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avcapture(1)							  avcapture(1)

NAME    [Toc]    [Back]

     avcapture - capture and synchronization tool for uncompressed video and

SYNOPSIS    [Toc]    [Back]

     avcapture [ -a # ]	[ -b # ] [ -c #	] [ -d # ] [ -f	%s ]
	       [ -h ] [	-i # ] [ -o # ]	[ -p # ] [ -t %s ]
	       [ -v vlan_cmd_file ] [ -w # ] [ -A ] [ -B ]
	       [ -D ] [	-F ] [ -R ] [ -T ] [ -V	] [ filename ]

PARAMETERS    [Toc]    [Back]

     -a	<audio format>
	  specifies the	file format of the audio data
	     1 =  no audio (default)
	     2 =  QuickTime (currently not implemented)
	     3 =  AIFC

     -b	<buffer	size>
	  allows you to	specify	the maximum number of buffer elements to be
	  allocated. By	default, 30 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.

     -c	<colorspace>
	  specifies the	image colorspace (see /usr/include/dmedia/vl.h or the
	  Digital Media	Programming Guide for definitions).  The default is
	     1 =  CCIR601 YCbCr	(default) [YUV(A) with headroom]
	     2 =  SMPTE	YUV		  [YUV(A) full range]
	     3 =  RP175			  [RGB(A) with headroom]
	     4 =  RGB			  [RGB(A) full range]

     -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.

     -f	<capture format>
	  specifies the	capture	format of the video data:
	     frames =  uncompressed frames
	     fields =  uncompressed fields

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

									Page 1

avcapture(1)							  avcapture(1)

     -i	<number	of frames>
	  specifies the	number of video	images to capture. By default 60
	  fields are transferred.

     -p	<VL packing type>
	  specifies the	pixel packing; see /usr/include/dmedia/vl.h for
	  definitions.	The default is VL_PACKING_R422_8; (This	is the most
	  efficient selection, since it	only takes 16 bits per pixel; all 444
	  packing selections take 24 bits per pixel; all 4444 packing
	  selections take 32 bits per pixel).
	     1 =  R242_8 (default)
	     2 =  242_8
	     3 =  444_8
	     4 =  R444_8
	     5 =  4444_8
	     6 =  R4444_8

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

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

     -w	<scatter gather>
	  specifies the	number of images to simultaneously write to disk using

     -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 data is captured to	disk.

     -D	  enables loquacious output for	debugging purposes.

     -F	  swap field dominance (works only in fields mode).

     -R	  enables Rice encoding	(DIVO only).

									Page 2

avcapture(1)							  avcapture(1)

     -T	  trigger with VITC.

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

	  specifies the	name of	the file to store the video data.  If the -a3
	  option is chosen audio data will be stored in	a separate audio file,
	  filename.aifc.  If the files already exist they will be truncated.

DESCRIPTION    [Toc]    [Back]

     The utility avcapture uses	the Digital Media libraries to record a
     sequence of video images input from a Silicon Graphics video device.
     Audio data	can also be captured in	a separate AIFC	file with the -a
     option.  If the audio and video hardware are locked to a common external
     reference signal the audio	and video data are guaranteed to be

     avcapture is best suited to store 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.  The
     logical volume, xlv_mgr and xlv_assemble, and file	system,	mkfs_xfs,
     administration tools to configure your disk array.	 Another set of
     production	utilities, diskalign and diskperf are also available and make
     an	otherwise daunting task	much simpler to	perform.

     Files created with	this utility will be written in	the QuickTime file
     format.  See /usr/share/src/dmedia/movie for details on how to create and
     edit QuickTime files using	the SGI	movie library.

     The size of a video image is determined by	the combination	of the capture
     mode, fields or frames, colorspace, and packing.  The image size and
     video format are then used	to compute the required	data transfer rate.
     The video input timing and	format must be set beforehand with vcp.	 If
     audio input is selected with the -a option	the default audio device is
     used.  The	audio control parameters can be	adjusted with apanel.

     avcapture can be run in two ways, burst mode or stream mode.  In stream
     mode it is	assumed	that the disk array onto which the data	will be
     recorded has been performance tested for the specified data format.  The
     video data	is recorded directly to	a file through a small fifo in memory
     as	defined	by the -b buffer size option.  If the disk device is not setup
     for real-time capture the -b option can be	used to	record in batch	mode
     fashion using as many buffers as can be stored in memory with frame
     accurate control in small intervals over the desired duration of time.

     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

									Page 3

avcapture(1)							  avcapture(1)

     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
     input of the video	device must be connected to the	V-LAN transmitter 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 input.	 See Appendix A	of the DIVO XIO	Board Owner's Guide
     for details.

SEE ALSO    [Toc]    [Back]

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

NOTES    [Toc]    [Back]

     avcapture runs in "compatibility mode" when using the Octane Digital
     Video board with Irix 6.4.	 This is due to	the evolution of the VL	API.
     The DIVO board supports the new API on Irix 6.4, but Octane Digital Video
     will not support the new API until	Irix 6.5.  Consequently, there is a
     requirement to map	the colorspace and packing specified in	the new	API
     model back	to the format and packing model	of the old API;	unfortunately,
     not all combinations are supported.  Refer	to the avcapture source	in

									PPPPaaaaggggeeee 4444
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