEncoderFactory
// to separate between different implementations when CreateVideoEncoder is
// called.
virtual std::vector<SdpVideoFormat> GetImplementations() const {
return GetSupportedFormats();
}
// Query whether the specifed format is supported or not and if it will be
// power efficient, which is currently interpreted as if there is support for
// hardware acceleration.
// of valid values for `scalability_mode`.
// NOTE: QueryCodecSupport is currently an experimental feature that is
// subject to change without notice.
virtual CodecSupport QueryCodecSupport(
const SdpVideoFormat& format,
absl::optional<std::string> scalability_mode) const {
// Default implementation, query for supported formats and check if the
// specified format is supported. Returns false if scalability_mode is
// specified.
CodecSupport codec_support;
if (!scalability_mode) {
codec_support.is_supported = format.IsCodecInList(GetSupportedFormats());
}
return codec_support;
}
// Creates a VideoEncoder for the specified format.
virtual std::unique_ptr<VideoEncoder> Create(
const Environment& env,
const SdpVideoFormat& format) = 0;
// This method creates a EncoderSelector to use for a VideoSendStream.
// (and hence should probably been called CreateEncoderSelector()).
//
// Note: This method is unsuitable if encoding several streams that
// are using same VideoEncoderFactory (either by several streams in one
// PeerConnection or streams with different PeerConnection but same
// PeerConnectionFactory). This is due to the fact that the method is not
// given any stream identifier, nor is the EncoderSelectorInterface given any
// stream identifiers, i.e one does not know which stream is being encoded
// with help of the selector.
//
// In such scenario, the `RtpSenderInterface::SetEncoderSelector` is
// recommended.
//
// TODO(bugs.webrtc.org:14122): Deprecate and remove in favor of
// `RtpSenderInterface::SetEncoderSelector`.
virtual std::unique_ptr<EncoderSelectorInterface> GetEncoderSelector() const {
return nullptr;
}
virtual ~VideoEncoderFactory() {}
};
} // namespace webrtc
#endif // API_VIDEO_CODECS_VIDEO_ENCODER_FACTORY_H_