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O2Video(7)O2Video(7)NAMEO2Video - O2 Video System
DESCRIPTIONO2Video (aka "mvp") is the built in multiport video processor on the O2
System. There are two types of Audio/Video interface cards available.
The first is termed the "Analog A/V" interface and is identified in the
"hinv" output as "AV1". The second type is termed the "Digital A/V"
interface and it's name is "AV2" when examining the "hinv" output.
The AV1 interface supports Composite and SVideo (Y/C) (both analog), and
Digital I/O via the Camera/Digital Video port. The analog I/O jacks are
for use with standard analog video equipment, supporting both PAL and
NTSC video formats. There are a variety of controls available that allow
the user or programmer to set various parameters used for the decoding
and encoding of the video signals.
The digital input is for use with the O2 Digital System Camera, or can be
connected to an optional digital video input and output adapter to
interface to standard SMPTE259M serial digital video devices (contact SGI
Sales for digital video "dongle" information).
The AV2 interface supports two ITU-601 (CCIR-601) serial digital video
input connectors and two similiar output connectors, as well as GPI input
and output and analog (black burst) sync input and loop through.
O2Video simultaneously supports two input video streams to memory and one
output video stream from memory which can be seperated into two outputs,
one carrying pixel information, the other carrying alpha (key)
information.
Using O2Video, it is possible to capture live video into the computer's
memory which can then be displayed in a graphics window on the screen or
further processed by an application. It is also possible to generate
video output from images in memory, which can be displayed on a standard
video monitor, or recorded to a VTR. Using the VL programming library
(see vlintro(3), and mvp(3)), a program can capture video in either the
RGB or YCrCb color spaces, and either full or reduced size formats, and
in a format usable for input to the compressor/decompressor, display on
the graphics screen, or as an input to a graphics processing and/or
texture operation.
There is also a screen capture feature for the direct capture of images
from the graphics screen into memory.
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O2Video(7)O2Video(7)
O2 Media Applications
A full suite of media applications are packaged with the O2 system to
take advantage of the resident hardware. See mediarecorder(1),
moviemaker(1), and movieplayer(1). In addition, there are some
programming examples supplied with source under /usr/share/src/dmedia,
that highlight some of the features of the O2 Audio, Video, Compression
and Graphics systems.
O2Video Control Panel
The video control program, videopanel(1) allows the user to control the
inputs, the output, and their timing. Additionally, it allows the user to
set certain device parameters which are described below. The factory
defaults for all of these controls are stored in the file
/usr/lib/dmedia/video/defaults/mvp, which is the file restored when the
"File>Restore Factory Settings" is selected from the videopanel File
menu. When "File>Save Settings" is selected from the videopanel File
menu, the current settings are saved to the file $HOME/.videopanelrc.
These settings may be restored by selecting "File>Restore Settings."
The videopanels are different depending on whether there is an AV1 or an
AV2 interface card installed (there is also an "audio only" system which
still contains some video channel features though there are no external
connectors. See mvp(3) for more details.
The Main Level video control panel contains the following controls:
Default Input
This selects the default input source for applications. The choices
correspond to the connectors on the machine. In addition, it can
have an effect on the genlock source (see ""Genlock Source"
description below).
The possible selections for default input are "composite", "svideo",
"digital", "camera", "primary" or "secondary digital video", and
"output video".
The Composite input is an RCA-type two wire connector that is
commonly found on VCRs and cameras. The SVideo input uses a mini-
DIN connector that has separate signals for luminance and
chrominance (sometimes referred to as Y/C). Better VCRs and cameras
support SVideo which generally results in a superior picture.
The Camera input selects the O2 Digital System Camera provided with
the system.
The Digital input selects the optional serial digital adapter
(dongle) device, if connected.
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O2Video(7)O2Video(7)
Primary and Secondary Digital Video refer to the top and 2nd from
top connectors on the AV2 card.
The Output input selects a loopback connection internal to the video
subsystem. Anything that is being output to the video output DMA
channel will be sent back in via the video input DMA channel. All
digital output processing is performed as well as input processing.
