Technical Q&As
QTW 64 - Intermittent Pixellation with CinePak Compression (1-Aug-95)
Q We are getting good results compressing with CinePak at around 230K/second.
Based on the recommended data rates (180-200K/second), we started compressing
to 150K/second for video (320x240x15fps). Occasionally, we see a strange sort
of pixellation during certain scenes. While these artifacts soon disappear,
they look very bad. We have seen this on various computers using MovieShop,
Premiere, and ConvertToMovie. What could be causing this?
A The pixellation is probably due to image content. There are four possible
solutions, which you can try (alone or in any combination):
1. Use a different compression codec, such as Indeo.
2. Lower the frame rate and raise the quality in those portions of the movie
that exhibit the pixellation.
3. To touch-up frames that have noisy (high-frequency) backgrounds, use
PhotoShop.
4. If the problem occurs when dithering on 8-bit color systems, use
DeBabelizer to create an optimized color lookup table (clut).
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