<P> Multimedia Class Scheduler Service (MMCSS) is a Windows service that allows multimedia applications to get prioritized access to CPU for time - sensitive processing (such as multimedia applications) as well as prioritized disc access to ensure that the process is not starved of data to process . The MMCSS service monitors the CPU load and dynamically adjusts priority so that the application can use as much CPU time as possible without denying CPU to lower priority applications . MMCSS uses heuristics to determine the relative priority required for the task the thread is performing and dynamically adjusts priority based on that . A thread must invoke MMCSS explicitly to use its services by calling the AvSetMmMaxThreadCharacteristics () or AvSetMmThreadCharacteristics () APIs . </P> <P> MMCSS is used by the multimedia applications in Windows Vista, including Windows Media Player and Windows Media Center to provide glitch - free audio playback . </P> <P> This service has been implicated in poor networking performance while multimedia is playing., In response to this, Microsoft has included a configurable option in Windows Vista Service Pack 1 and later where users can specify the network throttling index value for the Multimedia Class Scheduling Service so that network performance and audio / video playback quality can be balanced according to how users configure it . </P>

Multimedia class scheduler service entered the running state