view data/fileio/AudioFileReader.h @ 1833:21c792334c2e sensible-delimited-data-strings

Rewrite all the DelimitedDataString stuff so as to return vectors of individual cell strings rather than having the classes add the delimiters themselves. Rename accordingly to names based on StringExport. Take advantage of this in the CSV writer code so as to properly quote cells that contain delimiter characters.

/* -*- 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