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/*
* Copyright 2003-2021 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_ENCODER_INTERFACE_HXX
#define MPD_ENCODER_INTERFACE_HXX
#include "EncoderPlugin.hxx"
#include "util/Compiler.h"
#include <cassert>
#include <cstddef>
struct AudioFormat;
struct Tag;
class Encoder {
const bool implements_tag;
public:
explicit Encoder(bool _implements_tag) noexcept
:implements_tag(_implements_tag) {}
virtual ~Encoder() noexcept {}
bool ImplementsTag() const noexcept {
return implements_tag;
}
/**
* Ends the stream: flushes the encoder object, generate an
* end-of-stream marker (if applicable), make everything which
* might currently be buffered available by encoder_read().
*
* After this function has been called, the encoder may not be
* usable for more data, and only Read() and Close() can be
* called.
*
* Throws on error.
*/
virtual void End() {
}
/**
* Flushes an encoder object, make everything which might
* currently be buffered available by Read().
*
* Throws on error.
*/
virtual void Flush() {
}
/**
* Prepare for sending a tag to the encoder. This is used by
* some encoders to flush the previous sub-stream, in
* preparation to begin a new one.
*
* Throws on error.
*/
virtual void PreTag() {
}
/**
* Sends a tag to the encoder.
*
* Instructions: call PreTag(); then obtain flushed data with
* Read(); finally call Tag().
*
* Throws on error.
*
* @param tag the tag object
*/
virtual void SendTag([[maybe_unused]] const Tag &tag) {
}
/**
* Writes raw PCM data to the encoder.
*
* Throws on error.
*
* @param data the buffer containing PCM samples
* @param length the length of the buffer in bytes
*/
virtual void Write(const void *data, size_t length) = 0;
/**
* Reads encoded data from the encoder.
*
* Call this repeatedly until no more data is returned.
*
* @param dest the destination buffer to copy to
* @param length the maximum length of the destination buffer
* @return the number of bytes written to #dest
*/
virtual size_t Read(void *dest, size_t length) = 0;
};
class PreparedEncoder {
public:
virtual ~PreparedEncoder() noexcept {}
/**
* Opens the object. You must call this prior to using it.
* Before you free it, you must call Close(). You may open
* and close (reuse) one encoder any number of times.
*
* After this function returns successfully and before the
* first encoder_write() call, you should invoke
* encoder_read() to obtain the file header.
*
* Throws on error.
*
* @param audio_format the encoder's input audio format; the plugin
* may modify the struct to adapt it to its abilities
*/
virtual Encoder *Open(AudioFormat &audio_format) = 0;
/**
* Get mime type of encoded content.
*
* @return an constant string, nullptr on failure
*/
virtual const char *GetMimeType() const noexcept {
return nullptr;
}
};
#endif