On 10/08/2012 17:45, DaveC wrote:
When I take a video with my Canon PS G9 it will automatically stop recording
anywhere from 20 minutes to 1 hour. Why such a variance?

It depends strongly on the compressibility of the material in the MPEG
stream (or whatever method that camera used). An active scene with
people moving panning and/or zoom will require a lot more storage space
that a picture of a still life arrangement of fruit on a table.

Battery is not the issue: I can start another video and likewise it will
record for a similar time.

The manual says that 4 GB is the max video file size it will record (indeed,
the files are all 4 GB), but that the max time will vary. The manual says:

"Even if the clip size has not reached 4 GB, recording will stop at the
moment the clip length reaches 1 hour. Depending on memory card capacity and
data write speed, recording may stop before the file size reaches 4 GB or the
recording time reaches 1 hour."

The 4GB is a hardware limitation of the file system typically used on
removable media. Even proper video cameras often split long files every
4GB to deal with this limitation. The 1 hour timeout is artificial and
imposed by the manufacturer fairly gratuitously.

I have to say that my Inxus 100IS burns through its battery when taking
video and becomes quite hot after about 5 minutes.

My question is: what variables cause the max time to vary? If I'm using the
same memory card (SDHC, Samsung 32 GB, class 10), why not identical video
times?

(These tests are done with identical settings: when a video has stopped
recording I just push the shutter button again.)

Thanks.

If you film a static scene with MPEG encoding it will be rather easily
compressible.

Regards,
Martin Brown