While this problem may be caused by any number of Windows devices, such as the video
acceleration mentioned in a
previous post, the problem is often caused poor memory management by Windows. Due to
the behemoth size of
Windows, many parts of memory get moved from RAM to the swap file at inopportune
moments. When parts of the sound
program or drivers get pushed out inappropriately, the result is clicks, stutters, and
buzzing. Sometimes the code that
redraws the mouse cursor gets swapped, causing jerky mouse movement. The Real Audio
folks suggest a program called
"Free Mem Pro", which exploits this inappropriate swap behavior in a way that actually
improves the situation. Disabling
swap is not for the faint of heart, and requires at least 256 MB RAM.
Another problem that sometime occurs is that certain players (like Windows Media
Player) do crude audio/video
synchronization by duplicating/deleting samples in an attempt to maintain sync. WMP
does this even when playing audio
only, when there is really no need to do it. This algorithm is *much* cruder than the
MDs sampling rate conversion
algorithm. The WMP algorithm tends to add a slight "gurgling" sound. My guess is
that the severity depends on how far
apart the various clock signals in the computer are. For maximum quality, use a
playback program like Cool Edit, that does
not use the multimedia synchronization stuff.
The sound output may be going through Windows software sample rate convertor, which is
comparitively low quality and
often introduces artifacts, such as clicks. A program like Cool Edit has its own
sample rate convertor that can be adjusted
to a much higher quality. But unless you've got a really fast CPU, Cool Edit's high
quality algorithm can not hope to keep up
with real time. MP3 decoding and sample rate conversion must be done as separate
tasks before playback begins.
On the topic of WMP (if you must use it), it is best to minimize it to the taskbar
while playing so it doesn't have to draw the
screen "visualization". On my 466 Celeron, WMP takes about 6% CPU utilization to play
an MP3 minimized. It takes
almost 60% CPU utilization to play MP3 and draw the screen visualization!
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