O2Video(7)
O2Video - O2 Video System
Showing IRIX 6.5.30 (default release). Unchanged since IRIX 6.5.
NAME O2Video - O2 Video System DESCRIPTION O2Video (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. 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. 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 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). 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). 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. 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) 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) 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). 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 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. 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 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 ALSO mvp(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.