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OpusTrackEncoder.h (3216B)

      1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
      2 /* This Source Code Form is subject to the terms of the Mozilla Public
      3 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
      4 * You can obtain one at http://mozilla.org/MPL/2.0/. */
      5 
      6 #ifndef OpusTrackEncoder_h_
      7 #define OpusTrackEncoder_h_
      8 
      9 #include <speex/speex_resampler.h>
     10 #include <stdint.h>
     11 
     12 #include "TimeUnits.h"
     13 #include "TrackEncoder.h"
     14 
     15 struct OpusEncoder;
     16 
     17 namespace mozilla {
     18 
     19 // Opus meta data structure
     20 class OpusMetadata : public TrackMetadataBase {
     21 public:
     22  // The ID Header of OggOpus. refer to http://wiki.xiph.org/OggOpus.
     23  nsTArray<uint8_t> mIdHeader;
     24  // The Comment Header of OggOpus.
     25  nsTArray<uint8_t> mCommentHeader;
     26  int32_t mChannels;
     27  float mSamplingFrequency;
     28  MetadataKind GetKind() const override { return METADATA_OPUS; }
     29 };
     30 
     31 class OpusTrackEncoder : public AudioTrackEncoder {
     32 public:
     33  OpusTrackEncoder(TrackRate aTrackRate,
     34                   MediaQueue<EncodedFrame>& aEncodedDataQueue);
     35  virtual ~OpusTrackEncoder();
     36 
     37  already_AddRefed<TrackMetadataBase> GetMetadata() override;
     38 
     39  /**
     40   * The encoder lookahead at 48k rate.
     41   */
     42  int GetLookahead() const;
     43 
     44 protected:
     45  /**
     46   * The number of frames, in the input rate mTrackRate, needed to fill an
     47   * encoded opus packet. A frame is a sample per channel.
     48   */
     49  int NumInputFramesPerPacket() const override;
     50 
     51  nsresult Init(int aChannels) override;
     52 
     53  /**
     54   * Encodes buffered data and pushes it to mEncodedDataQueue.
     55   */
     56  nsresult Encode(AudioSegment* aSegment) override;
     57 
     58  /**
     59   * The number of frames, in the output rate (see GetOutputSampleRate), needed
     60   * to fill an encoded opus packet. A frame is a sample per channel.
     61   */
     62  int NumOutputFramesPerPacket() const;
     63 
     64  /**
     65   * True if the input needs to be resampled to be fed to the underlying opus
     66   * encoder.
     67   */
     68  bool NeedsResampler() const;
     69 
     70 public:
     71  /**
     72   * Get the samplerate of the data to be fed to the Opus encoder. This might be
     73   * different from the input samplerate if resampling occurs.
     74   */
     75  const TrackRate mOutputSampleRate;
     76 
     77 private:
     78  /**
     79   * The Opus encoder from libopus.
     80   */
     81  OpusEncoder* mEncoder;
     82 
     83  /**
     84   * Total samples of delay added by codec (in rate mOutputSampleRate), can
     85   * be queried by the encoder. From the perspective of decoding, real data
     86   * begins this many samples late, so the encoder needs to append this many
     87   * null samples to the end of stream, in order to align the time of input and
     88   * output.
     89   */
     90  int mLookahead;
     91 
     92  /**
     93   * Number of mLookahead samples that has been written. When non-zero and equal
     94   * to mLookahead, encoding is complete.
     95   */
     96  int mLookaheadWritten;
     97 
     98  /**
     99   * If the input sample rate does not divide 48kHz evenly, the input data are
    100   * resampled.
    101   */
    102  SpeexResamplerState* mResampler;
    103 
    104  /**
    105   * Store the resampled frames that don't fit into an Opus packet duration.
    106   * They will be prepended to the resampled frames next encoding cycle.
    107   */
    108  nsTArray<AudioDataValue> mResampledLeftover;
    109 
    110  /**
    111   * Number of audio frames encoded, in kOpusSamplingRate.
    112   */
    113  uint64_t mNumOutputFrames;
    114 };
    115 
    116 }  // namespace mozilla
    117 
    118 #endif