The what's new file list's the following improvements/bugfixes for 5.01:

Improved:

• Psychovisual modeling enhancements now reallocate saved bits in an improved manner, meaning the psychovisual modeling mode will produce better visual quality.
• Improved the workaround for a DirectShow bug that causes the requested bitrate to not be respected by the codec during one-pass encoding. This affects applications (such as video capture applications) that use the DivX DirectShow interface to access the codec. This problem is due to a bug in DirectShow, not in DivX itself, but we have a workaround that should solve the problem.

Fixed:

• Fixed a bug where the divx.dll library would not decode DivX 3.x content properly. This affected applications like VirtualDub that use the VfW interface to use DivX. The problems this caused, such as blank frames, are now fixed.
• Fixed a bug where basic deinterlace functionality would cause the codec to crash on Pentium 4 processors.
• Fixed a problem where using data paritioning and psychovisual modeling together would produce severe visual artifacts. These settings can now be used together.
• Fixed an issue where encoding content with resolutions not divisible by 16 would cause purple and pink artifacts to appear in the encoded content. These artifacts no longer appear. You can now encode content that has resolutions divisible by 4 or 8, however we still strongly recommend encoding only content with resolutions divisible by 16, as the 4 and 8 dimensions will not encode as efficiently. (There remains a known issue about resolutions divisible by 2.)
• Fixed a bug where the DirectShow filter would not use the overlay properly with Matrox Millennium video cards on Windows 2000. It now works properly.