sound_asset_writer.h

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/*
    Copyright (C) 2012-2021 Carl Hetherington <cth@carlh.net>
 
    This file is part of libdcp.
 
    libdcp is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
 
    libdcp 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 General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with libdcp.  If not, see <http://www.gnu.org/licenses/>.
 
    In addition, as a special exception, the copyright holders give
    permission to link the code of portions of this program with the
    OpenSSL library under certain conditions as described in each
    individual source file, and distribute linked combinations
    including the two.
 
    You must obey the GNU General Public License in all respects
    for all of the code used other than OpenSSL.  If you modify
    file(s) with this exception, you may extend this exception to your
    version of the file(s), but you are not obligated to do so.  If you
    do not wish to do so, delete this exception statement from your
    version.  If you delete this exception statement from all source
    files in the program, then also delete it here.
*/
 
 
#include "asset_writer.h"
#include "dcp_assert.h"
#include "fsk.h"
#include "sound_asset.h"
#include "sound_frame.h"
#include <memory>
#include <boost/filesystem.hpp>
#include <boost/shared_array.hpp>
 
 
struct sync_test1;
 
 
namespace dcp {
 
 
namespace sound_asset_writer {
 
template <typename T>
int32_t convert(T) { return {}; }
 
template <>
inline int32_t convert(int32_t x)
{
        int constexpr clip = (1 << 23);
        return std::max(-clip, std::min(clip, x));
}
 
template<>
inline int32_t convert(float x)
{
        float constexpr clip = 1.0f - (1.0f / (1 << 23));
        float constexpr scale = (1 << 23);
        auto const clipped = std::max(-clip, std::min(clip, x));
        return std::lround(clipped * scale);
}
 
}
 
 
class SoundAsset;
 
 
class SoundAssetWriter : public AssetWriter
{
public:
        ~SoundAssetWriter();
 
        void write(float const * const * data, int channels, int frames);
 
        void write(int32_t const * const * data, int channels, int frames);
 
        bool finalize () override;
 
private:
        friend class SoundAsset;
        friend struct ::sync_test1;
 
        byte_t* frame_buffer_data() const;
        int frame_buffer_capacity() const;
 
        template <class T>
        void
        do_write(T const * const * data, int data_channels, int frames)
        {
                DCP_ASSERT(!_finalized);
                DCP_ASSERT(frames > 0);
 
                auto const asset_channels = _asset->channels();
                DCP_ASSERT(data_channels <= asset_channels);
 
                if (!_started) {
                        start();
                }
 
                for (int i = 0; i < frames; ++i) {
 
                        auto out = frame_buffer_data() + _frame_buffer_offset;
 
                        /* Write one sample per asset channel */
                        for (int j = 0; j < asset_channels; ++j) {
                                int32_t s = 0;
                                if (j == 13 && _sync) {
                                        s = _fsk.get();
                                } else if (j < data_channels) {
                                        s = sound_asset_writer::convert(data[j][i]);
                                }
                                *out++ = (s & 0xff);
                                *out++ = (s & 0xff00) >> 8;
                                *out++ = (s & 0xff0000) >> 16;
                        }
                        _frame_buffer_offset += 3 * asset_channels;
 
                        DCP_ASSERT(_frame_buffer_offset <= frame_buffer_capacity());
 
                        /* Finish the MXF frame if required */
                        if (_frame_buffer_offset == frame_buffer_capacity()) {
                                write_current_frame();
                                _frame_buffer_offset = 0;
                                memset(frame_buffer_data(), 0, frame_buffer_capacity());
                        }
                }
        }
 
        SoundAssetWriter(SoundAsset *, boost::filesystem::path, std::vector<dcp::Channel> extra_active_channels, bool sync, bool include_mca_subdescriptors);
 
        void start ();
        void write_current_frame ();
        std::vector<bool> create_sync_packets ();
 
        /* do this with an opaque pointer so we don't have to include
           ASDCP headers
        */
 
        struct ASDCPState;
        std::shared_ptr<ASDCPState> _state;
 
        SoundAsset* _asset = nullptr;
        int _frame_buffer_offset = 0;
 
        std::vector<dcp::Channel> _extra_active_channels;
        bool _sync = false;
        int _sync_packet = 0;
        FSK _fsk;
        bool _include_mca_subdescriptors = true;
};
 
}