SndThread

Description

The SndThread class implements a processing pthread-based thread for SndObj and SndIO -derived objects. The class implements three lists of objects which are used by the processing thread to generate audio signals. Two of these lists hold pointers to SndIO-derived objects (the SNDIO_IN, for input objects and the SNDIO_OUT, for output objects). The third list holds pointers to SndObj-derived objects. Methods for adding, inserting and deleting objects to these lists are provided. Processing can be turned on or off by the ProcOn() and ProcOff() methods, respectively.

Construction

SndThread()

Public Methods

int AddObj(SndObj *obj)
int AddObj(SndIO *obj, int iolist)

int Insert(SndObj *obj, SndObj* prev)

int DeleteObj(SndObj *obj)
int DeleteObj(SndIO *obj, int iolist)

int GetStatus()
int GetSndObjNo()
int GetInputNo()
int GetOutputNo()

int ProcOn()
int ProcOff()

Code Examples

A simple example

SndThread()

Constructs an empty SndThread object.

int AddObj(SndObj *obj)

Adds a pointer to a SndObj-derived object to the top of the processing list. Returns 1 if successful and 0 if not.

int Insert(SndObj *obj, SndObj* prev)

Inserts a pointer to a SndObj-derived object to a position in the list after the SndObj object pointed by prev, which will have been previously added to the list.
This is useful to insert objects in the processing list, so that the right order of processing is obtained. For instance, if obj1 receives input from obj2, then it should be placed in the listafter obj2. The following call will make sure that this is the case

sndthread.Insert(&obj1, &obj2);

provided, of course, that obj2 has already been added to the thread list. This method returns the position of the inserted object in the list, if the insertion was succesful, 0 otherwise.

int AddObj(SndIO *obj, int iolist)

Adds a pointer to a SndIO-derived object to the specified IO list (SNDIO_IN or SNDIO_OUT). For example

sndthread.AddObj(&input, SNDIO_IN);

adds a pointer to a SndIO-derived object input to the SNDIO_IN list.

int DeleteObj(SndObj *obj)
int DeleteObj(SndIO *obj, int iolist)

Delete objects from the respective lists. As in AddOBJ(...), the parameter iolist can be either SNDIO_IN or SNDIO_OUT, the input and the output lists, respectively.

int GetStatus()
int GetSndObjNo()
int GetInputNo()
int GetOutputNo()

Various methods to get properties of a SndThread object.

GetStatus() returns the processing status (ON or OFF).
GetSndObjNo(), GetInputNo() and GetOutputNo() return the number of objects (actually pointers to objects) held in the processing, input and ouput lists, respectively

int ProcOn()
int ProcOff()

These methods are use to switch the processing thread on or off. They return the current processing status (ON or OFF). The ProcOn() will return an OFF status if it fails to start the processing thread.

A simple example

A simple example and an application template are provided in this distribution of the SndObj Library. They show the use of SndThread on the Windows (under cygwin and g++) platform. SndThread is only implemented on POSIX pthread compliant platforms (cygwin, Linux, Irix and other Unix ports of the SndObj library). It is not available on the Windows/MS Visual C++ version of the library. Compilation instructions are found here.