The loopback is routed before encountering any analog circuitry. To
loopback the analog signal, an external cable must be used.
Input Timing
Each of the video input ports has a menu to select its default
timing. The O2 Video System is a 4:3 (Non-square) aspect ratio.
The "Square" timings enable a non-square to square filter to capture
the incoming 4:3 aspect pixels and convert them to a 1:1 aspect
ratio suitable for processing and/or displaying with a 1:1 aspect
ratio graphics system. Note that this processing (or more correctly
"interpolation") adversely affects high frequency video response.
Output Timing
The output port has a menu to select its default timing. The Square
timings enable a square to non-square filter to send outgoing pixels
that are of a 1:1 aspect ratio to the correct NTSC or PAL aspect
ratio of 4:3.
White Balance
The white balance button causes the camera to automatically
configure the red and blue balances to achieve an overall even toned
image. For best results, hold up a well lit piece of white paper in
front of the camera and click on white balance, the camera will then
calibrate itself.
Selecting the ``Pro'' menus from the Main Level video control panel
brings up control panels which control various parts of the O2Video
system.
Device Controls
These controls are used to specify the video clock source which can be
used to drive the O2 system graphics and audio devices.
Graphics Genlock (Framelock)
This controls the genlock signal sent to the graphics subsystem. The
genlock source can be Video output, SVideo/Composite (analog input),
Digital Video (digital input), Primary or Secondary Digital Video or
an external genlock input (available on the AV2 Serial Digital Video
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O2Video(7)O2Video(7)
Interface only).
Note that the systune variable mvpframelock_enable must be set to 1
for this control to take effect. See systune(1M) for more details.
Audio Genlock
This controls the genlock signal sent to the audio subsystem. The
genlock source can be None, SVideo/Composite (analog input), Digital
Video (digital input), Primary or Secondary Digital Video, or an
external genlock input (available on the AV2 Serial Digital Video
Interface only).
SVideo and Composite Controls
The analog video input controls are used to configure the two standard
analog video input ports on O2Video. The main panel allows setting the
default input timing for each input port. The rest of the controls are
located on the SVideo and Composite control panels and are only
applicable to systems equipped with the AV1 Audio/Video interface.
Note that these panels are duplicates of each other since they are
controlling the same analog decoder, though some controls may be
applicable to only one of the input sources.
Auto Gain Control
This toggle engages an automatic gain control circuit before
digitization which maximizes dynamic range. When disabled,
luminance and chrominance can be manually adjusted by the two Gain
sliders at the bottom of this panel (AV1 only).
VTR Mode
This toggle controls the synchronization of the input video signal.
When enabled, the O2Video analog port attempts to track the input
signal continuously. When disabled, the O2Video analog port matches
the input signal but does not make continual adjustments. With
video sources that fluctuate, the VTR lock usually generates a
clearer picture (AV1 only).
Disable Chroma Comb Filter
This engages a comb filter that removes luminance information from
the bandpassed chrominance signal before demodulation (AV1 only).
Prefilter
The Prefilter engages a high frequency boost that can be used for
edge enhancement, or to compensate for a soft input image (AV1
only).
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Filter Bypass
This toggle can be used to bypass the bandpass filter used to
separate chrominance from luminance in the decoder. Ordinarily this
filter is engaged for composite video inputs and disabled for SVideo
inputs. It may useful to disengage this filter when receiving a
monochrome composite signal.
Aperture
This adjustment affects the horizontal sharpness of the picture (AV1
only).
Vy(dB) Gain Depending on Aperture Setting
fy (MHz) 0 0.25 0.5 1.0
---------------------
0 3 3 3 3
1 3 3 3 3
2 3 3 3 3.5
3 2.5 3 3.5 4
4 2 3 4 5
5 1.5 3 4.5 6
6 1 3 4 6
7 0 2 4 6
8 -1 1 2.5 5
Bandpass
This adjustment also affects the sharpness of the picture. The
bandpass filter can be programmed to different frequencies even when
the chroma trap is bypassed (AV1 only).
