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// Copyright 2020 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MEDIA_AUDIO_AUDIO_OPUS_ENCODER_H_
#define MEDIA_AUDIO_AUDIO_OPUS_ENCODER_H_
#include <memory>
#include <vector>
#include "media/base/audio_bus.h"
#include "media/base/audio_converter.h"
#include "media/base/audio_encoder.h"
#include "media/base/audio_timestamp_helper.h"
#include <opus/opus.h>
namespace media {
class ChannelMixer;
class ConvertingAudioFifo;
using OpusEncoderDeleterType = void (*)(OpusEncoder* encoder_ptr);
using OwnedOpusEncoder = std::unique_ptr<OpusEncoder, OpusEncoderDeleterType>;
// Performs Opus encoding of the input audio. The input audio is converted to a
// a format suitable for Opus before it is passed to the libopus encoder
// instance to do the actual encoding.
class MEDIA_EXPORT AudioOpusEncoder : public AudioEncoder {
public:
AudioOpusEncoder();
AudioOpusEncoder(const AudioOpusEncoder&) = delete;
AudioOpusEncoder& operator=(const AudioOpusEncoder&) = delete;
~AudioOpusEncoder() override;
// AudioEncoder:
void Initialize(const Options& options,
OutputCB output_callback,
EncoderStatusCB done_cb) override;
void Encode(std::unique_ptr<AudioBus> audio_bus,
base::TimeTicks capture_time,
EncoderStatusCB done_cb) override;
void Flush(EncoderStatusCB done_cb) override;
static constexpr int kMinBitrate = 6000;
private:
friend class AudioEncodersTest;
// Calls libopus to do actual encoding.
void DoEncode(const AudioBus* audio_bus);
void DrainFifoOutput();
CodecDescription PrepareExtraData();
EncoderStatus::Or<OwnedOpusEncoder> CreateOpusEncoder(
const std::optional<AudioEncoder::OpusOptions>& opus_options);
AudioParameters input_params_;
// Output parameters after audio conversion. This may differ from the input
// params in the number of channels, sample rate, and the frames per buffer.
// (See CreateOpusInputParams() in the .cc file for details).
AudioParameters converted_params_;
std::unique_ptr<ConvertingAudioFifo> fifo_;
bool fifo_has_data_ = false;
// Used to mix incoming Encode() buffers to match the expect input channel
// count.
std::unique_ptr<ChannelMixer> mixer_;
AudioParameters mixer_input_params_;
// Buffer for passing AudioBus data from the converter to the encoder.
std::vector<float> buffer_;
// The actual libopus encoder instance. This is nullptr if creating the
// encoder fails.
OwnedOpusEncoder opus_encoder_;
// Keeps track of the timestamps for the each |output_callback_|
std::unique_ptr<AudioTimestampHelper> timestamp_tracker_;
// Callback for reporting completion and status of the current Flush() or
// Encoder()
EncoderStatusCB current_done_cb_;
// Recommended value for opus_encode_float(), according to documentation in
// third_party/opus/src/include/opus.h, so that the Opus encoder does not
// degrade the audio due to memory constraints, and is independent of the
// duration of the encoded buffer.
static inline constexpr int kOpusMaxDataBytes = 4000;
// Fixed size buffer that all frames are encoded too. Most encoded data is
// generally only a few hundred bytes, so we copy out from this buffer when
// vending encoded packets.
std::array<uint8_t, kOpusMaxDataBytes> encoding_buffer_;
// True if the next output needs to have extra_data in it, only happens once.
bool need_to_emit_extra_data_ = true;
};
} // namespace media
#endif // MEDIA_AUDIO_AUDIO_OPUS_ENCODER_H_
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