view data/fileio/AudioFileReader.h @ 1376:d9511f9e04d7 dev/refactor-piper-related

Introduce some POD structs for describing an external server application and the desired libraries to load from it, and disambiguating between empty list request and invalid list request. This allows for overriding PiperVampPluginFactory behaviour for using a PluginScan to populate the list request.

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Sonic Visualiser
    An audio file viewer and annotation editor.
    Centre for Digital Music, Queen Mary, University of London.
    This file copyright 2006 Chris Cannam.
    
    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 included with this distribution for more information.
*/

#ifndef _AUDIO_FILE_READER_H_
#define _AUDIO_FILE_READER_H_

#include <QString>

#include "base/BaseTypes.h"
#include "FileSource.h"

#include <vector>
#include <map>

class AudioFileReader : public QObject
{
    Q_OBJECT

public:
    virtual ~AudioFileReader() { }

    /**
     * Return true if the file was opened successfully and no error
     * has subsequently occurred.
     */
    bool isOK() const { return (m_channelCount > 0); }

    /**
     * If isOK() is false, return an error string.
     */
    virtual QString getError() const { return ""; }

    /**
     * Return the number of audio sample frames (i.e. samples per
     * channel) in the file.
     */
    sv_frame_t getFrameCount() const { return m_frameCount; }

    /**
     * Return the number of channels in the file.
     */
    int getChannelCount() const { return m_channelCount; }

    /**
     * Return the samplerate at which the file is being read. This is
     * the rate requested when the file was opened, which may differ
     * from the native rate of the file (in which case the file will
     * be resampled as it is read).
     */
    sv_samplerate_t getSampleRate() const { return m_sampleRate; }

    /**
     * Return the native samplerate of the file. This will differ from
     * getSampleRate() if the file is being resampled because it was
     * requested to open at a different rate from native.
     */
    virtual sv_samplerate_t getNativeRate() const { return m_sampleRate; }

    /**
     * Return the location of the audio data in the reader (as passed
     * in to the FileSource constructor, for example).
     */
    virtual QString getLocation() const { return ""; }
    
    /**
     * Return the title of the work in the audio file, if known.  This
     * may be implemented by subclasses that support file tagging.
     * This is not the same thing as the file name.
     */
    virtual QString getTitle() const { return ""; }

    /**
     * Return the "maker" of the work in the audio file, if known.
     * This could represent almost anything (band, composer,
     * conductor, artist etc).
     */
    virtual QString getMaker() const { return ""; }

    /**
     * Return the local file path of the audio data. This is the
     * location most likely to contain readable audio data: it may be
     * in a different place or format from the originally specified
     * location, for example if the file has been retrieved and
     * decoded. In some cases there may be no local file path, and
     * this will return "" if there is none.
     */
    virtual QString getLocalFilename() const { return ""; }
    
    typedef std::map<QString, QString> TagMap;
    virtual TagMap getTags() const { return TagMap(); }

    /**
     * Return true if this file supports fast seek and random
     * access. Typically this will be true for uncompressed formats
     * and false for compressed ones.
     */
    virtual bool isQuicklySeekable() const = 0;

    /** 
     * Return interleaved samples for count frames from index start.
     * The resulting vector will contain count * getChannelCount()
     * samples (or fewer if end of file is reached).
     *
     * The subclass implementations of this function must be
     * thread-safe -- that is, safe to call from multiple threads with
     * different arguments on the same object at the same time.
     */
    virtual floatvec_t getInterleavedFrames(sv_frame_t start,
                                            sv_frame_t count) const = 0;

    /**
     * Return de-interleaved samples for count frames from index
     * start.  Implemented in this class (it calls
     * getInterleavedFrames and de-interleaves).  The resulting vector
     * will contain getChannelCount() sample blocks of count samples
     * each (or fewer if end of file is reached).
     */
    virtual std::vector<floatvec_t> getDeInterleavedFrames(sv_frame_t start,
                                                           sv_frame_t count) const;

    // only subclasses that do not know exactly how long the audio
    // file is until it's been completely decoded should implement this
    virtual int getDecodeCompletion() const { return 100; } // %

    virtual bool isUpdating() const { return false; }

signals:
    void frameCountChanged();
    
protected:
    sv_frame_t m_frameCount;
    int m_channelCount;
    sv_samplerate_t m_sampleRate;
};

#endif