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    /*
     * Copyright (c) 2012 Justin Ruggles <justin.ruggles@gmail.com>
     *
     * This file is part of Libav.
     *
     * Libav 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.
     *
     * Libav 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 Libav; if not, write to the Free Software
     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
     */
    
    #ifndef AVRESAMPLE_AUDIO_MIX_H
    #define AVRESAMPLE_AUDIO_MIX_H
    
    #include <stdint.h>
    
    #include "libavutil/samplefmt.h"
    #include "avresample.h"
    #include "audio_data.h"
    
    typedef void (mix_func)(uint8_t **src, void **matrix, int len, int out_ch,
                            int in_ch);
    
    typedef struct AudioMix {
        AVAudioResampleContext *avr;
        enum AVSampleFormat fmt;
        enum AVMixCoeffType coeff_type;
        uint64_t in_layout;
        uint64_t out_layout;
        int in_channels;
        int out_channels;
    
        int ptr_align;
        int samples_align;
        int has_optimized_func;
        const char *func_descr;
        const char *func_descr_generic;
        mix_func *mix;
        mix_func *mix_generic;
    
    
        int16_t *matrix_q8[AVRESAMPLE_MAX_CHANNELS];
    
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        int32_t *matrix_q15[AVRESAMPLE_MAX_CHANNELS];
        float   *matrix_flt[AVRESAMPLE_MAX_CHANNELS];
        void   **matrix;
    } AudioMix;
    
    /**
     * Set mixing function if the parameters match.
     *
     * This compares the parameters of the mixing function to the parameters in the
     * AudioMix context. If the parameters do not match, no changes are made to the
     * active functions. If the parameters do match and the alignment is not
     * constrained, the function is set as the generic mixing function. If the
     * parameters match and the alignment is constrained, the function is set as
     * the optimized mixing function.
     *
     * @param am             AudioMix context
     * @param fmt            input/output sample format
     * @param coeff_type     mixing coefficient type
     * @param in_channels    number of input channels, or 0 for any number of channels
     * @param out_channels   number of output channels, or 0 for any number of channels
     * @param ptr_align      buffer pointer alignment, in bytes
     * @param sample_align   buffer size alignment, in samples
     * @param descr          function type description (e.g. "C" or "SSE")
     * @param mix_func       mixing function pointer
     */
    void ff_audio_mix_set_func(AudioMix *am, enum AVSampleFormat fmt,
                               enum AVMixCoeffType coeff_type, int in_channels,
                               int out_channels, int ptr_align, int samples_align,
                               const char *descr, void *mix_func);
    
    /**
     * Initialize the AudioMix context in the AVAudioResampleContext.
     *
     * The parameters in the AVAudioResampleContext are used to initialize the
     * AudioMix context and set the mixing matrix.
     *
     * @param avr  AVAudioResampleContext
     * @return     0 on success, negative AVERROR code on failure
     */
    int ff_audio_mix_init(AVAudioResampleContext *avr);
    
    /**
     * Close an AudioMix context.
     *
     * This clears and frees the mixing matrix arrays.
     */
    void ff_audio_mix_close(AudioMix *am);
    
    /**
     * Apply channel mixing to audio data using the current mixing matrix.
     */
    int ff_audio_mix(AudioMix *am, AudioData *src);
    
    /* arch-specific initialization functions */
    
    void ff_audio_mix_init_x86(AudioMix *am);
    
    #endif /* AVRESAMPLE_AUDIO_MIX_H */