Chroma Bandwidth
This selects one of four low-pass filters in the decoder that
determines chrominance bandwidth (AV1 only).
Luma Delay
This controls the relative alignment of luminance to chrominance in
the digital stream produced by the decoder in 74ns increments (AV1
only).
Brightness
This controls the amplitude of the luminance signal video signal
produced by the decoder (AV1 only).
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Contrast
This controls the dynamic range of the luminace signal produced by
the video decoder (AV1 only).
Saturation
This controls the amplitude or "vividness" of the color information
produced by the decoder (AV1 only).
Hue This adjusts the balance between colors in the signal (AV1 only).
Camera Controls
These controls affect the behavior of the O2 Digital System Camera, and
are only present if there is an O2Camera plugged into the O2 Digital
Video input connector.
Note that the driver must be reloaded (see "Reload Driver" below) if the
camera is plugged in or unplugged for the change to be recognized.
Auto Gain Control
This toggle button turns on or off the automatic gain control in the
camera. When automatic gain control is on, the camera continually
adjusts itself to changing lighting conditions in order to produce
an even level of brightness. When automatic gain control is off, it
is up to the user or program to set the proper gain level. If the
gain is too low, then the picture will appear dark; when the gain is
too high it will appear white or washed out.
Camera LED
This toggle button turns on or off the LED on the Camera.
Camera Shutter
This multiple choice control lets you control the shutter speed of
the camera. A faster shutter speed lets in less light and may be
used when the amount of light is too high to be compensated for by
the gain control.
Gain This control is used when the automatic gain has been turned off.
It allows manual adjustment of the camera exposure.
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Red Balance
The red balance controls the proportion of red in the image.
Blue Balance
The blue balance controls the proportion of blue in the image.
Red Saturation
The red saturation value affects the overall red color intensity of
the image. When red saturation is set to zero, the image will have
no red color.
Blue Saturation
The blue saturation value affects the overall blue color intensity
of the image. When blue saturation is set to zero, the image will
have no blue color.
Gamma
The gamma value affects the brightness of dark areas in the image.
Increasing the gamma value increases the brighness of dark areas.
Digital Input Controls
There are no user controls defined for the Digital Video inputs.
Output Controls
These controls affect the behavior of the O2Video video ouptut as well as
the analog video output. Note that the analog video controls are only
present when an AV1 video interface card is installed.
Standard Blanking
When set off, Vertical Blanking is defined by first active line.
When set on, Vertical Blanking is forced according to CCIR-624
(50Hz) or RS-170A (60Hz). (AV1 only)
Output Sync
This selects one of two sources for output video timing, either
internal or genlock. Internal timing is locked to a crystal inside
the system that generates video timing and then applies it to the
video output. Internal timing should be used when a video stream is
to be produced by the system independent of an external reference.
Genlock should be selected when it is desired that output video
timing reflect the timing selected by the Genlock source select
menu. (AV1 or AV2)
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O2Video(7)O2Video(7)
Genlock Source
This selects the source of the genlock signal when Output Sync is
set to "genlock". When SVideo/Composite is selected, the
horizontal, vertical, and subcarrier timing appearing on the analog
inputs is applied to the analog video output, with the horizontal
and vertical timing applied to the digital video output. (AV1 or
AV2)
When Digital, Primary, Secondary, or External is selected, that
source's horizontal and vertical timing is applied to both the
analog and digital video outputs of the machine (and there is no
subcarrier timing applied to the analog video).
Obviously the timing of the genlock source device must match the
timing selected on the Video Output section of the main video panel.
Also note that the O2Camera can not be used as a genlock source as
it does not send standard timing.
When the MVP driver first loads, unless the PROM variables are set
(see "PROM" below), it will select the genlock source based on the
what the default source is. This is because the O2 Video hardware
selects the "passthru" (pass through) source via the genlock source.
Therefore, to enable the quiescent state of passing the input to the
output, the software needs to adjust the genlock source. In
addition, the output timing is set to match the default source
timing.
