annotate data/fileio/AudioFileReader.h @ 490:c3fb8258e34d

* Make it possible to import an entire session from an RDF document.
  However, at the moment the timings of events appear to be constrained
  by how far the audio decoder has got through its audio file at the
  time the event is queried -- need to investigate.

/* -*- 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 "FileSource.h"

#include <vector>

typedef std::vector<float> SampleBlock;

class AudioFileReader : public QObject
{
    Q_OBJECT

public:
    virtual ~AudioFileReader() { }

    bool isOK() const { return (m_channelCount > 0); }

    virtual QString getError() const { return ""; }

    size_t getFrameCount() const { return m_frameCount; }
    size_t getChannelCount() const { return m_channelCount; }
    size_t getSampleRate() const { return m_sampleRate; }
    size_t getNativeRate() const { return m_sampleRate; } // if resampled

    /**
     * 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 interleaved samples for count frames from index start.
     * The resulting sample block 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 void getInterleavedFrames(size_t start, size_t count,
				      SampleBlock &frames) 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 void getDeInterleavedFrames(size_t start, size_t count,
                                        std::vector<SampleBlock> &frames) 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:
    size_t m_frameCount;
    size_t m_channelCount;
    size_t m_sampleRate;
};

#endif