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k3b/libk3b/plugin/k3baudioencoder.h

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/*
*
* $Id: k3baudioencoder.h 619556 2007-01-03 17:38:12Z trueg $
* Copyright (C) 2003 Sebastian Trueg <trueg@k3b.org>
*
* This file is part of the K3b project.
* Copyright (C) 1998-2007 Sebastian Trueg <trueg@k3b.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.
* See the file "COPYING" for the exact licensing terms.
*/
#ifndef _K3B_AUDIO_ENCODER_H_
#define _K3B_AUDIO_ENCODER_H_
#include <k3bplugin.h>
#include <k3bmsf.h>
#include "k3b_export.h"
/**
* The base class for all audio encoders.
* Do not be alarmed by the number of methods since most of them
* do not need to be touched. They are just there to keep the API
* clean and extendable.
*
* see the skeleton files for further help.
*/
class LIBK3B_EXPORT K3bAudioEncoder : public K3bPlugin
{
Q_OBJECT
public:
K3bAudioEncoder( QObject* parent = 0, const char* name = 0 );
virtual ~K3bAudioEncoder();
// TODO: if the following methods are to be activated the config methods in
// K3bPluginConfigWidget also need to be changed since they do not allow
// to use an extern config object yet.
// Perhaps these two methods should even go into K3bPlugin.
/**
* This calls readConfig using the k3bcore config object
*/
// void readConfig();
/**
* Force the plugin to read it's configuration
*/
// virtual void readConfig( KConfig* );
QString group() const { return "AudioEncoder"; }
/**
* This should return the fileextensions supported by the filetype written in the
* encoder.
* May return an empty list in which case the encoder will not be usable (this may come
* in handy if the encoder is based on some external program or lib which is not
* available on runtime.)
*/
virtual QStringList extensions() const = 0;
/**
* The filetype as presented to the user.
*/
virtual QString fileTypeComment( const QString& extension ) const = 0;
/**
* Determine the filesize of the encoded file (~)
* default implementation returnes -1 (unknown)
* First parameter is the extension to be used
*/
virtual long long fileSize( const QString&, const K3b::Msf& ) const { return -1; }
/**
* The default implementation openes the file for writing with
* writeData. Normally this does not need to be reimplemented.
* @param extension the filetype to be used.
*
*/
virtual bool openFile( const QString& extension, const QString& filename, const K3b::Msf& length );
/**
* The default implementation returnes true if openFile (default implementation) has been
* successfully called. Normally this does not need to be reimplemented but it has to be
* if openFile is reimplemented.
*/
virtual bool isOpen() const;
/**
* The default implementation closes the file opened by openFile
* (default implementation)
* Normally this does not need to be reimplemented but it has to be
* if openFile is reimplemented.
*/
virtual void closeFile();
/**
* The default implementation returnes the filename set in openFile
* or QString::null if no file has been opened.
* Normally this does not need to be reimplemented but it has to be
* if openFile is reimplemented.
*/
virtual const QString& filename() const;
enum MetaDataField {
META_TRACK_TITLE,
META_TRACK_ARTIST,
META_TRACK_COMMENT,
META_TRACK_NUMBER,
META_ALBUM_TITLE,
META_ALBUM_ARTIST,
META_ALBUM_COMMENT,
META_YEAR,
META_GENRE };
/**
* Calling this method does only make sense after successfully
* calling openFile and before calling encode.
* This calls setMetaDataInternal.
*/
void setMetaData( MetaDataField, const QString& );
/**
* Returnes the amount of actually written bytes or -1 if an error
* occurred.
*
* Be aware that the returned amount of written data may very well differ
* from len since the data is encoded.
*/
long encode( const char*, Q_ULONG len );
/**
* Use this signal in case of an error to provide the user with information
* about the problem.
*/
virtual QString lastErrorString() const;
protected:
/**
* Called by the default implementation of openFile
* This calls initEncoderInternal.
*/
bool initEncoder( const QString& extension, const K3b::Msf& length );
/**
* Called by the deafult implementation of openFile
* This calls finishEncoderInternal.
*/
void finishEncoder();
/**
* Use this to write the data to the file when
* using the default implementation of openFile
* Returnes the number of bytes actually written.
*/
Q_LONG writeData( const char*, Q_ULONG len );
/**
* initzialize the decoder structures.
* default implementation does nothing
* this may already write data.
*/
virtual bool initEncoderInternal( const QString& extension, const K3b::Msf& length );
/**
* reimplement this if the encoder needs to do some
* finishing touch.
*/
virtual void finishEncoderInternal();
/**
* encode the data and write it with writeData (when using
* the default)
* The data will always be 16bit 44100 Hz stereo little endian samples.
* Should return the amount of actually written bytes (may be 0) and -1
* on error.
*/
// TODO: use Q_INT16* instead of char*
// FIXME: why little endian while CDs use big endian???
virtual long encodeInternal( const char*, Q_ULONG len ) = 0;
/**
* default implementation does nothing
* this may already write data.
*/
virtual void setMetaDataInternal( MetaDataField, const QString& );
/**
* Use this in combination with the default implementation of lastError()
*/
void setLastError( const QString& );
private:
class Private;
Private* d;
};
#endif