84 lines
2.3 KiB
C++
84 lines
2.3 KiB
C++
/*
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* Copyright 2003-2020 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef MPD_PCM_RESAMPLER_HXX
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#define MPD_PCM_RESAMPLER_HXX
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#include "util/ConstBuffer.hxx"
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#include "util/Compiler.h"
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struct AudioFormat;
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/**
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* This is an interface for plugins that convert PCM data to a
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* specific sample rate.
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*/
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class PcmResampler {
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public:
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virtual ~PcmResampler() {}
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/**
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* Opens the resampler, preparing it for Resample().
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*
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* Throws std::runtime_error on error.
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*
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* @param af the audio format of incoming data; the plugin may
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* modify the object to enforce another input format (however,
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* it may not request a different input sample rate)
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* @param new_sample_rate the requested output sample rate
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* @param error location to store the error
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* @return the format of outgoing data
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*/
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virtual AudioFormat Open(AudioFormat &af,
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unsigned new_sample_rate) = 0;
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/**
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* Closes the resampler. After that, you may call Open()
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* again.
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*/
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virtual void Close() noexcept = 0;
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/**
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* Reset the filter's state, e.g. drop/flush buffers.
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*/
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virtual void Reset() noexcept {
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}
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/**
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* Resamples a block of PCM data.
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*
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* Throws std::runtime_error on error.
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*
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* @param src the input buffer
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* @return the destination buffer (will be invalidated by
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* filter_close() or filter_filter())
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*/
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virtual ConstBuffer<void> Resample(ConstBuffer<void> src) = 0;
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/**
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* Flush pending data and return it. This should be called
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* repepatedly until it returns nullptr.
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*/
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virtual ConstBuffer<void> Flush() {
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return nullptr;
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}
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};
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#endif
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