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roar_vs_latency(3) [debian man page]

roar_vs_position(3)					   RoarAudio Programmer's Manual				       roar_vs_position(3)

NAME

       roar_vs_position, roar_vs_latency, roar_vs_latency2 - Get stream position information

SYNOPSIS

       #include <roaraudio.h>

       ssize_t roar_vs_position(roar_vs_t * vss, int backend, int * error);

       roar_mus_t roar_vs_latency(roar_vs_t * vss, int backend, int * error);

       roar_mus_t roar_vs_latency2(roar_vs_t * vss, int backend, int wait, int * error);

DESCRIPTION

       roar_vs_position() returns the current server site position of the stream plus the current offset for the selected backend.

       roar_vs_latency() returns the latency between the client site stream position and the server site position plus the latency by the backend.

       Use of roar_vs_latency() is not recommended as it requires the codec to use a true constant bit rate.

       roar_vs_latency2()  is perfectly equivalent to roar_vs_latency() expect that it takes the additional parameter wait. The wait parameter may
       have the values ROAR_VS_WAIT, ROAR_VS_NOWAIT and ROAR_VS_ASYNC.	If it is ROAR_VS_WAIT the function does the same as roar_vs_latency().	If
       the parameter is ROAR_VS_NOWAIT roar_vs_latency2() will return interpolated data based on old data collected by calls to roar_vs_latency(),
       roar_vs_latency2() or roar_vs_position().  ROAR_VS_ASYNC is used to trigger asyncron updates to this internal  state.  Asyncron	operations
       need to be enabled before they can be used. See roar_vs_ctl(3).

       Calling	these  functions  too  often  will result in bad performance and incorrect data (pool interval smaller than server response time).
       Polling up to 20 times per second shoudn't be a problem.

PARAMETERS

       vss    The VS object to be used.

       backend
	      The backend used for correction. This can be a stream ID of the stream to use as backend or one of the special values defined by the
	      constants ROAR_VS_BACKEND_*.  ROAR_VS_BACKEND_NONE is used to ask for no correction.  ROAR_VS_BACKEND_DEFAULT is used to ask for the
	      default correction. This should be used in all common cases.  ROAR_VS_BACKEND_FIRST is used to ask for correction based on the first
	      primary stream on the same mixer.

       wait   Tells the API if the call should wait or not. Must be ROAR_VS_WAIT, ROAR_VS_NOWAIT or ROAR_VS_ASYNC.

       error  This  is	a pointer to a integer used to store the error value in case of error.	This can be NULL if not used but it is very recom-
	      mended to use this error value to report good error messages to the user.

RETURN VALUE

       roar_vs_position() returns the stream position on success and -1 on error.  Stream position is the current position of the stream in  units
       of samples (not frames!).

       roar_vs_latency()  returns the stream latency on success and zero on error. However zero is a valid value. In case of error error is set to
       the error. In case of no error but zero latency error is cleared (set to ROAR_ERROR_NONE).  Latency is retruned in mu-seconds (1/10^-6s).

EXAMPLES

       FIXME

SEE ALSO

       roarvs(7), libroar(7), RoarAudio(7).

RoarAudio							     June 2011						       roar_vs_position(3)

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roar_vs_stream(3)					   RoarAudio Programmer's Manual					 roar_vs_stream(3)

NAME

       roar_vs_stream - Set up stream parameters for VS object

SYNOPSIS

       #include <roaraudio.h>

       int roar_vs_stream(roar_vs_t * vss, const struct roar_audio_info * info, int dir, int * error);

DESCRIPTION

       This  function  asks a VS object opened by roar_vs_new_from_con(3) or roar_vs_new(3) to open the data connection using the audio parameters
       info and the stream direction dir.

       This function needs to be called before data is read or written if one of the above functions is used to create the VS object.

       This function is also used to provide parameters for the file mode (which is started by using roar_vs_file(3)  or  roar_vs_file_simple(3)).
       To  play  back  a  file	this  is not needed in a common case as the VS API tries to find correct parameters.  It is required for all other
       stream directions. See roar_vs_file(3) and roar_vs_file_simple(3) for more information.

       On failture this function can be called again with diffrent parameters.

PARAMETERS

       vss    The VS object to be updated.

       info   This is a pointer to the roar_audio_info structure storing the audio format parameters.  The structure contains the following  meme-
	      bers: rate (sample rate), bits (bits per sample), channels (channels per frame) and codec.

       dir    This  is	the stream direction. Common values include ROAR_DIR_PLAY for waveform playback, ROAR_DIR_MONITOR for waveform monitoring,
	      ROAR_DIR_RECORD for waveform recording.  For MIDI ROAR_DIR_MIDI_IN and ROAR_DIR_MIDI_OUT is used.

       error  This is a pointer to a integer used to store the error value in case of error.  This can be NULL if not used but it is  very  recom-
	      mended to use this error value to report good error messages to the user.

RETURN VALUE

       On success these calls return 0.  On error, -1 is returned.

EXAMPLES

	struct roar_audio_info info;
	int err;

	if ( roar_profile2info(&info, "isdn-eu") == -1 ) {
	 // error handling.
	}

	if ( roar_vs_stream(vss, &info, ROAR_DIR_PLAY, &err) == -1 ) {
	 // error handling.
	}

SEE ALSO

       roar_vs_file(3), roar_vs_file_simple(3), roarvs(7), libroar(7), RoarAudio(7).

RoarAudio							     June 2011							 roar_vs_stream(3)
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