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Low Resolutions: Better With Slow Motion Codec!

MPEG-4: Optimization of Picture Quality and Data Rate
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The same sequence prepared with the slow motion codec. Artefacts occur especially in the transitions of individual people.

Our test clearly establishes that if video sequences are prepared up to a resolution of 352 x 288 pixels (half PAL resolution), then the slow motion codec is definitely better suited! In this range, the video quality of the slow motion codec is better in spite of a lower data rate than with the fast motion codec with a higher data rate. The situation is completely different if the resolution exceeds 352 x 288 pixels. In this case, the fast motion codec should be used, irrespective of the film content (fast or slow movement). By way of a test sequence, we used the DVD video "The Jackal", which was coded up to 720 x 576 pixels with different resolutions. Especially with a full PAL resolution it was shown that the fast motion codec produces very good video pictures with a relatively low average data rate.

Video Resolution MPEG-4-Codec, Data Rate Overall Data Rate Quality Length of Film on CD-R
720 x 416 Pixels Fast-Motion, max. 6000 kBit/s 145 kB/s very good 83 min
720 x 416 Pixels Fast-Motion, max. 900 kBit/s 128 kB/s good 94 min
720 x 416 Pixels Slow-Motion, max. 6000 kBit/s 216 kB/s very good 55 min
720 x 416 Pixels Slow-Motion, max. 900 kBit/s 128 kB/s satisfactory 94 min

This table compares the two MPEG-4 codecs with a full PAL resolution. The slow motion codec produces a higher data rate with high resolutions than the fast motion codec.

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