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/*
* Copyright (C) 2003-2014 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.
*/
/** \file
*
* Internal stuff for the filter core and filter plugins.
*/
#ifndef MPD_FILTER_INTERNAL_HXX
#define MPD_FILTER_INTERNAL_HXX
#include <stddef.h>
struct AudioFormat;
class Error;
template<typename T> struct ConstBuffer;
class Filter {
public:
virtual ~Filter() {}
/**
* Opens the filter, preparing it for FilterPCM().
*
* @param filter the filter object
* @param af the audio format of incoming data; the
* plugin may modify the object to enforce another input
* format
* @param error location to store the error occurring, or nullptr
* to ignore errors.
* @return the format of outgoing data or
* AudioFormat::Undefined() on error
*/
virtual AudioFormat Open(AudioFormat &af, Error &error) = 0;
/**
* Closes the filter. After that, you may call Open() again.
*/
virtual void Close() = 0;
/**
* Filters a block of PCM data.
*
* @param filter the filter object
* @param src the input buffer
* @param error location to store the error occurring, or nullptr
* to ignore errors.
* @return the destination buffer on success (will be
* invalidated by Close() or FilterPCM()), nullptr on
* error
*/
virtual ConstBuffer<void> FilterPCM(ConstBuffer<void> src, Error &error) = 0;
};
#endif
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