tor-browser

packet_buffer.h (5722B)

---

/*
*  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.
*/

#ifndef MODULES_AUDIO_CODING_NETEQ_PACKET_BUFFER_H_
#define MODULES_AUDIO_CODING_NETEQ_PACKET_BUFFER_H_

#include <cstddef>
#include <cstdint>
#include <optional>

#include "modules/audio_coding/neteq/decoder_database.h"
#include "modules/audio_coding/neteq/packet.h"
#include "modules/include/module_common_types_public.h"  // IsNewerTimestamp

namespace webrtc {

class DecoderDatabase;
class StatisticsCalculator;
class TickTimer;

// This is the actual buffer holding the packets before decoding.
class PacketBuffer {
public:
 enum BufferReturnCodes {
   kOK = 0,
   kFlushed,
   kNotFound,
   kBufferEmpty,
   kInvalidPacket,
   kInvalidPointer
 };

 // Constructor creates a buffer which can hold a maximum of
 // `max_number_of_packets` packets.
 PacketBuffer(size_t max_number_of_packets,
              const TickTimer* tick_timer,
              StatisticsCalculator* stats);

 // Deletes all packets in the buffer before destroying the buffer.
 virtual ~PacketBuffer();

 PacketBuffer(const PacketBuffer&) = delete;
 PacketBuffer& operator=(const PacketBuffer&) = delete;

 // Flushes the buffer and deletes all packets in it.
 virtual void Flush();

 // Returns true for an empty buffer.
 virtual bool Empty() const;

 // Inserts `packet` into the buffer. The buffer will take over ownership of
 // the packet object.
 // Returns PacketBuffer::kOK on success, PacketBuffer::kFlushed if the buffer
 // was flushed due to overfilling.
 virtual int InsertPacket(Packet&& packet);

 // Gets the timestamp for the first packet in the buffer and writes it to the
 // output variable `next_timestamp`.
 // Returns PacketBuffer::kBufferEmpty if the buffer is empty,
 // PacketBuffer::kOK otherwise.
 virtual int NextTimestamp(uint32_t* next_timestamp) const;

 // Gets the timestamp for the first packet in the buffer with a timestamp no
 // lower than the input limit `timestamp`. The result is written to the output
 // variable `next_timestamp`.
 // Returns PacketBuffer::kBufferEmpty if the buffer is empty,
 // PacketBuffer::kOK otherwise.
 virtual int NextHigherTimestamp(uint32_t timestamp,
                                 uint32_t* next_timestamp) const;

 // Returns a (constant) pointer to the first packet in the buffer. Returns
 // NULL if the buffer is empty.
 virtual const Packet* PeekNextPacket() const;

 // Extracts the first packet in the buffer and returns it.
 // Returns an empty optional if the buffer is empty.
 virtual std::optional<Packet> GetNextPacket();

 // Discards the first packet in the buffer. The packet is deleted.
 // Returns PacketBuffer::kBufferEmpty if the buffer is empty,
 // PacketBuffer::kOK otherwise.
 virtual int DiscardNextPacket();

 // Discards all packets that are (strictly) older than timestamp_limit,
 // but newer than timestamp_limit - horizon_samples. Setting horizon_samples
 // to zero implies that the horizon is set to half the timestamp range. That
 // is, if a packet is more than 2^31 timestamps into the future compared with
 // timestamp_limit (including wrap-around), it is considered old.
 virtual void DiscardOldPackets(uint32_t timestamp_limit,
                                uint32_t horizon_samples);

 // Discards all packets that are (strictly) older than timestamp_limit.
 virtual void DiscardAllOldPackets(uint32_t timestamp_limit);

 // Removes all packets with a specific payload type from the buffer.
 virtual void DiscardPacketsWithPayloadType(uint8_t payload_type);

 // Returns the number of packets in the buffer, including duplicates and
 // redundant packets.
 virtual size_t NumPacketsInBuffer() const;

 // Returns the number of samples in the buffer, including samples carried in
 // duplicate and redundant packets.
 virtual size_t NumSamplesInBuffer(size_t last_decoded_length) const;

 // Returns the total duration in samples that the packets in the buffer spans
 // across.
 virtual size_t GetSpanSamples(size_t last_decoded_length,
                               size_t sample_rate,
                               bool count_waiting_time) const;

 // Returns true if the packet buffer contains any DTX or CNG packets.
 virtual bool ContainsDtxOrCngPacket(
     const DecoderDatabase* decoder_database) const;

 // Static method returning true if `timestamp` is older than `timestamp_limit`
 // but less than `horizon_samples` behind `timestamp_limit`. For instance,
 // with timestamp_limit = 100 and horizon_samples = 10, a timestamp in the
 // range (90, 100) is considered obsolete, and will yield true.
 // Setting `horizon_samples` to 0 is the same as setting it to 2^31, i.e.,
 // half the 32-bit timestamp range.
 static bool IsObsoleteTimestamp(uint32_t timestamp,
                                 uint32_t timestamp_limit,
                                 uint32_t horizon_samples) {
   return IsNewerTimestamp(timestamp_limit, timestamp) &&
          (horizon_samples == 0 ||
           IsNewerTimestamp(timestamp, timestamp_limit - horizon_samples));
 }

private:
 void LogPacketDiscarded(int codec_level);

 size_t max_number_of_packets_;
 PacketList buffer_;
 const TickTimer* tick_timer_;
 StatisticsCalculator* stats_;
};

}  // namespace webrtc
#endif  // MODULES_AUDIO_CODING_NETEQ_PACKET_BUFFER_H_