If the "Output Sync" or "Genlock Source" is set by the user (either
from a program or the videopanel), then the automatic "passthru"
feature is enabled only for the current timing and genlock source
(NOT the default source). This keeps the selected genlock source
from being altered, and the output timing changed.
To re-enable the automatic "passthru" (and thus "deselecting" the
genlock source), the "Default Signal" (below) must be set to "image"
[even if it's already set to "image".] After this control is set,
"Genlock Source" is once again tracking the "Default Source" (and
it's timing), whenever the video output channel is not being used by
a program.
Passthru mode can also be enabled with the "Output Enable" control.
Default Signal
This selects one of three possible default signals for the video
outputs of the system when no application is driving the video
output port. Either Black, Color Bars, or Image can be presented at
the video outputs. Image selects the signal present at the "Default
Source" input of the video system and is referred to as "Passthru"
mode. "Black" sends a valid output signal with luma and chroma set
to minimum. (AV1 or AV2)
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The Color Bars signal is a synthetic image contained in the
programmable memory of the analog video encoder and is sent only to
the analog video output connectors (composite and svideo). On the
digital video outputs, "Black" will be sent when "Color Bars" is
selected. (AV1 only)
Note, in addition, the O2 Digital Camera (version 1) can not be used
as a default source for "Passthru" mode as it's input timing is not
standard NTSC or PAL.
Output Enable
This controls which data is sent to the O2 output video ports. The
following selections are provided. Note that these only apply to
output pixel packings that include the alpha channel. (AV1 or AV2)
Analog Digital
Selection Output Output
------------------------
pixels/pixels pixels pixels
pixels/alpha pixels alpha
alpha/pixels alpha pixels
alpha/alpha alpha alpha
Luminance Range
Normally the Luminance Gain for White-Black is 92.5 IRE (including
7.5 IRE Setup of Black) for NTSC timing and 100 IRE for PAL timing.
This control allows the user to independently change this setting
irregardless of the timing (AV1 only).
First Unblanked Line Out
This controls the position of the first active line in the video
image. The position of first active line can be advanced to allow
the passage of software encoded vertical information, or can be
delayed to defeat the premature introduction of setup in blanking,
in an NTSC image. Note that "Standard Blanking" must be off for
this control to take effect and this control only affects the analog
video output (AV1 only).
Cb Gain
This controls the amplitude of the Cb color signal. This is useful
when adjusting the color produced by the system when used in
conjunction with a vectorscope (AV1 only).
Cr Gain
This controls the amplitude of the Cr color signal (AV1 only).
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Black Level
This adjusts the blacklevel offset of the analog video output of the
system. The standard setting is for 0 offset in PAL and 7.5 IRE in
NTSC (AV1 only).
Chroma Phase
This adjusts the phase of the encoded color subcarrier (including
burst) relaitve to H Sync (AV1 only).
Horizontal Genlock Delay
This adjusts the horizontal delay between the genlock source and the
video output and is only used when a genlock signal is used and not
with the internal timing generator. When this horizontal delay is
trimmed out, the AV1 board has a one line delay from input to
output, while the AV2 board, when genlocked to external sync, has no
such vertical offset. The Vertical Genlock Delay control can be
used to adjust the vertical delay component on the AV1 board. (AV1
or AV2)
Vertical Genlock Delay
This adjusts the vertical trigger phase delay between the genlock
source and the video output on the analog video of the AV1 board in
increments of half lines. (AV1 only)
PRODUCT SPECIFIC ISSUES
Automatic Active Input Detection
The O2Video software automatically probes for the active video
inputs when it is first started. The order or precedence in
selecting the default input is:
Input signal(s) active:
Digital SVideo Composite Camera Default Source
-----------------------------------------
yes x x x digital
no yes x x svideo
no no yes x composite
no no no yes camera
no no no no composite
This allows you, for example, to use the VCR's power button to
change the default input between it and the O2 Digital System Camera
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when first starting up the O2 System.
