Mac Forum / General / Portable Macs / July 2006

The error message faults the HD. Have you tried recording it to an
external HD of some sort to see if the behavior is any different?

There are also other programs that can record audio, which might have
lower requirements than iMovie (e.g. wiretap pro, audio hijack). Audio
Hijack has a free demo as well.

Disks in laptops tend to be slower.  I don't know if they're slow enough
to matter with audio, though.

I expect the issue is playing video and recording audio at the same time
on the same hard drive. I expect the drive is fast enough for either
task separately.

For a sigificant amount of data being transferred, this may result in
the head seeking back and forth between the video file being read and
the audio file being written. This seeking will introduce delays in the
playback and/or recording. Playback delays can be dealt with by skipping
ahead in the data (dropping video frames), but recording must be
uninterrupted.

iMovie will have a memory buffer for capturing the audio commentary
track, but if the drive isn't keeping up with the recording then the
buffer will fill up, resulting in the error message you have seen.

Moving the video or audio to a different hard drive would be the best
solution, as this will eliminate most of the head seeking delays.

Another possible explanation might be lack of memory: if your computer
is having to rely on virtual memory to run QuickTime Player and iMovie
at the same time, then you might have a major performance hit due to
memory being swapped in and out between the two applications.