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MPEG-4: Optimization of Picture Quality and Data Rate

Compromise: Quality Vs. Resolution

ResolutionBitrate Video MPEG-4Data Rate AudioOverallQualityLength of Film CD-R 74Length of Film CD-R 80Length of Film CD-R 99
VideoFast-Motion-CodecFraunhofer CodecData RateBurn to CD-RBurn to CD-RBurn to CD-R
176 x 112 Pixelsadaptive, max. 6000 kBit/s128 kBit/s, 44 KHz, Stereo37 kB/svery good300 min323 min370 min
240 x 192 Pixelsadaptive, max. 6000 kBit/s128 kBit/s, 44 KHz, Stereo45 kB/svery good247 min266 min303 min
352 x 224 Pixelsadaptive, max. 6000 kBit/s128 kBit/s, 44 KHz, Stereo70 kB/svery good159 min171 min195 min
480 x 288 Pixelsadaptive, max. 6000 kBit/s128 kBit/s, 44 KHz, Stereo94 kB/svery good118 min127 min145 min
576 x 336 Pixelsadaptive, max. 6000 kBit/s128 kBit/s, 44 KHz, Stereo109 kB/svery good102 min110 min125 min
640 x 480 Pixelsadaptive, max. 6000 kBit/s128 kBit/s, 44 KHz, Stereo129 kB/svery good86 min93 min106 min
720 x 416 Pixelsadaptive, max. 6000 kBit/s128 kBit/s, 44 KHz, Stereo145 kB/svery good77 min83 min94 min

This table shows the increase in the data rate depending on the chosen codec and the respective resolution. Furthermore, instructions are given for writing a DVD video onto a CD-ROM depending on the respective CD-R.

Especially in the case of DVD videos that have a playing time of more than 90 minutes, it is often the case that the storage capacity of a CD-ROM with just under 700 MB (CD-R80) is not sufficient. In order to avoid having to split the DVD video onto two CD-ROMs the average data rate should be reduced when carrying out the MPEG-4 encoding. In principle, there are two different ways of doing this. On the one hand, the resolution can be slightly reduced or, on the other hand, you have to marginally sacrifice picture quality, so that the data rate is lowered with a consistent resolution.

The following screenshots taken from our test sequences show the extent to which the different resolutions affect the average data rates.

All three video sequences were prepared with the slow motion codec and different bit rates. While the lowest resolution only requires 250 kBit/s, the resolution with 352 x 224 pixels needs as much as 700 kBit/s.