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Digital Video (DV) Codec Optimizations

QuickTime 5 includes the following:

• Digital video (DV) codec optimizations that are designed to provide significant performance and quality improvements over previous versions.

• Support for optimized high-quality decompression on Power Mac G3 and G4 computers. This support is designed:

  • to improve speed for rendering in r408 and v408 formats.

  • to improve speed for playback to YUV accelerated windows.

  • to improve speed for high-quality, single field video.

• Improved quality compression in medium and best-quality cases for Power Mac G3 and Power Mac G4 computers.

• Improved quality of normal (low) quality decompression on Power Mac G4 computers.

These enhancements are aimed at developers and content authors using tools such as video editing applications.

In this section:

High-Quality Decompression
Improved Compression Quality and Performance
Improved Low-Quality Vector Decode
Addition of Multiprocessor Support

High-Quality Decompression

Both scalar and vector codec quality has been improved significantly in this release. There are performance improvements as well. The code is optimized in both scalar and vector codecs to pack pixels directly to the output format, which provides a significant improvement in performance for r408.

QuickTime 5 supports optimized single field decompression, which improves performance for cases when the single field hint (hintsSingleField) is set. The vector codec now includes gamma correction when decompressing to the screen.

Improved Compression Quality and Performance

Overall, there is a significant improvement in both compression quality and performance. Special attention has been paid to make sure that existing DV content can be recompressed with few additional artifacts.

Improved Low-Quality Vector Decode

The quality of low-quality decode on vector machines (400 MHz or greater) has been improved, while also improving performance.

Addition of Multiprocessor Support

Multiprocessor support has been enabled for vector decode (i.e., high quality, low quality, playback and scrub/render). Multiprocessor support has also been enabled for encode in the vector case. For the actual DV operation, the results are nearly two times faster on a two CPU computer than the same code running in non-multiprocessor mode.

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