The UMSVideoInLM object provides support for GT20 Graphics Adapter video capture hardware. This object inherits or overrides all methods from the UMSVideoIn base class and does not add new methods.
This object supports the YUV422 and YUV422_UYVY image formats.
A YUV422 image is composed of 32 bits per pair of pixels. The pixels are in order from left to right, top to bottom. For each pair of pixels in memory, the first 8 bits are Y1. The next 8 bits are U. The next 8 bits are Y2. The last 8 bits are V.
A YUV422_UYVY image is composed of 32 bits per pair of pixels. The pixels are in order from left to right, top to bottom. For each pair of pixels in memory, the first 8 bits are U. The next 8 bits are Y1. The next 8 bits are V. The last 8 bits are Y2.
Because of the format of the YUV422 and YUV422_UYVY images, the width must be an even number.
When the Movie Editor program is used to capture video, the image rate is about five per second for NTSC at 320x240 pixels. The performance does change with image size and system load.
The maximum capture size is 320x240 pixels for NTSC and 384x288 for PAL.
The supported inputs for the set_input_connector method are LINE_IN and INTERNAL_CAMERA. The strings "INPUT_COMPOSITE", "INPUT_COMPOSITE_1", and "INPUT_COMPOSITE_2" are treated the same as LINE_IN. The string "INPUT_CCDCAMERA" is treated the same as INTERNAL_CAMERA.
There are no supported output connectors for the set_output_connector method.
The supported signal formats for the set_signal_format method are NTSC and PAL. The internal camera produces NTSC.
You can set three defaults in the UMS_config file for this object. The stanza begins with the text "UMSVideoInLM:". The setting for default_input_connector can be set to the same values that the set_input_connector method accepts. The setting for default_signal_format can be set to NTSC or PAL. The setting for default_color_key can be set to the name of any color that the X11 function XAllocNamedColor accepts.
The UMSVideoInLM object uses color keying to clip the video to the window boundary. The method is similar to, but not the same as, chroma-keying. The color used for keying is specified in the UMS_config file in the default_color_key setting. There is no way to prevent other applications from using the same color. The video might show through into other windows. The user can change the color in the configuration file to reduce the interference.
The UMSVideoInLM and UMSImageWindowLM objects talk to the same hardware. There can be only one of these objects active at a time.
For introductory information, see Programming with Video and Monitor Support Objects.