Audio::Stream Class Reference

#include <Stream.h>

Classes
class	NoBufferException

Public Member Functions
virtual	~Stream ()
const std::string &	getPath () const throw ()
const Format &	getFormat () const throw ()
double	getLength () throw (Exception)
unsigned int	read (void *buffer, unsigned int bufferSize) throw (Exception)
double	getPosition () const throw ()
void	seek (double position) throw (Exception)

Protected Member Functions
	Stream (const std::string &path) throw (Exception)
Format &	getFormatInternal () throw ()
virtual double	getLengthImpl () const =0 throw (Exception)
virtual double	getPositionImpl () const =0 throw ()
virtual void	seekImpl (double position)=0 throw (Exception)
virtual void	getBufferImpl (void *&buffer, unsigned int &bufferSize)=0 throw (Exception)
virtual void	nextBufferImpl ()=0 throw (Exception)

Detailed Description

Stream abstract class

Remarks

This is the interface to all kinds of streams.

This abstract class has but a few

See Also

Codec to create Stream instances.

Definition at line 21 of file Stream.h.

Constructor & Destructor Documentation

Audio::Stream::Stream ( const std::string &  path) throw ( Exception )

protected

Internal constructor used by derived classes

Definition at line 17 of file Stream.cpp.

    {
    }

Audio::Stream::~Stream ( )

virtual

Definition at line 21 of file Stream.cpp.

    {
    }

Member Function Documentation

virtual void Audio::Stream::getBufferImpl ( void *&  buffer, unsigned int &  bufferSize  ) throw ( Exception )

protectedpure virtual

Get the stream's current reading buffer.

Remarks

This buffer is to remain valid until any stream advancement is made through seekImpl or nextBufferImpl, or the object gets destroyed. Repeated getBufferImpl calls will not modify the stream, though internal state may be modified in transparent ways (allowing for lazy decoding). In short, getBufferImpl is an idempotent member function.

Asking the buffer where nextBufferImpl() has never been called would raise

a NoBuffer exception.

const Format& Audio::Stream::getFormat ( ) const throw ( )

inline

Return the format of the stream.

Definition at line 59 of file Stream.h.

{ return streamFormat; }

Format& Audio::Stream::getFormatInternal ( ) throw ( )

inlineprotected

Internal write access to stream format, for derived classes

Definition at line 50 of file Stream.h.

{ return streamFormat; }

double Audio::Stream::getLength	(	)
throw	(	Exception
	)

Return the length of the stream.

Remarks

This may not be an inocuous function. Some codecs can't return the length of a file without parsing it entirely, and as such it cannot be const. So use sparingly.

Definition at line 25 of file Stream.cpp.

References getLengthImpl().

    {
        return getLengthImpl();
    }

virtual double Audio::Stream::getLengthImpl ( ) const throw ( Exception )

protectedpure virtual

See Also

getLength

Referenced by getLength().

const std::string& Audio::Stream::getPath ( ) const throw ( )

inline

Return the path of the associated file.

Definition at line 56 of file Stream.h.

{ return filePath; };

double Audio::Stream::getPosition	(	)		const
throw	(
	)

Get the stream's current position, in seconds

Definition at line 30 of file Stream.cpp.

References getPositionImpl().

    {
        return getPositionImpl();
    }

virtual double Audio::Stream::getPositionImpl ( ) const throw ( )

protectedpure virtual

See Also

getPosition

Referenced by getPosition().

virtual void Audio::Stream::nextBufferImpl ( ) throw ( Exception )

protectedpure virtual

Advance the stream by reading a new buffer.

Remarks

The data read by this member is accessible through getBufferImpl().

After a successful call to this member, getBufferImpl will never raise

a NoBuffer exception.

See Also

getBufferImpl

unsigned int Audio::Stream::read	(	void *	buffer,
		unsigned int	bufferSize
	)
throw	(	Exception
	)

Fill the specified buffer with data from the stream, and advance.

Remarks

If not enough data is available, but some is, instead of throwing an EndOfStream exception the function will return the amount of data actually fetched, in bytes. If no bytes at all are available, though, and EndOfStream exception will be raised.

Parameters

buffer	a pointer to a memory buffer where to extract data.
bufferSize	the size of the memory area pointed to by buffer, and the maximum amount of data to be extracted from the stream, if available.

Definition at line 40 of file Stream.cpp.

References buffer, VsnetOSS::memcpy(), and min().

    {
        void *rbuffer;
        void *rbufferEnd;
        unsigned int rbufferSize;
        unsigned int rode = 0;
        
        try {
            getBufferImpl(rbuffer, rbufferSize);
        } catch (NoBufferException) {
            nextBufferImpl();
            getBufferImpl(rbuffer, rbufferSize);
            curBufferPos = rbuffer;
        }
        rbufferEnd = ((char*)rbuffer) + rbufferSize;
        
        while (bufferSize > 0) {
            if (!((curBufferPos >= rbuffer) && (curBufferPos < rbufferEnd))) {
                nextBufferImpl();
                getBufferImpl(rbuffer, rbufferSize);
                curBufferPos = rbuffer;
                rbufferEnd = ((char*)rbuffer) + rbufferSize;
            }
            
            size_t remaining = min( bufferSize, (unsigned int)((char*)rbufferEnd - (char*)curBufferPos) ); //is there no std::ptrdiff?
            memcpy(buffer, curBufferPos, remaining);
            buffer = (void*)((char*)buffer + remaining);
            curBufferPos = (void*)((char*)curBufferPos + remaining);
            bufferSize -= remaining;
            rode += remaining;
        }
        
        return rode;
    }

void Audio::Stream::seek	(	double	position)
throw	(	Exception
	)

Set the stream's position, in seconds

Remarks

The final position in the stream after this operation is not guaranteed to be as requested, but an approximation given codec limitations. The only exception being seek(0), which is guaranteed to seek to the beginning of the stream.

Definition at line 35 of file Stream.cpp.

    {
        seekImpl(position);
    }

virtual void Audio::Stream::seekImpl ( double  position) throw ( Exception )

protectedpure virtual

See Also

seek

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

• src/audio/Stream.h
• src/audio/Stream.cpp