[mythtv-users] Automation query

[Michael T. Dean]

On 02/12/2011 06:17 PM, Yeechang Lee wrote:
> If 0.24 has functionality that prevents the issue from occurring I am
> glad to hear it as I am still on 0.23. What does setting the timeout
> to 10 seconds do? Is it a delay between channel changing and
> attempting to lock on the signal? If so I imagine it would make using
> live TV painful.

For the first time, ever, MythTV 0.24+ monitors external channel change 
progress so that it can determine when to begin recording, even for 
long-running channel-change scripts.  With earlier versions of MythTV, 
if you had a channel change script that could run for more than a second 
or 2, you'd have to background the script--so mythbackend starts 
recording immediately, even before channel change was complete--and hope 
that everything worked out.

The HD-PVR, though, is very temperamental and if you began recording 
before it had gotten a "lock," it would cause problems.  Therefore, John 
Poet wrote code to monitor the channel change script and start recording 
once it completes.

If you set the timeout to 10s and your external channel change script 
takes 0.00005 seconds to complete, mythbackend will start recording 
after 0.00005s (well, plus a few ms or whatever it takes since nothing 
is instantaneous :).  If your channel change script takes 9s, though--as 
can happen for an HD-PVR to become ready to record under some 
circumstances--mythbackend will wait until the device is ready before 
beginning to record.  In other words, nothing changes as far as the 
performance of the HD-PVR or channel changes with the HD-PVR, but rather 
than have a built-in "wait a few seconds just in case", we can start 
recording as soon as the device/drivers are ready (which will, in 
general, likely be around the same wait time as with the previous 
hard-coded wait, but could be shorter or longer in some circumstances).

The reason I mentioned the timeout is because since that timeout value 
was never used before for capture using inputs that required external 
channel change scripts, users who upgrade their databases from previous 
versions may have invalid/incorrect values for the timeout for their 
devices/channel change scripts.  Therefore, anyone who uses an external 
channel change script and upgrades to 0.24 should verify the values are 
sensible.

That said, if you upgrade to 0.24-fixes from this Thursday or later, you 
will almost definitely see /much/ faster and more reliable Live TV and 
playback startup, and possibly faster channel changes in Live TV, thanks 
to some great work done by Mark Kendall and Taylor Ralph.  I highly 
recommend the upgrade--especially for Live TV users.

Note, though, you need a /very/ new 0.24-fixes.

Mike