[mythtv-users] commflag on master very unreliable any more

[Robert McNamara]

On Wed, Jan 25, 2012 at 10:50 AM, Tim Draper <veehexx at gmail.com> wrote:

> On 25 January 2012 15:04, Tim Draper <veehexx at gmail.com> wrote:
> > On 25 January 2012 14:09, Brian J. Murrell <brian at interlinx.bc.ca>
> wrote:
> >> On 12-01-25 09:02 AM, Tim Draper wrote:
> >>>
> >>> google sugests that UK signals do not abide by the same comskip rules
> >>> as other countries - blank frames not present for example,
> >>
> >> Have you examined a recording to verify this?  You can start a recording
> >> on a FE and then hit 'e' which puts you into editing mode.  From there
> >> you can use the left/right arrows to step through the recording at
> >> predefined intervals (i.e. 1 frame, 0.5 seconds, 5 seconds, ... 5
> >> minutes, etc.) and use the up/down arrows to adjust the size of the
> >> interval.
> >>
> >> I typically start scanning through with a 1 minute interval and when I
> >> find myself in a commercial I just keep going back and forth over the
> >> start of the commercial break with smaller and smaller intervals until I
> >> can go into and (reverse back out of) the commercial break a frame at a
> >> time.  That lets you see what exactly is between the show and the start
> >> of the commercial break.
> >>
> >> If you are seeing blank (black) frames, commskip should would for you
> >> too.  If it's not, perhaps you are having the same problem as I.
> >>
> just tried this - i'm seeing 13 frames that are completely black where
> detection should start.
> 6 black frames where detection should end.
>
> also, the channel has a logo in the top left corner too, which i
> believe is a valid method to check for commercials.
>
> reality is that this recording has 0 commercial detections in it.
>
>
> not wanting to hi-jack the thread, should i post a new message to the
> ML? the OP is running 0.25 master, i'm running mythbuntu 0.24.1, or is
> commercial detection the same between these releases?
>


Simply finding black frames is not an indication that commflagging should
find a break there.  There is a LOT more going on that simply finding black
frames.  commflagging is known not to work well in many locales,
particularly in the UK and Australia.  This is not a bug, it's just a
limitation of the current commercial flagging capabilities.  Patches are,
as ever, cheerfully accepted when if you have one which improves things for
other locales whiles not compromising existing performance.

The OP has mentioned an inability to seek ("already at end") in the files,
which is likely the real root cause of the issue-- the commflagging is
probably fine, but if the player doesn't know where it's at in the stream,
it can't skip to the correct cutpoints.  In almost every case, this is the
result of database issues, most often broken individual seektables, but it
could also be another crashed table or other issue.  Seeing the (partial)
contents of recordedseek for the recording in question would likely be
interesting.  It's entirely possible that the incoming stream is in some
way broken, but whether or not supporting a broken stream is a bug or a
feature request is a grey area, with my personal feelings being that if it
involves too much of a workaround, it's not ok.

Robert
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