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/*
* Copyright 2003-2018 The Music Player Daemon Project
* http://www.musicpd.org
*
* 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 MPD_PCM_RESAMPLER_HXX
#define MPD_PCM_RESAMPLER_HXX
#include "util/ConstBuffer.hxx"
#include "util/Compiler.h"
struct AudioFormat;
/**
* This is an interface for plugins that convert PCM data to a
* specific sample rate.
*/
class PcmResampler {
public:
virtual ~PcmResampler() {}
/**
* Opens the resampler, preparing it for Resample().
*
* Throws std::runtime_error on error.
*
* @param af the audio format of incoming data; the plugin may
* modify the object to enforce another input format (however,
* it may not request a different input sample rate)
* @param new_sample_rate the requested output sample rate
* @param error location to store the error
* @return the format of outgoing data
*/
virtual AudioFormat Open(AudioFormat &af,
unsigned new_sample_rate) = 0;
/**
* Closes the resampler. After that, you may call Open()
* again.
*/
virtual void Close() noexcept = 0;
/**
* Reset the filter's state, e.g. drop/flush buffers.
*/
virtual void Reset() noexcept {
}
/**
* Resamples a block of PCM data.
*
* Throws std::runtime_error on error.
*
* @param src the input buffer
* @return the destination buffer (will be invalidated by
* filter_close() or filter_filter())
*/
virtual ConstBuffer<void> Resample(ConstBuffer<void> src) = 0;
/**
* Flush pending data and return it. This should be called
* repepatedly until it returns nullptr.
*/
virtual ConstBuffer<void> Flush() {
return nullptr;
}
};
#endif
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