Cinepak

Developed by Peter Barrett at SuperMac Technologies.

General Information

Cinepak is the most widely used cross-platform, software-only, scaleable codec (compressor-decompressor) for creating video for distribution on CD-ROM, game titles, and over the Internet.

Cinepak compressed video can be played back on any licensed platform. QuickTime is required for playback on Apple Macintosh and MacOS compatible systems. For playback on a Windows OS platform, either Video for Windows or QuickTime for Windows is required. No additional hardware is required for playback. Cinepak compressed video can be decompressed on machines as "lightweight" as an LC III, or a 20Mhz 386.

Cinepak uses a vector quantization algorithm, which allows it to play back at higher frame rates on most systems. As a software-only codec, it requires no special hardware for compression or playback. The Cinepak codec allows generation of bit stream with a stable and predictable data rate. This facilitates distribution of compressed video on CD-ROM and on the Internet. On playback, the Cinepak codec uses very little processor bandwidth, leaving plenty of processor power available for other tasks. This is of significant benefit to developers of interactive content.

Making Better Cinepak Movies

Cinepak movies can be played on a variety of computing and gaming platforms. licensees include Apple computer, Microsoft Corporation, Atari Corporation, Sega of America, Time Warner Interactive, Next Computer, Creative Labs, Cirrus Logic, Western Digital and Weitek Corporation.

Radius Telecast, VideoVision Studio, SpigotPower AV, Spigot II Tape and the original VideoSpigot are all natural production tools for creating Cinepak movies. By following the steps outlined below, Cinepak material can be authored to maintain the high quality this technology provides.

Step #1: Creating the Content

Rule #1: Keep The Video Pristine

Compression is possible because of the spatial and temporal redundancy within video. The biggest issue in maintaining the highest-quality compressed video, independent of the CODEC, is keeping the source material as free from noise as possible. The random nature of noise reduces this redundancy or can inhibit its detection.

CCD elements and vidicon tubes in video cameras generate noise in low light situations. Therefore, well-lighted scenes produce the highest-quality footage. Three chip/tube cameras produce the best results but more light is usually a better compromise if a choice must be made between the two.

Rule #2: Use High Quality Media

The quality of the recording media should be carefully chosen. Hi-8, S-VHS or better should be used for capture. Betacam SP and above are preferred media as the recording noise levels can be kept at near inconsequential levels. 8mm and Hi-8 tapes wear out rapidly, causing "Drop-Outs". Play these tapes as few times as possible before digitizing. When possible, dub the original tapes, and do as much preliminary work as possible using the copies.

Remember, noise reduction starts with production planning and ends with the final encoding of the video stream.

Step #2: Adjust Input for Proper Video Levels

The Cinepak compressor performs best when using signals that contain an even distribution of luminance and chrominance levels. Adjusting the Image controls (in Adobe Premiere™, under the Movie Capture -> Video Input -> Image menu) to optimum levels for your content can improve this distribution, resulting in a higher quality Cinepak encoded movie.

For the perfectionist, distribution can be checked by capturing a single frame from your source, loading it into Adobe Photoshop and performing a histogram. Adjusting the input parameters of the Digital Video capture board for a wider distribution and iterating this process can yield improved image quality.

Step #3: Use the Highest Quality for capturing

At higher compression ratios, JPEG can introduce artifacts that add correlated noise to the video stream upon decompression. This noise not only reduces the quality of the video but makes it more difficult to compress as well. Increasing the quality of the JPEG capture reduces these artifacts. Using fast drives or arrays, and a fast SCSI-II controller (SCSI-II NuBus controllers not recommended with SpigotPower AV or Spigot Pro AV), enables capture at the highest rates.

If cost or availability prohibits the use of faster larger hard drives, some capture boards allow you to reduce the capture rate from 30 fps to the target rate of the Cinepak movie. Since capturing at 640 x 480 allows a higher-quality resize in the preprocessing (as explained below), it is preferred to reduce the frame rate before you consider reducing the capture size.

Step #4: Edit your video, add transitions and titles

Here's where you get to be creative. Using the editing package of your choice, place your captured clips in sequence, add titles and transitional effects and add or adjust the sound as necessary to create your video masterpiece. When you've got it just right, save your project as a QuickTime movie.

Step #5: Resize and Filter With Adobe "AfterEffects"

Once a video has been captured and edited, AfterEffects can be used to maintain the quality of the source during resizing operations. Additionally, AfterEffects offers some preprocessing of the video that will improve the quality of the Cinepak compressor.

If the target size of the Cinepak video is to be smaller than the capture size, AfterEffects should be used for the resizing. AfterEffects resizes using a bi-cubic spline that maintains the linearity of the video images. Adobe Premiere 4.0 uses a nearest-neighbor method that introduces aliasing artifacts, reducing the quality of your video. Capturing at 640 x 480 and resizing to 320x240 or smaller sizes with AfterEffects prevents these artifacts.

The method for processing the video is simple. First, in AfterEffects, open your video source file (File -> Open). Create a new Composition (Composition -> New). Select the video source in the project window and drag its window into the composition window. In the properties window, select "scale" and resize to the target size. This is also a convienient way to eliminate noise along the edges of your video. Resizing to 102% (or more) may be just enough to move head noise out of the visual range.

Residual noise and JPEG-transition ringing adversely affect the Cinepak compression quality. Some video clips may benefit from the application of a Gaussian Blur filter, which smoothes out JPEG ringing and reduces noise without adversely affecting the video. Select the Gaussian Blur filter (Effect -> Gaussian Blur) and slide the control to "0.4." You can experiment with this value, but it usually doesn't take much. Finally, make your movie (Composition -> Make Movie). Click "OK" and wait for the process to complete.

Step #6: Crop, Set Data Rate, and Convert to Cinepak

Use MovieShop to perform final cropping (to eliminate noise in overscan areas, etc.) Set up final Frames per Second (FPS) resampling if needed, and set Data Rate constraint. We suggest 100Kb/sec for single speed CD/ROMs, and 180-210Kb/sec for double speed drives.

See Also

• Radius

Small Computer System Interface