rtf_filter(3) [debian man page]

RTF_FILTER(3)							 rtfilter library						     RTF_FILTER(3)

NAME

       rtf_filter - filters a chunk of data

SYNOPSIS

       #include <rtfilter.h>

       unsigned int rtf_filter(hfilter filt, const void *x,
			       void *y, unsigned int ns);

DESCRIPTION

       This  function  applies	the filter referenced by filt on ns samples specified by the pointer x and writes the filtered data into the array
       pointed by y. The arrays pointed by made of values whose correspond to the type specified at the creation of the filter. In  addition,  the
       two arrays must not overlap (failing to comply will lead to undefined results).

       Their  number  of elements have to be equal to ns multiplied by the number of channels processed (specified at the creation of the filter).
       The arrays should be packed by channels with the following pattern:
						   |S1C1|S1C2|...|S1Ck|S2C1|S2C2|....|S2Ck|...|SnsCk|
       where SiCj refers to the data value of the i-th sample and the j-th channel and k refers to the number of channel specified at the creation
       of the filter.

RETURN VALUE

       Returns	the  number  of samples written in the array pointer by y. For most of the filters, this value will always be equal to ns. This is
       however not the case of a downsampling filter whose the number of samples returned may vary from one call to another.

PERFORMANCE CONSIDERATION

       On platforms that support SIMD instructions, rtf_filter() is implemented in 2 different versions: one normal and one using SIMD instruction
       set  which  performs  nearly  4x faster than the normal one when processing float data types. The SIMD version is automatically selected at
       runtime if the following conditions are met (otherwise, the implementation falls back to the normal version):

	- The input x and output y are aligned on 16 bytes boundary (128 bits)

	- The sample strides (the size of the data type multiplied by the number of channel) of the input and output are multiples of 16 bytes.

       The first condition is easily met by allocating x and y using memory allocation	function  mandating  a	certain  alignment  (for  example,
       posix_memalign(3) on POSIX platform).

       The  second  condition  is  met if the number of channels is carefully chosen.  Given the boost obtained with the SIMD version, it is often
       interesting to add unused channels into the input and output (when possible) just to make the strides multiple of  16  bytes  (for  example
       using always a multiple of 4 channels when dealing with float and real values).

SEE ALSO

       rtf_create_filter(3), rtf_init_filter(3)

EPFL
								       2010							     RTF_FILTER(3)

Check Out this Related Man Page

SDL_AudioSpec(3)						 SDL API Reference						  SDL_AudioSpec(3)

NAME

       SDL_AudioSpec - Audio Specification Structure

STRUCTURE DEFINITION

       typedef struct{
	 int freq;
	 Uint16 format;
	 Uint8 channels;
	 Uint8 silence;
	 Uint16 samples;
	 Uint32 size;
	 void (*callback)(void *userdata, Uint8 *stream, int len);
	 void *userdata;
       } SDL_AudioSpec;

STRUCTURE DATA

       freq		   Audio frequency in samples per second

       format		   Audio data format

       channels 	   Number of channels: 1 mono, 2 stereo

       silence		   Audio buffer silence value (calculated)

       samples		   Audio buffer size in samples

       size		   Audio buffer size in bytes (calculated)

       callback(..)	   Callback function for filling the audio buffer

       userdata 	   Pointer the user data which is passed to the callback function

DESCRIPTION

       The  SDL_AudioSpec  structure  is  used to describe the format of some audio data. This structure is used by SDL_OpenAudio and SDL_LoadWAV.
       While all fields are used by SDL_OpenAudio only freq, format, samples and channels are used by SDL_LoadWAV. We  will  detail  these  common
       members here.

       freq		   The	number	of samples sent to the sound device every second. Common values are 11025, 22050 and 44100. The higher the
			   better.

       format		   Specifies the size and type of each sample element

       AUDIO_U8

       AUDIO_S8

       AUDIO_U16 or AUDIO_U16LSB

       AUDIO_S16 or AUDIO_S16LSB

       AUDIO_U16MSB

       AUDIO_S16MSB

       AUDIO_U16SYS

       AUDIO_S16SYS

       channels 	   The number of seperate sound channels. 1 is mono (single channel), 2 is stereo (dual channel).

       samples		   When used with SDL_OpenAudio this refers to the size of the audio buffer in samples. A sample a chunk of audio data	of
			   the size specified in format mulitplied by the number of channels. When the SDL_AudioSpec is used with SDL_LoadWAV sam-
			   ples is set to 4096.

SEE ALSO

       SDL_OpenAudio, SDL_LoadWAV

SDL
							      Tue 11 Sep 2001, 22:58						  SDL_AudioSpec(3)

Linux and UNIX Man Pages

rtf_filter(3) [debian man page]

Check Out this Related Man Page