freesurround.h

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/*
Copyright (C) 2007 Christian Kothe, Mark Spieth
 
This program 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.
 
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
*/
 
#ifndef FREESURROUND_H
#define FREESURROUND_H
 
#include <cstdint>
#include <numbers>
 
using uint = unsigned int;
 
static constexpr uint16_t SURROUND_BUFSIZE { 8192 };
 
class FreeSurround
{
public:
    enum SurroundMode : std::uint8_t
    {
        SurroundModePassive,
        SurroundModeActiveSimple,
        SurroundModeActiveLinear,
        SurroundModePassiveHall
    };
public:
    FreeSurround(uint srate, bool moviemode, SurroundMode mode);
    ~FreeSurround();
 
    // put frames in buffer, returns number of frames used
    uint putFrames(void* buffer, uint numFrames, uint numChannels);
    // get a number of frames
    uint receiveFrames(void *buffer, uint maxFrames);
    // flush unprocessed samples
    void flush();
    uint numUnprocessedFrames() const;
    uint numFrames() const;
 
    long long getLatency();
    uint frameLatency() const;
 
    static uint framesPerBlock();
 
protected:
    void process_block();
    void open();
    void close();
    void SetParams();
 
private:
 
    // the changeable parameters
    struct fsurround_params {
        int32_t center_width { 100 };   // presence of the center channel
        int32_t dimension {      0 };   // dimension
        float   coeff_a   { std::numbers::sqrt2 /
                            std::numbers::sqrt3 };     // surround mixing coefficients
        float   coeff_b   { std::numbers::inv_sqrt3 }; // surround mixing coefficients
        int32_t phasemode {      0 };   // phase shifting mode
        int32_t steering  {      1 };   // steering mode (0=simple, 1=linear)
        int32_t front_sep {    100 };   // front stereo separation
        int32_t rear_sep  {    100 };   // rear stereo separation
    } m_params;
 
    // additional settings
    uint m_srate;
 
    // info about the current setup
    struct buffers          *m_bufs    {nullptr}; // our buffers
    class fsurround_decoder *m_decoder {nullptr}; // the surround decoder
    int  m_inCount                     {0};       // amount in lt,rt
    int  m_outCount                    {0};       // amount in output bufs
    bool m_processed                   {true};    // whether processing is enabled for latency calc
    int  m_processedSize               {0};       // amount processed
    SurroundMode m_surroundMode {SurroundModePassive}; // 1 of 3 surround modes supported
    int m_latencyFrames                {0};       // number of frames of incurred latency
    int m_channels                     {0};
};
 
#endif