WMS: NSUM.exe Stops Responding When Streaming an .asf File (247947)

SYMPTOMS

NSUM.exe (the Windows Media Services Unicast Manager) stops responding and Windows displays a "division by 0" error when a Windows Media Player client tries to stream a Windows Media video file in which the video bitrate is many times greater than the audio bitrate.

This is the specific error message that appears:

The media file you attempted to play is either corrupted or of an invalid file type. Refer to Windows Media Player Help for a list valid media file types. (Error=C00D002F)
Cannot open 'http://myserver/8mbps.asf'. (Error=800704C9)

CAUSE

When media is encoded with the audio portion at a low bit rate and the video portion at a high bit rate, the resulting .wmv file contains packets with audio data that is less than one millisecond. For example, if the video portion is encoded at 8 Mbps and the audio portion is encoded at 8 Kbps, this sort of error can be expected. At those rates the video rate is 1,000 times the bitrate of the audio. Optimally, the video bitrate should be in the range of 1 to 15 times the bitrate of audio.

RESOLUTION

This behavior is by design. Packet sizes that are radically different from what is considered optimal should be avoided.

WORKAROUND

When encoding audio streams, you should match the encoded bit rate with the expected stream bit rate.