view data/fileio/AudioFileReader.h @ 1861:9219834e39a4

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/* -*- 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 SV_AUDIO_FILE_READER_H
#define SV_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). This might be a
     * remote URL.
     *
     * See also getLocalFilename().
     */
    virtual QString getLocation() const = 0;

    /**
     * Return the local file path of the audio data. This is the
     * filesystem location most likely to contain readable audio data,
     * but it may be in a different place or format from the
     * originally specified location - for example, if the file has
     * been retrieved and decoded, then it will be the (possibly
     * temporary) decode target file.
     *
     * This returns a non-empty value only if there is some local
     * filename that contains exactly the audio data being provided by
     * this reader. In some cases this may not exist, for example when
     * a file has been resampled or normalised directly into a memory
     * buffer. In this case, return an empty string.
     *
     * See also getLocation().
     */
    virtual QString getLocalFilename() const = 0;
    
    /**
     * 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 = 0;

    /**
     * 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 = 0;

    /**
     * Return any tag pairs picked up from the audio file. See also
     * getTitle and getMaker, and note that a reader which does not
     * implement getTags may still return values from those.
     */
    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 a percentage value indicating how far through decoding
     * the audio file we are. This should be implemented by subclasses
     * that will not know exactly how long the audio file is (in
     * sample frames) until it has been completely decoded. A reader
     * that initialises the frame count directly within its
     * constructor should always return 100 from this.
    */
    virtual int getDecodeCompletion() const { return 100; }

    /**
     * Return true if decoding is still in progress and the frame
     * count may change.
     */
    virtual bool isUpdating() const { return false; }

    /** 
     * 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;

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

#endif