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      1 /*
      2  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #ifndef WEBRTC_MODULES_AUDIO_CODING_NETEQ_PAYLOAD_SPLITTER_H_
     12 #define WEBRTC_MODULES_AUDIO_CODING_NETEQ_PAYLOAD_SPLITTER_H_
     13 
     14 #include "webrtc/base/constructormagic.h"
     15 #include "webrtc/modules/audio_coding/neteq/packet.h"
     16 
     17 namespace webrtc {
     18 
     19 // Forward declarations.
     20 class DecoderDatabase;
     21 
     22 // This class handles splitting of payloads into smaller parts.
     23 // The class does not have any member variables, and the methods could have
     24 // been made static. The reason for not making them static is testability.
     25 // With this design, the splitting functionality can be mocked during testing
     26 // of the NetEqImpl class.
     27 class PayloadSplitter {
     28  public:
     29   enum SplitterReturnCodes {
     30     kOK = 0,
     31     kNoSplit = 1,
     32     kTooLargePayload = -1,
     33     kFrameSplitError = -2,
     34     kUnknownPayloadType = -3,
     35     kRedLengthMismatch = -4,
     36     kFecSplitError = -5,
     37   };
     38 
     39   PayloadSplitter() {}
     40 
     41   virtual ~PayloadSplitter() {}
     42 
     43   // Splits each packet in |packet_list| into its separate RED payloads. Each
     44   // RED payload is packetized into a Packet. The original elements in
     45   // |packet_list| are properly deleted, and replaced by the new packets.
     46   // Note that all packets in |packet_list| must be RED payloads, i.e., have
     47   // RED headers according to RFC 2198 at the very beginning of the payload.
     48   // Returns kOK or an error.
     49   virtual int SplitRed(PacketList* packet_list);
     50 
     51   // Iterates through |packet_list| and, duplicate each audio payload that has
     52   // FEC as new packet for redundant decoding. The decoder database is needed to
     53   // get information about which payload type each packet contains.
     54   virtual int SplitFec(PacketList* packet_list,
     55                        DecoderDatabase* decoder_database);
     56 
     57   // Checks all packets in |packet_list|. Packets that are DTMF events or
     58   // comfort noise payloads are kept. Except that, only one single payload type
     59   // is accepted. Any packet with another payload type is discarded.
     60   virtual int CheckRedPayloads(PacketList* packet_list,
     61                                const DecoderDatabase& decoder_database);
     62 
     63   // Iterates through |packet_list| and, if possible, splits each audio payload
     64   // into suitable size chunks. The result is written back to |packet_list| as
     65   // new packets. The decoder database is needed to get information about which
     66   // payload type each packet contains.
     67   virtual int SplitAudio(PacketList* packet_list,
     68                          const DecoderDatabase& decoder_database);
     69 
     70  private:
     71   // Splits the payload in |packet|. The payload is assumed to be from a
     72   // sample-based codec.
     73   virtual void SplitBySamples(const Packet* packet,
     74                               size_t bytes_per_ms,
     75                               uint32_t timestamps_per_ms,
     76                               PacketList* new_packets);
     77 
     78   // Splits the payload in |packet|. The payload will be split into chunks of
     79   // size |bytes_per_frame|, corresponding to a |timestamps_per_frame|
     80   // RTP timestamps.
     81   virtual int SplitByFrames(const Packet* packet,
     82                             size_t bytes_per_frame,
     83                             uint32_t timestamps_per_frame,
     84                             PacketList* new_packets);
     85 
     86   RTC_DISALLOW_COPY_AND_ASSIGN(PayloadSplitter);
     87 };
     88 
     89 }  // namespace webrtc
     90 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_PAYLOAD_SPLITTER_H_
     91