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/***************************************************************************
PlayBackDevice.h - abstract base class for playback devices
-------------------
begin : Sat May 19 2001
copyright : (C) 2001 by Thomas Eschenbacher
email : Thomas.Eschenbacher@gmx.de
***************************************************************************/
/***************************************************************************
* *
* 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. *
* *
***************************************************************************/
#ifndef PLAY_BACK_DEVICE_H
#define PLAY_BACK_DEVICE_H
#include "config.h"
#include <QList>
#include <QString>
#include <QStringList>
#include "libkwave/Sample.h"
#include "libkwave/String.h"
namespace Kwave
{
class SampleArray;
/**
* Abstract base class for all kinds of playback devices.
* It provides only a minimum of necessary functions, like
* opening/closing and writing samples.
*
* @note this class is not threadsafe on its own, it relies on the
* threadsafe implementation of the PlayBack plugin.
* @note there are no checks for avoiding close without open,
* opening twice or similar
* @note there are no precautions to prevent duplicate instances
*
*/
class PlayBackDevice
{
public:
/** Destructor */
virtual ~PlayBackDevice() {}
/**
* Opens the device for playback.
* @param device name of the output device, this might be a
* file name of a device or any user-defined
* string that tells the playback device where
* to write data.
* @param rate playback rate [samples/second]
* @param channels number of playback channels [1=mono, 2=stereo,...]
* @param bits resolution for output [bits/sample]
* @param bufbase exponent of the buffer size. The real buffer
* size will be (2 ^ bufbase) bytes.
* @return zero-length string if successful, or an error
* message if failed
*/
virtual QString open(const QString &device, double rate,
unsigned int channels, unsigned int bits,
unsigned int bufbase) = 0;
/**
* Writes an array of samples to the output device. Each sample
* in the array is designated to one output channel.
* @param samples array of samples for output
* @return 0 if successful, or an error code if failed
*/
virtual int write(const Kwave::SampleArray &samples) = 0;
/**
* Closes the output device.
*/
virtual int close() = 0;
/** return a string list with supported device names */
virtual QStringList supportedDevices() {
return QStringList();
}
/** return a string suitable for a "File Open..." dialog */
virtual QString fileFilter() { return _(""); }
/**
* returns a list of supported bits per sample resolutions
* of a given device.
*
* @param device filename of the device
* @return list of supported bits per sample, or empty on errors
*/
virtual QList<unsigned int> supportedBits(const QString &device) = 0;
/**
* Detect the minimum and maximum number of channels.
* If the detection fails, minimum and maximum are set to zero.
*
* @param device filename of the device
* @param min receives the lowest supported number of channels
* @param max receives the highest supported number of channels
* @return zero or positive number if ok,
* negative error number if failed
*/
virtual int detectChannels(const QString &device,
unsigned int &min, unsigned int &max)
{
Q_UNUSED(device)
return min = max = 0;
}
};
}
#endif /* PLAY_BACK_DEVICE_H */
//***************************************************************************
//***************************************************************************
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