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* Copyright (c) 2012 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.
#include <string.h> // Provide access to size_t.
#include <memory>
#include <vector>
#include "webrtc/base/constructormagic.h"
#include "webrtc/modules/audio_coding/neteq/audio_decoder_impl.h"
#include "webrtc/modules/audio_coding/neteq/tick_timer.h"
#include "webrtc/typedefs.h"
namespace webrtc {
// Forward declaration.
class DelayPeakDetector;
class DelayManager {
typedef std::vector<int> IATVector;
// Create a DelayManager object. Notify the delay manager that the packet
// buffer can hold no more than |max_packets_in_buffer| packets (i.e., this
// is the number of packet slots in the buffer). Supply a PeakDetector
// object to the DelayManager.
DelayManager(size_t max_packets_in_buffer,
DelayPeakDetector* peak_detector,
const TickTimer* tick_timer);
virtual ~DelayManager();
// Read the inter-arrival time histogram. Mainly for testing purposes.
virtual const IATVector& iat_vector() const;
// Updates the delay manager with a new incoming packet, with
// |sequence_number| and |timestamp| from the RTP header. This updates the
// inter-arrival time histogram and other statistics, as well as the
// associated DelayPeakDetector. A new target buffer level is calculated.
// Returns 0 on success, -1 on failure (invalid sample rate).
virtual int Update(uint16_t sequence_number,
uint32_t timestamp,
int sample_rate_hz);
// Calculates a new target buffer level. Called from the Update() method.
// Sets target_level_ (in Q8) and returns the same value. Also calculates
// and updates base_target_level_, which is the target buffer level before
// taking delay peaks into account.
virtual int CalculateTargetLevel(int iat_packets);
// Notifies the DelayManager of how much audio data is carried in each packet.
// The method updates the DelayPeakDetector too, and resets the inter-arrival
// time counter. Returns 0 on success, -1 on failure.
virtual int SetPacketAudioLength(int length_ms);
// Resets the DelayManager and the associated DelayPeakDetector.
virtual void Reset();
// Calculates the average inter-arrival time deviation from the histogram.
// The result is returned as parts-per-million deviation from the nominal
// inter-arrival time. That is, if the average inter-arrival time is equal to
// the nominal frame time, the return value is zero. A positive value
// corresponds to packet spacing being too large, while a negative value means
// that the packets arrive with less spacing than expected.
virtual int AverageIAT() const;
// Returns true if peak-mode is active. That is, delay peaks were observed
// recently. This method simply asks for the same information from the
// DelayPeakDetector object.
virtual bool PeakFound() const;
// Reset the inter-arrival time counter to 0.
virtual void ResetPacketIatCount();
// Writes the lower and higher limits which the buffer level should stay
// within to the corresponding pointers. The values are in (fractions of)
// packets in Q8.
virtual void BufferLimits(int* lower_limit, int* higher_limit) const;
// Gets the target buffer level, in (fractions of) packets in Q8. This value
// includes any extra delay set through the set_extra_delay_ms() method.
virtual int TargetLevel() const;
virtual void LastDecoderType(NetEqDecoder decoder_type);
// Accessors and mutators.
// Assuming |delay| is in valid range.
virtual bool SetMinimumDelay(int delay_ms);
virtual bool SetMaximumDelay(int delay_ms);
virtual int least_required_delay_ms() const;
virtual int base_target_level() const;
virtual void set_streaming_mode(bool value);
virtual int last_pack_cng_or_dtmf() const;
virtual void set_last_pack_cng_or_dtmf(int value);
static const int kLimitProbability = 53687091; // 1/20 in Q30.
static const int kLimitProbabilityStreaming = 536871; // 1/2000 in Q30.
static const int kMaxStreamingPeakPeriodMs = 600000; // 10 minutes in ms.
static const int kCumulativeSumDrift = 2; // Drift term for cumulative sum
// |iat_cumulative_sum_|.
// Steady-state forgetting factor for |iat_vector_|, 0.9993 in Q15.
static const int kIatFactor_ = 32745;
static const int kMaxIat = 64; // Max inter-arrival time to register.
// Sets |iat_vector_| to the default start distribution and sets the
// |base_target_level_| and |target_level_| to the corresponding values.
void ResetHistogram();
// Updates |iat_cumulative_sum_| and |max_iat_cumulative_sum_|. (These are
// used by the streaming mode.) This method is called by Update().
void UpdateCumulativeSums(int packet_len_ms, uint16_t sequence_number);
// Updates the histogram |iat_vector_|. The probability for inter-arrival time
// equal to |iat_packets| (in integer packets) is increased slightly, while
// all other entries are decreased. This method is called by Update().
void UpdateHistogram(size_t iat_packets);
// Makes sure that |target_level_| is not too large, taking
// |max_packets_in_buffer_| and |extra_delay_ms_| into account. This method is
// called by Update().
void LimitTargetLevel();
bool first_packet_received_;
const size_t max_packets_in_buffer_; // Capacity of the packet buffer.
IATVector iat_vector_; // Histogram of inter-arrival times.
int iat_factor_; // Forgetting factor for updating the IAT histogram (Q15).
const TickTimer* tick_timer_;
// Time elapsed since last packet.
std::unique_ptr<TickTimer::Stopwatch> packet_iat_stopwatch_;
int base_target_level_; // Currently preferred buffer level before peak
// detection and streaming mode (Q0).
// TODO(turajs) change the comment according to the implementation of
// minimum-delay.
int target_level_; // Currently preferred buffer level in (fractions)
// of packets (Q8), before adding any extra delay.
int packet_len_ms_; // Length of audio in each incoming packet [ms].
bool streaming_mode_;
uint16_t last_seq_no_; // Sequence number for last received packet.
uint32_t last_timestamp_; // Timestamp for the last received packet.
int minimum_delay_ms_; // Externally set minimum delay.
int least_required_delay_ms_; // Smallest preferred buffer level (same unit
// as |target_level_|), before applying
// |minimum_delay_ms_| and/or |maximum_delay_ms_|.
int maximum_delay_ms_; // Externally set maximum allowed delay.
int iat_cumulative_sum_; // Cumulative sum of delta inter-arrival times.
int max_iat_cumulative_sum_; // Max of |iat_cumulative_sum_|.
// Time elapsed since maximum was observed.
std::unique_ptr<TickTimer::Stopwatch> max_iat_stopwatch_;
DelayPeakDetector& peak_detector_;
int last_pack_cng_or_dtmf_;
} // namespace webrtc