downmix.hxx

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/*
 * Copyright (C) 2024-2026 David C. Manuelda (StormBytePP)
 *
 * This file is part of StormByte-Multimedia.
 *
 * StormByte-Multimedia original source is dual-licensed:
 *
 * 1. GNU Lesser General Public License v3.0 (or later)
 *    You may redistribute and/or modify this file under the terms of the
 *    GNU Lesser General Public License as published by the Free Software
 *    Foundation, either version 3 of the License, or (at your option)
 *    any later version.
 *
 * 2. Commercial license
 *    Alternatively, this file may be used under the terms of a commercial
 *    license agreement with the copyright holder
 *    (David C. Manuelda <StormByte@gmail.com>).
 *
 * Both licenses apply only to original StormByte-Multimedia source in this
 * file. Third-party components — including FFmpeg and embedded trained data —
 * remain under their own licenses and are not covered by the commercial grant.
 *
 * Neither license grants any patent rights. Any patent licenses required
 * to use this software or third-party components must be obtained separately
 * from the patent holders.
 *
 * StormByte-Multimedia 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
 * version 3 along with StormByte-Multimedia. If not, see
 * <https://www.gnu.org/licenses/lgpl-3.0.html>.
 *
 * SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-StormByte-Commercial
 */
 
#pragma once
 
#include <StormByte/logger/log.hxx>
#include <StormByte/multimedia/ffmpeg/AVFilterGraph.hxx>
#include <StormByte/multimedia/pipeline/filters/ffmpeg.hxx>
#include <StormByte/multimedia/property/channel_layout.hxx>
#include <StormByte/multimedia/visibility.h>
 
#include <memory>
#include <string>
#include <string_view>

namespace StormByte::Multimedia::Pipeline::Filter::Audio {
    class STORMBYTE_MULTIMEDIA_PUBLIC Downmix: public Filter::Process {
        public:
            Downmix(std::shared_ptr<StormByte::Logger::Log> log,
                Property::ChannelLayout target) noexcept;

            Downmix(const Downmix& other) = delete;

            Downmix(Downmix&& other) noexcept = delete;

            ~Downmix() noexcept override = default;

            Downmix& operator=(const Downmix& other) = delete;

            Downmix& operator=(Downmix&& other) noexcept = delete;

            enum StormByte::Multimedia::Type Media() const noexcept override;

            void Clean() noexcept override;

            void Setup() noexcept override;

            void Process(const Pipeline::Frame& frame) noexcept override;

            void Eof() noexcept override;
 
        private:
            std::string_view LayoutName() const noexcept;

            std::string AformatChain() const noexcept;

            std::string PanChain() const noexcept;

            bool EnsureGraph(const StormByte::Multimedia::FFmpeg::AVFrame& src,
                std::string_view chain) noexcept;
 
            Property::ChannelLayout m_target;   
            std::unique_ptr<StormByte::Multimedia::FFmpeg::AVFilterGraph> m_graph;  
            bool m_pan = false;                 
    };
}