view audio/PlaySpeedRangeMapper.cpp @ 570:6f54789f3127 3.0-integration

Fix race condition in first-time recording, where adding the recording wave model would prompt the audio play source to note that its channel count had increased (from 0 to, say, 2) and thus to cause the audio device to be reopened, stopping recording. Fix is to make this only happen if channel count increases beyond that of the device, which shouldn't happen in the recording case

/* -*- 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 QMUL.
    
    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.
*/

#include "PlaySpeedRangeMapper.h"

#include <iostream>
#include <cmath>

// PlaySpeedRangeMapper maps a position in the range [0,120] on to a
// play speed factor on a logarithmic scale in the range 0.125 ->
// 8. This ensures that the desirable speed factors 0.25, 0.5, 1, 2,
// and 4 are all mapped to exact positions (respectively 20, 40, 60,
// 80, 100).

// Note that the "factor" referred to below is a play speed factor
// (higher = faster, 1.0 = normal speed), the "value" is a percentage
// (higher = faster, 100 = normal speed), and the "position" is an
// integer step on the dial's scale (0-120, 60 = centre).

PlaySpeedRangeMapper::PlaySpeedRangeMapper() :
    m_minpos(0),
    m_maxpos(120)
{
}

int
PlaySpeedRangeMapper::getPositionForValue(double value) const
{
    // value is percent
    double factor = getFactorForValue(value);
    int position = getPositionForFactor(factor);
    return position;
}

int
PlaySpeedRangeMapper::getPositionForValueUnclamped(double value) const
{
    // We don't really provide this
    return getPositionForValue(value);
}

double
PlaySpeedRangeMapper::getValueForPosition(int position) const
{
    double factor = getFactorForPosition(position);
    double pc = getValueForFactor(factor);
    return pc;
}

double
PlaySpeedRangeMapper::getValueForPositionUnclamped(int position) const
{
    // We don't really provide this
    return getValueForPosition(position);
}

double
PlaySpeedRangeMapper::getValueForFactor(double factor) const
{
    return factor * 100.0;
}

double
PlaySpeedRangeMapper::getFactorForValue(double value) const
{
    return value / 100.0;
}

int
PlaySpeedRangeMapper::getPositionForFactor(double factor) const
{
    if (factor == 0) return m_minpos;
    int pos = int(lrint((log2(factor) + 3.0) * 20.0));
    if (pos < m_minpos) pos = m_minpos;
    if (pos > m_maxpos) pos = m_maxpos;
    return pos;
}

double
PlaySpeedRangeMapper::getFactorForPosition(int position) const
{
    return pow(2.0, double(position) * 0.05 - 3.0);
}

QString
PlaySpeedRangeMapper::getUnit() const
{
    return "%";
}