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Compression Settings: QuickTime

Use the Compression Settings dialog to choose a codec and its related settings for a QuickTime movie. The default codec is Animation.

Note: If you click Process to begin rendering before setting these options, combustion will prompt you to do so before continuing.

Several compressors are built into QuickTime, and each has its advantages and disadvantages.

To set the QuickTime compression settings:
  1. On the Output Settings panel, select QuickTime from the Format list.
  2. Click Options.
  3. The Compression Settings dialog appears.

  4. Select a codec from the Compressor list. For information on the options available, see Choosing a QuickTime Compressor.
  5. Select a bit depth (the number of colors to be used in the file) from the Compressor color list. The available color resolutions depend on the codec selected.
  6. One of the choices is Best Depth. Best Depth reads the highest bit depth from your system and uses that for the codec. It shows up in all QuickTime codecs.
  7. Note: Larger bit depths provide richer results, but take more space to store. Smaller bit depths take less storage but may not reproduce the images adequately, or may cause "stepping" or "banding". In most cases, you should set the bit depth to Millions of Colors, or higher.

  8. Adjust the following options, as required.

    Use:
    To:

    Quality

    Set the Spatial Quality (compression of each frame's pixel data).

    Frames Per Second

    Enter the frame rate of the final QuickTime movie. This setting will override the frame rate setting of the composite.

    Key Frame Every

    Add a complete frame at the specified interval. Most codecs add keyframes when necessary, usually when the difference between frames is greater than 90%.

    Limit Data Rate To

    Create a movie that "maxes out" at the specified data rate per frame. Use this option (if the selected codec supports it) to create movies optimized for CD-ROM or web playback.



  9. Note: When choosing a frame rate, you should note that the human eye requires at least 12 frames per second to be "tricked" into seeing motion. With anything below this, the motion may not be smooth.

  10. Click OK.

Choosing a QuickTime Compressor

The following options are typically available when standard Apple® QuickTime software is present. However, they may vary depending on your installation. You must select both the compressor type and the number of colors present in the QuickTime file.

To output a file containing an alpha channel along with color information, select either Animation or None from the Compressor list and Millions of Colors+ from the Compressor color list.

Note: Not all compressors can handle all color resolutions.

Animation

Uses run-length encoding to compress frames of the movie. This compressor uses a lossless method when the Quality slider is set to 100%, and a lossy method otherwise. This codec supports all color depth resolutions, including alpha channels.

Cinepak

Uses a compression algorithm that allows for fast decompression at the expense of relatively slow compression. It is well suited for playback on the computer via a CD-ROM or other media. Cinepak is a lossy method regardless of the quality setting. However, you can usually get real-time playback with a wide variety of processor speeds using this codec. Alpha channels are not supported.

Component Video

Uses a compression algorithm optimized for YUV color space. This method can be slow in both compressing and decompressing a movie, and as such, is usually used for archiving or storing video footage only. Alpha channels are not supported.

DV NTSC and DV PAL

DV NTSC and DV PAL are designed for video created with today's inexpensive yet high-quality digital camcorders. The compression and data rate are fixed at 3.6 MB per second.

Graphics

Uses a similar compression algorithm to Animation, but only supports up to 8-bit color or grayscale (256 shades of color/gray). This codec typically compresses better than Animation (smaller file size), but takes more time to decompress the data than QuickTime. Alpha channels are not supported.

H.261

H.261 is a standard video-conferencing codec. It is designed for low data rates and relatively low motion. H.261 was used as a starting point for the development of MPEG (which is optimized for higher data rates).

H.263

H.263 is a standard video-conferencing codec. It is optimized for low data rates and relatively low motion. H.263 is an advancement of the H.261 and MPEG-1 standards, designed with the goal of producing substantially better quality below 64 Kbps. There is a wide range of architectures that support H.263.

Motion JPEG A and Motion JPEG B

Are designed to simplify the process of digitizing video on one QuickTime-compatible video card and playing it back on another. These codecs are essentially "generic" versions of the Motion JPEG codecs that many manufacturers use in a proprietary way.

You can use these codecs to generate QuickTime movies that can be played back on any Motion JPEG-based video cards or systems that support this feature of QuickTime (Avid®, Media 100®, and TARGA, for example). These codecs do not support alpha channels.

None

Uses no compression on the QuickTime movie. This codec would typically be used for storage of a movie that needs to be identical to the original. However, you can use the Animation compressor at 100% quality to save hard drive space since None can generate very large files. This codec supports all color depth resolutions, including alpha channels.

Photo - JPEG

Uses the Joint Photographic Experts Group compression algorithm. This codec works well with digitized imagery, but not as well for computer-generated imagery. Decompression for playback can be very slow, so this codec is also best used for storage purposes. Alpha channels are not supported.

Sorenson®

Uses new vector quantization techniques, advanced motion compensation, and precise adaptive rate control features. It provides highly compressed, high-quality video stream for use in multimedia applications, the World-Wide-Web, or any other application where a high-quality, low-bandwidth video stream is required. The compression technology is scalable from 2 to 200 Kbps, providing great results whether publishing to a 28.8 Kbps modem or to a CD-ROM. It allows for a video data transmission rate of up to 30 frames per second. This codec does not support alpha channels.

Video

Uses a compression algorithm optimized for fast decompression. However, this codec supports up to 16-bit color depth only, so it may not be suitable for most projects created with combustion. Alpha channels are not supported.

Note: These are not the only codecs you might encounter; if you installed a QuickTime-compatible video card or additional QuickTime software, there may be additional codecs available to you. For more information about these, consult the manual of your particular video card or software.


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