PROM Selection of Timing, Input, Output and Genlock
In addition to the active input detection, the MVP can be set up to
select the timing, input, output and genlock at system power on.
The following PROM variables are used:
variable: videotiming
function: selects default timing
values: ntsc, pal
variable: videoinput (*)
function: selects default input
values: composite, svideo, camera, digital,
primary, secondary
variable: videooutput
function: selects default output
values: black, image, colorbars
variable: videogenlock (*)
function: selects output genlock
values: analog, digital, internal, external,
primary, secondary
variable: videostatus
function: returns PROM video status
values:
inited: video system initialized.
illegal_env_var: one or more of the
above variables were not set correctly.
av_error: an error occured accessing
the A/V interface.
The variables are set with the PROM "setenv -p" command:
setenv -p variable value
(*) Note that the videoinput and videogenlock args should correspond
with the type of A/V card installed. In other words, options
"composite, svideo, camera and digital" are appropriate for the AV1
card. Options "primary, secondary, and external" are appropriate
for the AV2 card.
The driver will initialize the AV2 interface card, even though the
PROM does not yet support this interface. This means that the AV2
video interface is not initialized at system power on but when the
the driver is loaded. An update to the PROM will be available soon
after IRIX Release 6.5 is available.
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Input Signal Quality
Input timing and source may be changed while any video application
is running but also might cause loss of sync and undesired effects.
This also applies to restoring the factory settings.
Some VCR's don't produce stable NTSC or PAL signals when some tape
transport functions are employed. For example, switching from PLAY
to FAST FOWARD often results in a disruption of the video sync and
may cause O2Video to become confused. The system software attempts
to restart the video capture but it may not be able to and will then
return an error to the application.
Selecting Default Input Source
The default Input Source control has no effect until a video path is
created. It is used as a suggestion for applications such as videoin
to specify the desired input source.
Reloading the Video Driver
At times it's desirable to reinitialize the video system without
having to reboot, for example if the camera is plugged in while the
system is up. To accomplish this, the following steps can be taken:
$ su
# ml list
Find the "Character device driver" with the prefix "mvp". If this
is not found, then the driver is either not present on the system,
or it has been made resident with the lboot options specified in
/var/sysgen/master.d/mvp. Otherwise, the "Id:" number is used in
the following command:
# killall <video applications>
# ml unld <id>
If a message states that the device is busy, then there are still
video applications active on the system. Using the ps(1) command
("ps -ef") may aid in locating what video processes are still
active.
After the driver is unloaded, then the next video command will
reload (and reinitialize) the O2 Video System.
CAVEATS
The vlGetFrontierMSC(3dm) manpage has the following statement under the
CAVEATS section:
For some VL devices, there is a short initial period (up to ten
field times) in the lifetime of a transfer during which no frontier
MSC is available. This period begins when the application calls
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O2Video(7)O2Video(7)vlBeginTransfer(3dm) and ends when the device clocks in or out its
first media stream sample from the application's VLBuffer. An
attempt to call vlGetFrontierMSC(3dm) during this period will block
the application until the end of the period, when a valid frontier
MSC is available.
Previous to patch2836 (Irix 6.3) and the Irix6.5 version of the MVP
driver, an attempt to access an "early" Frontier MSC would return an
unreliable MSC until the video device had actually transferred at least 2
fields or a frame. In patch2836 and Irix 6.5, the driver will now
correctly wait until the Frontier MSC is "valid". To enable this new
behaviour, you must set the systune variable mvpearly_frontiermsc to a
"0". [See systune(1M) for more details.] After this is done, some
applications may seem to hang, or act strangely if they are not
programmed correctly.
FILES
/usr/lib/dmedia/video/mvp.so /usr/lib/dmedia/video/defaults/mvp
SEE ALSOmvp(3dm), vlintro(3dm), vlinfo(1), videopanel(1), videoin(1),
videoout(1), vidtomem(1), memtovid(1), mediarecorder(1), moviemaker(1),
movieplayer(1), and the Phillips 7111 and 7185 Analog Decoder and Encoder
reference sheets.
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