The Indigo2 IMPACT Compression motion JPEG option card from Silicon Graphics provides two independent channels for compression and decompression for the Indigo2 IMPACT family of desktop workstations. Besides compressing and decompressing still images, Indigo2 IMPACT Compression enables an Indigo2 IMPACT workstation to input and output compressed video and record it to disk or videotape. When Indigo2 IMPACT Video is also installed in the workstation, you can input and output CCIR 601 digital video.
Designed to work with the Indigo2 IMPACT Video, Indigo2 IMPACT Compression overcomes the obstacle presented by the colossal data streams that video sources generate. Thus, Indigo2 IMPACT Compression is a powerful tool for video production, digital video distribution, motion video analysis, and video-based training. Indigo2 IMPACT Compression is an integral part of the digital studio that combines leading computer graphics, image processing, digital video, and high-quality video in an efficient desktop environment.
 | Note: The Indigo2 IMPACT Compression option does not perform audio compression. |
For applications that demand broadcast quality, Indigo2 IMPACT Compression with Indigo2 IMPACT Video allows compressed digital video streams to be used as elements in sophisticated effects such as real-time keying, blending, and video texture mapping. The option provides an ideal environment for broadcast-quality nonlinear editing, spot playback, and still storage.
Indigo2 IMPACT Compression is an integral part of the Silicon Studio solution for film and video production, which integrates 2D and 3D graphics, image processing, digital audio, and high-quality video in a single environment.
Indigo2 IMPACT Compression features include
the ability to encode or decode the board's two channels in any combination
capture and playback of full-resolution full-motion video to and from memory or disk in real time:
60 fields or 30 frames per second compression and decompression of full-resolution NTSC video
50 fields or 25 frames per second compression and decompression of full-resolution PAL video
single-frame compression and decompression
composite or S-Video capture, and playback with genlock capability
compression ratios as low as 2:1
during real-time compression, scaling of full-size fields by half in the horizontal or vertical direction or both
real-time color-space conversion in memory-to-memory decompression or uncompressed video capture or playback modes
during decompressing to main memory or uncompressed video capture, image scaling for flexible viewing of video clips and for processing transitions and effects
compatibility with all Indigo2 IMPACT graphics solutions
data formats: 8-bit per component 4:2:2 YUV, XBGR, or RGBX (32 bits per pixel, 8 bits per component)
capture of uncompressed data to memory; playback of uncompressed data from memory
Indigo2 IMPACT Compression has these modes of operation:
capture of uncompressed video from the base analog input or optional Indigo2 IMPACT Video option into a memory buffer
playback of uncompressed video from a memory buffer to the base analog output or optional Indigo2 IMPACT Video option
compressing video from the base analog input or optional Indigo2 IMPACT Video option into a memory buffer
decompressing video from a buffer to the base analog output or optional Indigo2 IMPACT Video option
compressing an image stored in memory into another area of memory
decompressing a stored compressed image into another area of memory
Because of the high data rates produced by video sources, your priorities might alternate between image quality on the one hand and storage size and transmission bandwidth on the other. Indigo2 IMPACT Compression adjusts to your needs with a wide range of compression ratios under complete software control.
Indigo2 IMPACT Compression works with the Compression Library, a complete API for compressing single images, video-streaming applications, and more.
In this chapter:
“Using Indigo2 IMPACT Compression and Video Options” summarizes how the compression board and the Indigo2 IMPACT Video option interact.
“Using the Indigo2 IMPACT Compression Option With the Compression Library” introduces the CL.
“Using the Indigo2 IMPACT Compression Option With the Video Library” introduces the VL.
The Indigo2 IMPACT Compression option can be used as a simple analog capture and playback device for video, or with the Indigo2 IMPACT Video option for capture and playback and for CCIR 601 digital video.
The Indigo2 IMPACT Compression option's real-time compression and decompression enables you to perform nonlinear editing and real-time playback from disk of special effects, composites, and animations. The Indigo2 IMPACT Compression option uses JPEG, the ideal compression algorithm for these postproduction processes because it preserves individual video frames.
The Silicon Graphics Compression Library (CL) was designed to exploit the full capabilities of the Indigo2 IMPACT Compression option:
compression ratios
data formats
in conjunction with the Video Library, capture and playback to and from video destinations
digital movie recording, editing, and playback
The CL provides three interfaces, for successively more complex compression: a still image API for single images, a sequential access API for video-streaming applications, and a buffered interface. Chapter 2, “Programming With the Compression Library,” explains these interfaces in detail.
The CL works with other Silicon Graphics Digital Media libraries—Audio Library (AL) and Movie Library (ML)—as well as the Video Library (VL).
| Note: Although the CL supports audio compression, the Indigo2 IMPACT Compression board does not. |
The Video Library provides a software interface to the Indigo2 IMPACT Compression board, which lets applications
capture live video in system memory
encode graphics to video in real time
produce full-rate video output
The Video Library (VL) is a collection of device-independent and device-dependent C language calls for Silicon Graphics workstations equipped with video options. The VL provides generic video tools, including simple tools for importing and exporting digital data to and from Silicon Graphics systems or third-party video devices that adhere to the Silicon Graphics architectural model for video devices.
Chapter 3, “Programming With the Video Library,” explains the basics of using the VL to create video programs for Indigo2 IMPACT Compression.
| Note: See page 10 for information on the order of operation between CL and VL calls. |