{"id":1466,"date":"2013-07-20T16:25:06","date_gmt":"2013-07-20T14:25:06","guid":{"rendered":"https:\/\/alax.info\/blog\/?p=1466"},"modified":"2014-02-09T18:54:52","modified_gmt":"2014-02-09T16:54:52","slug":"breaking-windows-update-of-windows-media-video-9-decoder","status":"publish","type":"post","link":"https:\/\/alax.info\/blog\/1466","title":{"rendered":"Breaking Windows Update of Windows Media Video 9 Decoder"},"content":{"rendered":"

One of the recent updates delivered via automatic Windows Update is breaking video decoding for Windows Media Video streams (four character code WMV3<\/code>). It’s hard to trace things back, however the most likely issue is the update of WMVDECOD.DLL<\/code> file which is dated 6 May 2013 delivered with MS13-057: Description of the security update for Windows Media Format Runtime 9 and 9.5 (wmvdmod.dll), and for Windows Media Player 11 and 12: July 9, 2013<\/a>, and it could be one or more versions before as well. The breaking update also affects Windows XP systems.<\/p>\n

The problem is affecting both Win32 and x64 systems, and Windows XP and later, however it might be affecting them differently. While in Windows 7 the top half of the video is damaged, in Windows XP the output is totally black. There might be other factors affecting the output though.<\/p>\n

\"Broken<\/a><\/p>\n

The problem is only taking place when WM Video decoder is set to decode into 32-bit RGB format. This limits the impact to application forcing output to RGB for grabbing purposes, or use post processing in RGB domain. Decoding into YUV and 24-bit RGB formats looks correct.<\/p>\n

The problem is easy to repeat and it is only necessary to force the feed to decode into 32-bit RGB, for instance using Sample Grabber Filter<\/a>:<\/p>\n

\"Filter<\/a><\/p>\n

The workaround is not to avoid decoding into 32-bit RGB. In particular, in Windows Vista one can decode into something else and then convert to 32-bit RGB using Color Converter DSP<\/a>.<\/p>\n

Links<\/h3>\n