Kwave::RateConverter Class Reference

#include <RateConverter.h>

Inheritance diagram for Kwave::RateConverter:

Collaboration diagram for Kwave::RateConverter:

Public Slots
void	input (Kwave::SampleArray data)
void	setRatio (const QVariant r)

Signals
void	output (Kwave::SampleArray data)
Signals inherited from Kwave::StreamObject
void	attributeChanged (const QVariant value)

Public Member Functions
	RateConverter ()
virtual	~RateConverter () Q_DECL_OVERRIDE
virtual void	goOn () Q_DECL_OVERRIDE
Public Member Functions inherited from Kwave::SampleSource
	SampleSource (QObject *parent=Q_NULLPTR)
virtual	~SampleSource ()
virtual bool	done () const
Public Member Functions inherited from Kwave::StreamObject
	StreamObject (QObject *parent=Q_NULLPTR)
virtual	~StreamObject ()
virtual unsigned int	tracks () const
virtual Kwave::StreamObject *	operator[] (unsigned int track)
virtual unsigned int	tracksOfPort (const char *port) const
virtual Kwave::StreamObject *	port (const char *port, unsigned int track)
virtual unsigned int	blockSize () const
void	setAttribute (const char *attribute, const QVariant &value)

Private Attributes
double	m_ratio
SRC_STATE *	m_converter
QVarLengthArray< float, 65536 >	m_converter_in
QVarLengthArray< float, 65536 >	m_converter_out

Additional Inherited Members
Static Public Member Functions inherited from Kwave::StreamObject
static void	setInteractive (bool interactive)

Detailed Description

Definition at line 36 of file RateConverter.h.

Constructor & Destructor Documentation

RateConverter()

Kwave::RateConverter::RateConverter

(

)

Constructor

Definition at line 26 of file RateConverter.cpp.

References m_converter.

    :Kwave::SampleSource(), m_ratio(1.0), m_converter(Q_NULLPTR),
     m_converter_in(), m_converter_out()
{
    int error = 0;
    m_converter = src_new(SRC_SINC_MEDIUM_QUALITY, 1, &error);
    Q_ASSERT(m_converter);
    if (!m_converter) qWarning("creating converter failed: '%s",
        src_strerror(error));
}

~RateConverter()

Kwave::RateConverter::~RateConverter ( )

virtual

Destructor

Definition at line 38 of file RateConverter.cpp.

References m_converter.

{
    if (m_converter) src_delete(m_converter);
}

Member Function Documentation

goOn()

void Kwave::RateConverter::goOn ( )

virtual

does nothing, processing is done in input()

Implements Kwave::SampleSource.

Definition at line 44 of file RateConverter.cpp.

{
}

input

void Kwave::RateConverter::input ( Kwave::SampleArray  data )

slot

receives input data and also directly does the calculation

Definition at line 49 of file RateConverter.cpp.

References Kwave::SampleArray::constData(), Kwave::SampleArray::data(), float2sample(), Kwave::SampleArray::isEmpty(), m_converter, m_converter_in, m_converter_out, m_ratio, output(), sample2float(), Kwave::SampleArray::size(), and Kwave::toUint().

{
    // shortcut for ratio == 1:1
    if ((m_ratio == 1.0) || data.isEmpty()) {
        emit output(data);
        return;
    }

    // normal processing
    Kwave::SampleArray samples_out;
    const unsigned int in_len = data.size();

    // convert the input buffer into an array of floats
    m_converter_in.resize(in_len);
    float          *f_in = m_converter_in.data();
    const sample_t *s_in = data.constData();
    Q_ASSERT(f_in);
    Q_ASSERT(s_in);

    // work blockwise to allow loop unrolling
    unsigned int remaining = in_len;
    const unsigned int block_size = 16;
    while (remaining >= block_size) {
        for (unsigned int i = 0; i < block_size; i++)
            f_in[i] = sample2float(s_in[i]);
        f_in      += block_size;
        s_in      += block_size;
        remaining -= block_size;
    }
    for (; remaining; remaining--)
        (*f_in++) = sample2float(*(s_in++));

    // prepare the output buffer (estimated size, rounded up)
    // worst case would be factor 2, which means that there was a 100%
    // leftover remaining from the previous pass
    // just for safety we limit the extra output space to some
    // (hopefully) reasonable range between 4096 and 16384
    const unsigned int out_len = Kwave::toUint(
        ceil(static_cast<double>(in_len) * m_ratio)
    );
    const unsigned int extra = qBound<unsigned int>(4096, out_len, 16384);
    m_converter_out.resize(out_len + extra);

    // set up the sample rate converter input
    SRC_DATA src;
    src.data_in           = m_converter_in.data();
    src.data_out          = m_converter_out.data();
    src.input_frames      = in_len;
    src.output_frames     = out_len + extra;
    src.input_frames_used = 0;
    src.output_frames_gen = 0;
    src.end_of_input      = (in_len == 0) ? 1 : 0;
    src.src_ratio         = m_ratio;

    // let the converter run...
    int error = src_process(m_converter, &src);
    if (error) qWarning("SRC error: '%s'", src_strerror(error));
    Q_ASSERT(!error);

    // convert the result back from floats to sample_t
    unsigned int gen = Kwave::toUint(src.output_frames_gen);
    Kwave::SampleArray out(gen);
    const float *f_out = src.data_out;
    sample_t    *s_out = out.data();

    // work blockwise to allow loop unrolling
    remaining = gen;
    while (remaining >= block_size) {
        for (unsigned int i = 0; i < block_size; ++i)
            s_out[i] = float2sample(f_out[i]);
        s_out     += block_size;
        f_out     += block_size;
        remaining -= block_size;
    }
    for (; remaining; remaining--, ++s_out, ++f_out)
        *s_out = float2sample(*f_out);

    emit output(out);
}

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output

void Kwave::RateConverter::output ( Kwave::SampleArray  data )

signal

emits a block with the filtered data

Referenced by input().

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setRatio

void Kwave::RateConverter::setRatio ( const QVariant  r )

slot

Sets the conversion ratio, ((new rate) / (old rate))

Definition at line 130 of file RateConverter.cpp.

References m_ratio.

{
    m_ratio = QVariant(ratio).toDouble();
}

Member Data Documentation

m_converter

SRC_STATE* Kwave::RateConverter::m_converter

private

sample rate converter context for libsamplerate

Definition at line 71 of file RateConverter.h.

Referenced by input(), RateConverter(), and ~RateConverter().

m_converter_in

QVarLengthArray<float, 65536> Kwave::RateConverter::m_converter_in

private

input values for the sample rate converter

Definition at line 74 of file RateConverter.h.

Referenced by input().

m_converter_out

QVarLengthArray<float, 65536> Kwave::RateConverter::m_converter_out

private

output values for the sample rate converter

Definition at line 77 of file RateConverter.h.

Referenced by input().

m_ratio

double Kwave::RateConverter::m_ratio

private

conversion ratio, ((new rate) / (old rate))

Definition at line 68 of file RateConverter.h.

Referenced by input(), and setRatio().

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The documentation for this class was generated from the following files:

• libkwave/modules/RateConverter.h
• libkwave/modules/RateConverter.cpp