AudioEncoder.cpp

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/*
    DiscordCoreAPI, A bot library for Discord, written in C++, and featuring explicit multithreading through the usage of custom, asynchronous C++ CoRoutines.
 
    Copyright 2021, 2022 Chris M. (RealTimeChris)
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.
 
    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
    USA
*/
/// AudioEncoder.cpp - Source file for the audio encoder class.
/// Aug 22, 2021
/// https://discordcoreapi.com
/// \file AudioEncoder.cpp
 
#include <discordcoreapi/AudioEncoder.hpp>
#include <opus/opus.h>
 
namespace DiscordCoreInternal {
 
    void OpusEncoderWrapper::OpusEncoderDeleter::operator()(OpusEncoder* other) noexcept {
        if (other) {
            opus_encoder_destroy(other);
            other = nullptr;
        }
    }
 
    OpusEncoderWrapper::OpusEncoderWrapper() {
        int32_t error{};
        this->ptr.reset(opus_encoder_create(this->sampleRate, this->nChannels, OPUS_APPLICATION_AUDIO, &error));
        auto result = opus_encoder_ctl(this->ptr.get(), OPUS_SET_SIGNAL(OPUS_SIGNAL_MUSIC));
        if (result != OPUS_OK) {
            throw DiscordCoreAPI::DCAException{ "Failed to set the Opus signal type, Reason: " + std::string{ opus_strerror(result) } };
        }
        result = opus_encoder_ctl(this->ptr.get(), OPUS_SET_BITRATE(OPUS_BITRATE_MAX));
        if (result != OPUS_OK) {
            throw DiscordCoreAPI::DCAException{ "Failed to set the Opus bitrate, Reason: " + std::string{ opus_strerror(result) } };
        }
    }
 
    EncoderReturnData OpusEncoderWrapper::encodeData(std::basic_string_view<std::byte> inputFrame) {
        if (inputFrame.size() == 0) {
            return {};
        }
        if (this->encodedData.size() == 0) {
            this->encodedData.resize(this->maxBufferSize);
        }
        size_t sampleCount = inputFrame.size() / 2 / 2;
        int32_t count = opus_encode(this->ptr.get(), reinterpret_cast<const opus_int16*>(inputFrame.data()),
            static_cast<int32_t>(inputFrame.size() / 2 / 2), reinterpret_cast<uint8_t*>(this->encodedData.data()), this->maxBufferSize);
        if (count <= 0) {
            return {};
        }
        EncoderReturnData returnData{};
        returnData.sampleCount = sampleCount;
        returnData.data = std::basic_string_view<std::byte>{ this->encodedData.data(), this->encodedData.size() };
        return returnData;
    }
}