[mythtv-users] Commercial Detection during recording

[Brian J. Murrell]

On 13-03-11 11:28 AM, Robert Dege wrote:
> Does enabling "Auto-commercial-detection jobs when recording starts" add a
> significant amount of overhead to the system?  Right now, I can
> simultaneously record three shows (via HD Prime) onto two physical hard
> drives, while I'm watching a previously recorded show without issue.  I'm
> just wondering if the additional commercial detection (3 max) would be too
> much for the system.

Too much of what?  Additional disk I/O or CPU to do the decoding and
detection?

Ideally, your commercial detection processes can keep up with the
writing of the recording to the disk (i.e. real-time) because then you
shouldn't incur additional disk I/O (i.e. to read the stream to be
flagged) on your storage disks since the disk blocks the commflagger
will be wanting to read will already be in the page cache as they got
read from your tuner and written to the storage disk.  Assuming your
page cache is big enough (i.e. you have lots of memory left over after
all of your processes grab what they want).

So, the upshot is that there could be no additional disk I/O but of
course there is additional CPU usage and there needs to be enough CPU
available in order to avoid the additional disk I/O.

Cheers,
b.



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