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/*
* Copyright (c) 2019 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_VP8_FRAME_BUFFER_CONTROLLER_H_
#define API_VIDEO_CODECS_VP8_FRAME_BUFFER_CONTROLLER_H_
#include <memory>
#include <vector>
#include "api/video_codecs/video_codec.h"
#include "api/video_codecs/vp8_frame_config.h"
namespace webrtc {
// Some notes on the prerequisites of the TemporalLayers interface.
// * Vp8FrameBufferController is not thread safe, synchronization is the
// caller's responsibility.
// * The encoder is assumed to encode all frames in order, and callbacks to
// PopulateCodecSpecific() / FrameEncoded() must happen in the same order.
//
// This means that in the case of pipelining encoders, it is OK to have a chain
// of calls such as this:
// - UpdateLayerConfig(timestampA)
// - UpdateLayerConfig(timestampB)
// - PopulateCodecSpecific(timestampA, ...)
// - UpdateLayerConfig(timestampC)
// - OnEncodeDone(timestampA, 1234, ...)
// - UpdateLayerConfig(timestampC)
// - OnEncodeDone(timestampB, 0, ...)
// - OnEncodeDone(timestampC, 1234, ...)
// Note that UpdateLayerConfig() for a new frame can happen before
// FrameEncoded() for a previous one, but calls themselves must be both
// synchronized (e.g. run on a task queue) and in order (per type).
struct CodecSpecificInfo;
struct Vp8EncoderConfig {
static constexpr size_t kMaxPeriodicity = 16;
static constexpr size_t kMaxLayers = 5;
// Number of active temporal layers. Set to 0 if not used.
uint32_t ts_number_layers;
// Arrays of length |ts_number_layers|, indicating (cumulative) target bitrate
// and rate decimator (e.g. 4 if every 4th frame is in the given layer) for
// each active temporal layer, starting with temporal id 0.
uint32_t ts_target_bitrate[kMaxLayers];
uint32_t ts_rate_decimator[kMaxLayers];
// The periodicity of the temporal pattern. Set to 0 if not used.
uint32_t ts_periodicity;
// Array of length |ts_periodicity| indicating the sequence of temporal id's
// to assign to incoming frames.
uint32_t ts_layer_id[kMaxPeriodicity];
// Target bitrate, in bps.
uint32_t rc_target_bitrate;
// Clamp QP to min/max. Use 0 to disable clamping.
uint32_t rc_min_quantizer;
uint32_t rc_max_quantizer;
};
// This interface defines a way of delegating the logic of buffer management.
// Multiple streams may be controlled by a single controller, demuxing between
// them using stream_index.
class Vp8FrameBufferController {
public:
virtual ~Vp8FrameBufferController() = default;
// Number of streamed controlled by |this|.
virtual size_t StreamCount() const = 0;
// If this method returns true, the encoder is free to drop frames for
// instance in an effort to uphold encoding bitrate.
// If this return false, the encoder must not drop any frames unless:
// 1. Requested to do so via Vp8FrameConfig.drop_frame
// 2. The frame to be encoded is requested to be a keyframe
// 3. The encoded detected a large overshoot and decided to drop and then
// re-encode the image at a low bitrate. In this case the encoder should
// call OnEncodeDone() once with size = 0 to indicate drop, and then call
// OnEncodeDone() again when the frame has actually been encoded.
virtual bool SupportsEncoderFrameDropping(size_t stream_index) const = 0;
// New target bitrate, per temporal layer.
virtual void OnRatesUpdated(size_t stream_index,
const std::vector<uint32_t>& bitrates_bps,
int framerate_fps) = 0;
// Called by the encoder before encoding a frame. |cfg| contains the current
// configuration. If the TemporalLayers instance wishes any part of that
// to be changed before the encode step, |cfg| should be changed and then
// return true. If false is returned, the encoder will proceed without
// updating the configuration.
virtual bool UpdateConfiguration(size_t stream_index,
Vp8EncoderConfig* cfg) = 0;
// Returns the recommended VP8 encode flags needed, and moves the temporal
// pattern to the next frame.
// The timestamp may be used as both a time and a unique identifier, and so
// the caller must make sure no two frames use the same timestamp.
// The timestamp uses a 90kHz RTP clock.
// After calling this method, first call the actual encoder with the provided
// frame configuration, and then OnEncodeDone() below.
virtual Vp8FrameConfig UpdateLayerConfig(size_t stream_index,
uint32_t rtp_timestamp) = 0;
// Called after the encode step is done. |rtp_timestamp| must match the
// parameter use in the UpdateLayerConfig() call.
// |is_keyframe| must be true iff the encoder decided to encode this frame as
// a keyframe.
// If the encoder decided to drop this frame, |size_bytes| must be set to 0,
// otherwise it should indicate the size in bytes of the encoded frame.
// If |size_bytes| > 0, and |info| is not null, the TemporalLayers
// instance my update |info| with codec specific data such as temporal id.
// Some fields of this struct may have already been populated by the encoder,
// check before overwriting.
// If |size_bytes| > 0, |qp| should indicate the frame-level QP this frame was
// encoded at. If the encoder does not support extracting this, |qp| should be
// set to 0.
virtual void OnEncodeDone(size_t stream_index,
uint32_t rtp_timestamp,
size_t size_bytes,
bool is_keyframe,
int qp,
CodecSpecificInfo* info) = 0;
// Called by the encoder when the packet loss rate changes.
// |packet_loss_rate| runs between 0.0 (no loss) and 1.0 (everything lost).
virtual void OnPacketLossRateUpdate(float packet_loss_rate) = 0;
// Called by the encoder when the round trip time changes.
virtual void OnRttUpdate(int64_t rtt_ms) = 0;
};
// Interface for a factory of Vp8FrameBufferController instances.
class Vp8FrameBufferControllerFactory {
public:
virtual ~Vp8FrameBufferControllerFactory() = default;
virtual std::unique_ptr<Vp8FrameBufferController> Create(
const VideoCodec& codec) = 0;
};
} // namespace webrtc
#endif // API_VIDEO_CODECS_VP8_FRAME_BUFFER_CONTROLLER_H_