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avplayback(1)							 avplayback(1)

NAME    [Toc]    [Back]

     avplayback	- playback uncompressed	video and audio	in synchronization

SYNOPSIS    [Toc]    [Back]

     avplayback	-[a# b#	d# h r#	t%s v vlan_cmd_file A B	D V] <filename>

PARAMETERS    [Toc]    [Back]

     -a	<audio format>
	  specifies the	file format of the audio data:
	     1 =  no audio
	     2 =  QuickTime
	     3 =  AIFC
	  If audio output is not disabled with -a1 an embedded audio track
	  will be played if it exists.	If an embedded track does not exist
	  then a file with the suffix .aifc will be opened for playback.

     -b	<buffer	size>
	  allows you to	specify	the maximum number of buffer elements to be
	  allocated. By	default, 4 buffers are used, but the value can be
	  adjusted for I/O load	balancing. The maximum number of buffers which
	  can be allocated is limited by the amount of available physical
	  memory in the	system.

     -d	<video device number>
	  specifies the	video device to	be used	(as reported by	vlinfo).  This
	  need not be specified	unless you have	more than one video device in
	  your system; it defaults to 0, i.e. the first	device found.

     -h	  prints a usage message giving	a summary of available flags.

     -r	<scatter gather>
	  specifies the	number of images to simultaneously read	from disk
	  using	readv(2)

     -t	</dev/ttyd#>
	  specify the tty device port for serial RS422 V-LAN control

     -v	  instructs the	program	to parse the specified file for	V-LAN commands
	  and to issue them immediately.

     -A	  abort	if any image is	dropped	(when a	VL sequence lost event is

     -B	  calculates the video disk I/O	performance and	prints the results
	  after	the last image is output.

									Page 1

avplayback(1)							 avplayback(1)

     -V	  enables verbose mode and prints the values of	parameters used	to
	  setup	the hardware for audio and video transfers.

     <filename>	  specifies the	name of	the file to read.  If the -a2 option
		  is chosen audio data will be in the separate file
		  filename.aifc.  If the -a3 option is chosen audio data will
		  be embedded in the QuickTime file filename.

DESCRIPTION    [Toc]    [Back]

     The utility avplayback uses the Digital Media libraries to	output a
     sequence of video images and audio	samples	from various Silicon Graphics
     digital media devices.  As	of this	release	audio data originally captured
     with avcapture in a separate AIFC file played in sync with	the video
     using the -a3 option.  If the audio and video hardware are	locked to a
     common external reference signal the audio	and video data are guaranteed
     to	remain synchronized.  If either	device drops data synchronization will
     be	recalibrated.  Visual or audio artifacts may be	noticed	at this	time.

     avplayback	is best	suited to playback large volumes of audio and video
     data in realtime.	This is	possible if a striped logical volume disk
     array of sufficient size and configuration	is used	with the XFS file
     system.  Before copying data to disk from an external source test the
     performance of the	array using the	tool diskperf.	It may be necessary to
     reconfigure the array with	diskalign before realtime playback can be

     See /usr/share/src/dmedia/movie for details on how	to create and edit
     QuickTime files using the SGI movie library.

     All of the	video control parameters including output timing and data
     format are	automatically set by the tool.	If audio output	is enabled
     default audio device is used.  The	audio control parameters can be
     adjusted with apanel.

     The -v option specifies a text file containing V-LAN edit commands.
     Robust error checking is not performed, therefore,	unpredictable behavior
     should be expected	if invalid V-LAN commands are issued or	if the
     commands are issued in the	wrong order.  Permissions and ownership	of the
     command file must be properly set.	 If V-LAN control is chosen and	the CO
     (Coincidence On) and SC (Set Coincidence) commands	are issued the GPI
     output of the video device	must be	connected to the V-LAN receiver	in
     order to accurately initiate the data transfer.  This option should be
     used in conjunction with the -t flag.  A special cable must be
     constructed for the trigger output.  See Appendix A of the	DIVO XIO Board
     Owner's Guide for details.

SEE ALSO    [Toc]    [Back]

     avcapture(1), diskalign(1), diskperf(1), memtovid(1), orion(1),

									PPPPaaaaggggeeee 2222
[ Back ]
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